geosciences

Review Bradoriids (Arthropoda) and the Cambrian Diversification

Mark A. S. McMenamin

Department of Geology and Geography, Mount Holyoke College, South Hadley, MA 01075, USA; [email protected]; Tel.: +413-538-2280



Received: 2 March 2020; Accepted: 25 March 2020; Published: 27 March 2020


Abstract: Bradoriids, among the earliest arthropods to appear in the fossil record, are extinct, ostracod-like bivalved forms that ranged from the early Cambrian to the Middle Ordovician. Bradoriids are notable for having appeared in the Cambrian fossil record before the earliest trilobites, and considering their rapid ascent to high genus-level diversity,provide key data for our understanding of the evolutionary dynamics of the Cambrian Explosion. This paper presents a broad review of bradoriid paleobiology. It is hypothesized here that an allele of Antennapedia determines whether bradoriid shields are preplete, amplete, or postplete. The preplete configuration of the shields of Cambroarchilocus tigris gen. nov. sp. nov. suggests that shield rowing motion may have propelled the animal backwards. Arcuate scars attributed here to a microdurophagous predator (Arcuoichnus pierci nov. ichnogen. nov. ichnosp.) occur on the paratype of Cambroarchilocus tigris gen. nov. sp. nov.

Keywords: Arthropoda; Bradoriida; Cambrian; Chengjiang; Sonora; México; Antennapedia complex; durophagous predation; ichnofossils

1. Introduction Bradoriids (Bradoriida Raymond, 1935 [1]) are small bivalved basal euarthropods that appeared in shallow marine habitats during Cambrian Stage 3. The largest known bradoriid, Petrianna, is 17 mm long [2]. Bradoriids show a variety of modes of preservation (phosphatization being the most common [3–8]), and are particularly abundant in the Chengjiang Lagerstätte. Bradoriids such as Sinskolutella and Yakutingella are thought to have been detritophagous feeders [8] or possibly meiofaunal micropredators [5]. Bradoriids enter the fossil record before the first trilobites (shortly before the appearance of trilobites of the Abadiella Biozone) [3–5], and as such provide important data regarding the dynamics of the Cambrian Explosion. They are among the earliest arthropods recognizable in the fossil record [6]. Plausible inferences suggest that bradoriids may have an even earlier (pre-Atdabanian or Cambrian Stage 2) history [6], with Williams and coauthors [5] assuming that bradoriids had undergone significant evolution before their near simultaneous appearance in different parts of the world. This pattern of early appearance and rapid diversification in bradoriids has been remarked on since Raymond C. Moore’s 1961 diagram entitled “Stratigraphic distribution of archaeocopid ostracodes (sic)” [7], which shows 75% of the dozen listed genera as appearing at the base of the Cambrian. Paleontological interest has been building for the group, showing an accelerating increase in described genera in recent decades (Figure1). The raw data for this graph are the description dates in the section of this article on bradoriid genera, as seen below.

Geosciences 2020, 10, 119; doi:10.3390/geosciences10040119 www.mdpi.com/journal/geosciences Geosciences 2020, 10, x FOR PEER 2 of 37

Geosciences 2020, 10, 119 2 of 37 Geosciences 2020, 10, x FOR PEER 2 of 37 Bradoriid Genera Descriptions 12 Bradoriid Genera Descriptions 12 10

10 8

8 6

6 4 Genus Descriptions 4 2 Genus Descriptions 2 0 1800 1850 1900 1950 2000 2050 0 Year 1800 1850 1900 1950 2000 2050 Year Figure 1. Descriptions of new bradoriid genera by year. Data from “Bradoriid Genera” section below.

FigureFigureThe 1. 1.structureDescriptions Descriptions of the of of newnew data bradoriidbradoriid in Figure genera 1, even by year. year. afte Datar Data accounting from from “Bradoriid “Bradoriid for differences Genera” Genera” section sectionover below.time below. in the way bradoriids are studied, is interesting, showing a distinction between “background” descriptions and “massThe structure descriptions”, of the data the latterin Figure reflecting 11,, eveneven primarily afterafter accountingaccounting the publication forfor didifferencesfferences of major over monographic time in the way studies. bradoriidsMass descriptions are studied, haveis interesting, generate dshowing increasing a distinction peaks in between new genus “background” descriptions, descriptions with a recurrence and “mass“massinterval descriptions”,descriptions”, of roughly the 25–35 latter years. reflectingreflecting Background primarily descri the ptions publication remained of majorsteady monographic for a century studies. studies.then began Massto descriptionsclimb steadily have beginning generate generated ind the increasing 1960s. Neither peaks backgroundin new genus nor descriptions, mass descriptions with a appear recurrence to have intervalreached of roughly a plateau, 25–35 suggesting years. Background Background that many moredescri descriptions bradoriidsptions remained remain steady to be discovered. for a century then began to climb Bradoriids steadily beginning show an ininteresting the 1960s. pattern Neither of background diversification nor and mass extinction descriptions that endsappear in to the have Middle reachedOrdovician a plateau, [2]. suggesting Along with that trilobites, many more they bradoriidsbradoriids constitute remainremainpart of totoa bedualbe discovered.discovered. rapid diversification that is an importantBradoriids element show an of interesting the Cambrian pattern Explosion of divers diversification [5].ification A spindle and extinction diagram of that bradoriid ends in diversitythe Middle at the Ordoviciangenus level [2]. [2]. (FigureAlong Along with with2; data trilobites, trilobites, from [2] they they and constitute constitutethe section part part below of of a aon dual bradoriid rapid diversification diversificationgenera) shows that an explosion is an importantof diversity element in Cambrian of the Cambrian Stage 3, Explosionfollowed by [[5].5]. a A Ageneral spindle decline diagram in diversity of bradoriid (with diversity the exception at the of a genuslate level diversification (Figure(Figure2 2;; data data in late from from Stage [ 2[2]] and 5and or the Wuliuan)the section section until below below the on onEarly bradoriid bradoriid Ordovician. genera) genera) shows shows an an explosion explosion of ofdiversity diversity in Cambrianin Cambrian Stage Stage 3, followed3, followed by aby general a general decline decline in diversity in diversity (with (with the exceptionthe exception of a of late a latediversification diversification in late in Stagelate Stage 5 or 5 Wuliuan) or Wuliuan) until until theEarly the Early Ordovician. Ordovician.

Figure 2. Genus-level bradoriid diversity during the Cambrian and Ordovician. Geological dates in million years (Ma). Stages refer to stages of the Cambrian. Numbers to the right indicate diversification waves 1–4. Data from [2] and “Bradoriid Genera” section below.

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Fossil bivalved arthropods in general “provide a powerful tool to investigate the origins and dynamics” of evolutionary diversification [9]. A closer look at the bradoriid diversification in Cambrian Stage 3 reveals some interesting evolutionary dynamics. If we read the bradoriid fossil record literally in Stage 3, we see three waves of diversification during the Cambrian Arthropod Radiation Isotopic Excursion (CARE [2]). Each of these radiation bursts (named here Waves 1–3, with the late Wuliuan radiation as Wave 4) consists of a mix of relatively short-lived genera and long-lived genera (Table1). Short-lived genera are largely confined to a single Cambrian stage, whereas long-lived taxa have ranges that extend significantly beyond a single stage (see Figure 4 in Williams et al. [2]).

Table 1. Bradoriid Radiations. Data from [2].

Short-lived Taxa Long-lived Taxa Wave 1 11 (55%) 9 (45%) (base of Stage 3) Wave 2 16 (76%) 5 (24%) (middle Stage 3) Wave 3 11 (73%) 4 (27%) (late Stage 3) Wave 4 12 (92%) 1 (8%) (late Wuliuan)

These successive episodes of diversification, here called “waves”, are interpreted as actual evolutionary events rather than artifacts of monographic swelling, as stratigraphic control [2] seems sufficient to allow recognition of closely spaced diversification events. An alternate view, namely, that all of these ranges actually extended to the same temporal/stratigraphic horizon [6] remains plausible and should not be dismissed out of hand in spite of the problems (in terms of phylogenetic telescoping, that is, originations of putative ancestor and descendant taxa piling up on the same stratigraphic horizon) that it poses for understanding the Cambrian evolutionary event [10]. The proportion of long-lived taxa originating during successive “waves” shows a general (if not monotonic) decrease from Cambrian Stage 3 to Wuliuan, dropping from an initial 45% to 8%. This is interesting because it would seem to be the inverse to the usual evolutionary expectation, namely, that later diversifications should generate longer-lived taxa, as more time had elapsed to allow improvements to the general “competitiveness” of the taxa involved. To explain the interesting pattern noted in the previous paragraph, one might argue that, with the Cambrian predator revolution [11] underway, it was becoming more difficult for new bradoriid lineages to survive over the long term. This does not explain, however, why Wave 1 generated such a proportionately large number of long-lived taxa. The founder effect may have some explanatory power here; however, a putative founder effect does not explain why some of the very first bradoriid genera remained competitive over the (relative) long term in the face of three additional waves of new taxa. Proffering an explanation based on ‘environmentally-cued polymorphism’ [9] would not explain how Waves 1–3 came to be so closely spaced, seemingly without sufficient time to allow successive rapid diversifications. Bradoriids apparently went extinct sometime during the Ordovician [12]. Some representatives may have persisted until the end-Ordovician extinction, although the latest records are Middle Ordovician and include a Siberian form (with the marvelously alliterative binomial) Chegetella chegitunica [13].

2. Bradoriid Diversification Traditionally and conventionally classified as early ostracods [7], bradoriids lack “specialised post-antennal head appendages and are therefore not Eucrustacea” [2]. The affinities question has been ongoing for some time, with Zittel [14] noting that the Bradoriidae had once been classified as Cambrian Ostracoda but were subsequently removed to other groups such as Branchiopoda [14]. Geosciences 2020, 10, x FOR PEER 4 of 37 been ongoing for some time, with Zittel [14] noting that the Bradoriidae had once been classified as Cambrian Ostracoda but were subsequently removed to other groups such as Branchiopoda [14]. The present-day alternatives are to classify them as stem-group Crustacea [15] or basal/stem euarthropods [16,17]. This revised placement is based on relatively “few strong characters” and it is not certain that bradoriids belong within crown Mandibulata [18]. Edgecombe and Legg note that the “misleadingGeosciences 2020resemblance, 10, 119 of the bivalved carapace to that of ostracods” is also shared 4by of 37other bivalved arthropods from the Cambrian [18]. Phosphatocopids,The present-day a alternativesCambrian aregroup to classifylike bradoriids them as stem-group also once Crustaceareferred to [15 the] or basalOstracoda,/stem are distinguishedeuarthropods from [16 bradoriids,17]. This revisedby “the placement presence isof baseda doublure on relatively on the “fewfree strongmargin” characters” [6]. Exceptions and it isto this may notoccur, certain however, that bradoriids as the Australian belong within bradoriid crown MandibulataZepaera jagoi [shows18]. Edgecombe a clear doublure/duplicature and Legg note that the at the edge“misleading of the shield resemblance [19]. The majority of the bivalved of bradoriids carapace ha tove that postplete of ostracods” or amplete is also shield shared shape, by other although bivalved a few are prepletearthropods (Figure from 3); the preplete Cambrian shape [18]. is more characteristic for phospatocopids [20,21]. Phosphatocopids, a Cambrian group like bradoriids also once referred to the Ostracoda, The list of Cambrian bivalved arthropods is extensive. A partial listing includes bradoriids, are distinguished from bradoriids by “the presence of a doublure on the free margin” [6]. Exceptions to phosphatocopids,this may occur, however,Tuzoia, Branchiocaris as the Australian, Isoxys bradoriid (onceZepaera placed jagoi withshows question a clear in doublure the Bradoriidae/duplicature [14]), Yunnanocarisat the edge, ofOccacaris the shield, Forfexicaris [19]. The majority, Waptia of,bradoriids Clypecaris have, Combinivalvula postplete or amplete, Odaraia shield, shape,Pectocaris, Mengdongella,although a fewand are Jugatocaris preplete (Figure. In fact,3); preplete the bivalved shape is morestate characteristic may be a forplesiomorphic phospatocopids character [ 20,21]. for ArthropodaThe [5]. list ofMany Cambrian of these bivalved groups arthropods were originally is extensive. assigned A partial to Phyllocarida listing includes or bradoriids,Branchiopoda basedphosphatocopids, on valve morphology,Tuzoia, Branchiocaris but these, Isoxys compar(onceisons placed did with not question withstand in the Bradoriidaescrutiny once [14]), limb morphologyYunnanocaris became, Occacaris better, Forfexicaris known ,[18].Waptia The, Clypecaris subseque, Combinivalvulant removal, ofOdaraia some, Pectocaris of these, Mengdongella,groups from the crustaceanand Jugatocaris crown-. Inor fact, even the the bivalved euarthropod state may crown- be a plesiomorphicgroup [18] character recalls previous for Arthropoda proposals [5]. Many regarding of arthropodthese groups polyphyly were originally [22]. Arthropods assigned to are Phyllocarida consider ored Branchiopoda here to be basedmonophyletic on valve morphology, [17], but their astonishinglybut these comparisons rapid class-level did not diversification withstand scrutiny at the once base limb of morphologythe Cambrian became adds betterto the known perceived [18]. and The subsequent removal of some of these groups from the crustacean crown- or even the euarthropod puzzling magnitude of the Cambrian Explosion. crown-group [18] recalls previous proposals regarding arthropod polyphyly [22]. Arthropods are Although arguments have been presented that bradoriids are polyphyletic [5,23], Bradoriida is considered here to be monophyletic [17], but their astonishingly rapid class-level diversification at the treatedbase here of the as Cambrianmonophyletic adds to[6]. the If perceivedthis is indeed and puzzling the case, magnitude and with ofadditional the Cambrian information Explosion. regarding the limb Althoughstructure argumentsof bradoriids, have erection been presented of a ne thatw arthropodan bradoriids are class polyphyletic to accommodate [5,23], Bradoriida this clade is may be warranted.treated here as monophyletic [6]. If this is indeed the case, and with additional information regarding theWilliams limb structure and coauthors of bradoriids, [5] erectionargued ofthat a new the arthropodan bradoriid classfamilies to accommodate Beyrichonidae, this clade Bradoriidae, may Cambriidae,be warranted. Comptalutidae, Hipponicharionidae, Kunmingellidae, and Svealutidae were united by three features:Williams 1, anda bivalved coauthors shell; [5] argued2, an entire, that the continuous bradoriid latero-admarginal families Beyrichonidae, ridge Bradoriidae, or rim, and 3, postpleteCambriidae, or amplete Comptalutidae, (but not proplete) Hipponicharionidae, shields (Figure Kunmingellidae, 3). In addition, and Svealutidaecambriids and were kunmingellids united by havethree comparable features: 1,lobation a bivalved patterns shell; 2,and an entire,an anterodorsal continuous latero-admarginalcusp [5]. The lobes ridge in or cambriids rim, and 3, and postplete or amplete (but not proplete) shields (Figure3). In addition, cambriids and kunmingellids have kunmingellids may be connected by ridges. Bradoriidae, Comptalutidae, and Svealutidae all tend to comparable lobation patterns and an anterodorsal cusp [5]. The lobes in cambriids and kunmingellids have a concentration of lobes in the anterodoral region [5]. Beyrichonidae, Cambriidae, may be connected by ridges. Bradoriidae, Comptalutidae, and Svealutidae all tend to have a Hipponicharionidae,concentration of lobes and in Kunmingellidae the anterodoral region may [ 5be]. Beyrichonidae,close relatives Cambriidae, because of Hipponicharionidae, frequently conjoined, welland delimited Kunmingellidae anterior and may posterior be close relatives lobes [5]. because of frequently conjoined, well delimited anterior and posterior lobes [5].

Figure 3. Proplete, amplete, and postplete bradoriid shield pairs. Most bradoriids develop postplete shields. Anterior to the left. Asterisk (*) denotes cardinal corners; “a” denotes anterodorsal cardinal Figurecorner 3. Proplete, marginal amplete, concavity. and The postplete relative height bradoriid of each shie shieldld pairs. is measured Most bradoriids by the distance develop it extends postplete shields.from Anterior the hinge to line the (black left. horizontalAsterisk (*) line); denotes all three cardinal of the examples corners; shown “a” denotes here have anterodorsal the same shield cardinal height. Image Credit: Mark McMenamin. corner marginal concavity. The relative height of each shield is measured by the distance it extends

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Although sexual dimorphism can be problematic to identify in the fossil record, it is thought to occur in bradoriids, with females in some species having a greater carapace height in relation to carapace width [24]. Bradoriids may have had as many as nine molt stages, and their assemblages tend to be monotypic [24]. Bradoriid species are also known for their high degree of morphological variability [19]. Interpretation of bradoriids is complicated by two factors. First, generally speaking only the bivalved carapace is known for any particular species; preserved appendages are rarely seen. Most species are known only from carapace morphology; classifying bradoriids (or ostracods, for that matter) on valve morphology alone poses special challenges [18]. These challenges can be addressed in some cases by careful attention to ontogeny [25]. It has been said that carapace “morphology is a poor means of establishing the affinity of bivalved arthropods, because the bivalved shield is a feature prone to evolutionary convergence” [16]. Furthermore, the reasons for changes in nodosity (i.e., the presence of external lobes and nodes on the valves) are not well understood and the same applies to ostracods [9].

3. Cephalic Appendages in Bradoriids Bradoriids were once considered to be ancestral to modern ostracods, or classified as ostracods themselves, but the discovery of specimens with soft-bodied limb preservation at Chengjiang demonstrated that they are in fact an arthropod stem group [3,16]. Bradoriids never underwent the extreme desegmentation of the Ostracoda [3,22]. Desegmentation became nearly total in the podocopid ostracods [9]. In terms of appendage preservation and chaetotaxy, Kunmingella douvillei [3,16] is the best-known bradoriid. From anterior to posterior, the appendages consist of uniramous antennae (1), biramous appendages (2–8), and uniramous appendages (9–10) [18]. Five pairs of cephalic appendages (a1–a5) were identified [16] in Kunmingella douvillei. Although the pectinate anterior appendage structures in Kunmingella douvillei (= K. maotianshanensis) were identified as exopodite cephalic appendages (ex.c app), it seems likely that they functioned in a way similar to structures in ostracods that are of endopodite origin. For example, the modern ostracod Cypria petenensis has comparable pectinate structures projecting from its mandibular endopodite [26].

4. Bradoriid Locomotion The bradoriid hinge has no sockets nor teeth as do the beyrichiocopid and podocopid ostracods of the Ordovician [5]. The ends of the hinge at the anterior of each shield are called the cardinal corners (Figure3). Recognizing the anterior versus posterior orientation of bradoriid shields can be challenging [7], and this problem is longstanding. Charles D. Walcott remarked in 1887 [27] that it “is difficult to determine the anterior and posterior ends of the valves in many of the specimens.” Sometimes a saw-like row of teeth marks the posterior margin. Recognition of what is here called the anterodorsal cardinal corner marginal concavity helps to distinguish the anterior ends of shields, and works consistently for preplete, amplete and postplete taxa (Figure3). This feature is associated with the anterior cardinal angle as shown in Siveter and Williams [20], and is well displayed in Bradoria scrutator [20]. An excellent example of the anterodorsal cardinal corner marginal concavity is seen in preplete Dielymella recticardinalis where the anterior cardinal corner is as well drawn out into a short spine [20]—the anterodorsal cardinal corner marginal concavity clearly indicates the anterior end of the bradoriid. In cases where there is a prominent posterodorsal cardinal corner concavity as in Mongolitubulus athelios, the anterior-posterior orientation is often indicated by both the sweep of the great spines projecting from the mid-region of each shield, and also by the short spines along the posteroventral margin. The position of the hinged bradoriid carapace in life has been controversial, with some advocating that the valves were held open in a “butterfly position”, with others [28] arguing that the valves could be tightly sealed with all appendages protected inside. In Cambroarchilocus tigris gen. nov. sp. nov., Geosciences 2020, 10, 119 6 of 37 the anterior lobe is largely effaced giving an inflated look to the front of the shields; this was likely to allow sufficient space within the bivalved carapace to hold the appendages of the animal. Thus, the “tightly-enclosed” interpretation of bradoriids is likely correct, although adductor muscle scars have not been positively identified [28,29]. Cambrian arthropod fossils with conjoined bivalves that are opened out into the butterfly position may represent either shed exuviae (as occurs in Tuzoia and Isoxys) or situations where adductor musculature has experienced post-mortem loss [28]. Based on a survey of the preserved appendages that have been discovered so far, bradoriids never developed oar-like rowing appendages as in cladocerans such as Daphnia [30]. I propose here that the shields in some bradoriid genera were utilized for flap swimming, in addition to the protective function provided by closure of the two shields along a plane of commissure. The depth of each shield in comparison to its width is large in several bradoriid genera, such as Hipponicharion, Beyrichona, and Albrunnicola (see genera descriptions below). The hydrodynamically-shaped wing tip (ventral valve edge) in Beyrichona avannga with its very smooth, rounded contour shows evidence for streamlining [31]. The appendages in bradoriids [16,17] show no modification for swimming efficiency, and thus the animal using a flap of its shields for rapid escape, as in scallops, seems plausible. The delta-wing configuration of Hipponicharion skovstedi also suggests swimming by clapping of valves [31]. Beyrichona papilio, named for the butterfly in honor of its wing-like shields, has strongly acuminate (narrow) ventral shield margins and was perhaps able to “fly” through the water as may have been the case for other species in the genus Beyrichona with tall, triangular shields such as Beyrichona tinea. The same is true, perhaps even more so, of the bradoriid Pseudobeyrichona monile with its wing-shaped shields [19]. Matthoria troyensis also has a postplete shield shape well suited to shield-rowing locomotion, with a bluntly pointed extension at the ventral most part of the marginal rim [20]. The preplete configuration of the shields of Cambroarchilocus tigris gen. nov. sp. nov. suggests that shield swimming might have propelled the animal backwards comparable to the motion of a jet-propelled cephalopod. A more appropriate analogy may be a rowing motion with the shields. This can also explain why the dorsoposterior lobe is so well delimited; the posterior lobes may have functioned (with carapace closed) something like a pair of stabilizing fins (cf. cephalopod fins) during jet propulsive backwards locomotion. Sustained swimming by clapping of valves, as in the swimming file clam (Limaria spp.), is a locomotary mode that may have applied to bradoriids, especially the beyrichonids and hipponicharionids which developed particularly tall shields. The fragile file clam (Limaria fragilis) swims by opening its valves and then expelling water by closing its valves. It can swim in this fashion for five minutes or more [32]. The reconstruction of Monceretia in frontal view [33] seems poised for this type of underwater “flight”.

5. Bradoriid Developmental Biology A hypothetical allele of Antennapedia, AntpTgl, has been proposed as being responsible for [34] morphological changes in trilobites such as cephalic width changes and the development of greatly elongated pleural segments, the macropleurae [34,35]. Hughes [35] made an alternate proposal, linking the development of macropleural segments in trilobites to Abdominal-B Hox gene with expression being linked to the location of the genital opening, with its position along the animal’s anterior-posterior axis being the proximal trigger for macropleural development [35]. Unfortunately for Hughes’ Abdominal-B scheme for the development of macropleurae, if we roughly equate macropleural development with appendage development, and there exist good reasons to do so, Abdominal-B actually represses rather than expresses the development of appendages [36]. Geosciences 2020, 10, 119 7 of 37

The good reasons to equate macropleural development with appendage development are as follows. The unusual terminal cerci in Olenoides serratus are antennae-like structures that might very well be considered ectopic antennae resulting from Hox gene expression. Said gene might very well be a gene from the Antennapedia complex such as AntpTgl. Interestingly, Paradoxides grandoculus [37] lacks cerci but develops a pair of final thoracic pleurae that are greatly elongated into cerci-like structures. Incidentally, both the cerci and the terminal thoracic macropleurae in Olenoides serratus and Paradoxides grandoculus may have had synecological significance for the animals by serving as an early warning system against attack from behind. Both structures, furthermore, may have been controlled by the AntpTgl allele showing expression in the ventral part of the animal (cerci) or the dorsal (i.e., carapace) part of the animal (terminal thoracic macropleurae). The shape or “swing” of bradoriid valves comes in three versions: preplete, amplete, and postplete (Figure3). The terms refer to whether the maximum height of the shield is anterior (preplete), near the midline (amplete), or posterior (postplete). I propose here, in accordance with the AntpTgl hypothesis, that the shape of the bradoriid shield was also controlled by the AntpTgl allele in a way similar to the way that it influenced the shape of the trilobite cephalon. The influence of Antennapedia can help explain the otherwise hard to explain deep (tall) triangular to subtriangular shield shapes in the Beyrichonidae and the Hipponicharionidae. The maximum height of the shield (see Figure3) in a particular bradoriid species, in the view advocated here, was controlled by the expression of the AntpTgl allele, with the exact position of the expression on the gene along the anterior-posterior axis of the animal determining whether the shield is preplete, amplete, or postplete. For example, if the maximum shield height is anterior, the shield is proplete (Figure3, left); if the maximum shield height is central, the shield is amplete (Figure3, center); and if the maximum shield height is posterior, the shield is postplete (Figure3, left). This corresponds to the allele’s influence on the width of the cephalon in nevadiid and bristoliid trilobites [34]. The proximity of the posteroventral node to the ventral margin, e.g., adjacent as in Shangsiella versus more distant in Petrianna [33] may also be controlled by the AntpTgl allele in the same way that interocular spacing varies from state 1 to 5 and extraocular spacing varies from state 1 to 4 in nevadiid trilobites [38]. Hughes [35] argued that “Antennapedia expression is largely confined to the trunk and posterior cephalic body regions among extant arthropods” and this would accord with its influence proposed here for bradoriid shield shape. Hughes [35], citing the work of his student Webster [39], mistakenly commented “the role of AntpTgl in the development of cephalic morphology is inconsistent with current knowledge of olenellid ontogeny.” Rather, if we accept that Antennapedia can influence the head region as well (as apparent in the eponymous Drosophila mutant [40]), the position of the genal and metagenal spines in Nephrolenellus multinodus through ontogeny is in accord with predictions of the AntpTgl model, especially if you consider the enhanced width of the first glabellar lobe in mature individuals of this species.

6. Bradoriid Genera Following is a review of accepted bradoriid genera (plus a few unnamed forms), with family assignment (if known) and geological ranges listed for each genus. Acutobalteus Betts et al. 2017 [41]; Range: early Cambrian, Dailyatia odyssei Zone; Hipponicharionidae; In Acutobalteus valves, the two lobes merge distally, forming a single lobe [31]. Albrunnicola Martinsson, 1979 [42]; Hipponicharionidae; Range: Stage 3 to Drumian. This genus was initially given the name Longispina by D. Andres in 1969 [43]. In an amusingly-written short note published by Anders Martinsson in 1979 [42], this name was shown to have a senior homonym, a brachiopod from the Middle Devonian. Martinsson thus introduced the replacement name Albrunnicola. According to Martinsson [42], the “name is derived from the root albrunn- in the name of the type locality on the Isle of Öland and -cola (Latin), inhabitant. Note particularly that the gender is masculine (hence Albrunnicola oelandicus) and that the short penultimate syllable places the stress on the connecting vowel i.” In this genus, the valves are as tall or taller than the hinge line is Geosciences 2020, 10, 119 8 of 37

long. A thin flat margin runs from one edge of the hinge to the other. Lobes may slightly overhang the hinge area. Albrunnicola (Figure4) “is widespread hipponicharionid genus characterized by a strongly developed anterodorsal lobe and a weaker, node-like posterodorsal lobe” [6]. Albrunnicola is distinguished from other hipponicharionids by “a weakly developed posterior lobe, with both lobes Geosciences 2020, 10, x FOR PEER 8 of 37 restricted to the dorsal half of the valve” [25]. A. bengtsoni from the Wirrapowie Limestone in the Flinders TheRanges, genus Australia occurs isin a “weaklythe Cambrian postplete Series bradoriid 2 Bastion with Formation subtriangular of lateralGreenland outline” [31]. [ 6Albrunnicola]. The genus bengtsonioccurs in (Figure the Cambrian 4) has Seriesbeen reported 2 Bastion from Formation glacial of erratic Greenland clasts [from31]. Albrunnicola the Transantarctic bengtsoni Mountains(Figure4) [44].has beenThe reportedtype species from of glacial the genus erratic is clastsmiddle from Cambrian the Transantarctic (Cambrian Mountains Series 3, Wuliuan; [44]. The Albrunnicola type species oelandicusof the genus [43]), is middle and occurs Cambrian in Öland, (Cambrian Sweden, Series in 3, th Wuliuan;e BorgholmAlbrunnicola Formation oelandicus [31]. Interestingly,[43]), and occurs the subspeciesin Öland, Sweden, Albrunnicola in the oelandicus Borgholm Formationmaroccanus [ 31Hinz-Schallreuter,]. Interestingly, the 1993 subspecies has beenAlbrunnicola reported oelandicusfrom the centralmaroccanus Anti-AtlasHinz-Schallreuter, of Morocco [19]. 1993 Albrunnicola has been reported has an frominteresting the central paleobiogeographic Anti-Atlas of Moroccodistribution, [19]. occurringAlbrunnicola in hasLaurentia, an interesting Australia, paleobiogeographic and Antarctica distribution,[31]. The genus occurring is synonymous in Laurentia, with Australia, Beyrichona and chinensisAntarctica [25]. [31 ]. The genus is synonymous with Beyrichona chinensis [25].

Figure 4. Albrunnicola bengtsoni. Paired shields shown in butterfly position. Anterior to left. Length of Figureshield 1.54. Albrunnicola mm. Abbreviations: bengtsoniadn. Paired, anterodorsal shields shown node; inamr butterfly, admarginal position. rim; Anteriorpdn, posterodorsal to left. Length node. of shieldImage 1.5 Credit: mm. Abbreviations: Mark McMenamin. adn, anterodorsal node; amr, admarginal rim; pdn, posterodorsal node. Image Credit: Mark McMenamin. Almazina Melnikova, 2003 [45]; Range: Cambrian. Almazina, from Malyi Karatau, Russia, differsAlmazina from Euzepaera Melnikova,by having2003 [45]; smaller, Range: more Cambrian. densely Almazina distributed, from pores Malyi [6]. Karatau, Russia, differs from AltajanellaEuzepaera byMelnikova, having smaller, 1992 [46 more]; Range: densely Late distributed Pabian to early pores Stage [6]. 9. Earlier thought to have true ostracodAltajanella affinities Melnikova, [5], this 1992 tiny [46]; bradoriid Range: is Late now Pabian thought to toearly be homoplasicStage 9. Earlier on ostracodthought to “body have plantrue ostracod2” [2]. affinities [5], this tiny bradoriid is now thought to be homoplasic on ostracod “body plan 2” [2]. AlutaAluta Matthew,Matthew, 1896 [47]; [47]; Alutidae; Range: Early Early Cambrian, Cambrian, Series Series 2. 2. AlutaAluta differsdiffers from from BradoriaBradoria byby the the presence of a broadbroad marginalmarginal rimrim of of equal equal width width from from anterior anterior to to posterior posterior [21 [21].]. Aluta Alutaoccurs occurs in inthe the Niutitang Niutitang Formation Formation of of the the Yangtze Yangtze Platform Platform of Guizhou,of Guizhou, China. China. AlutellaAlutella KobayashiKobayashi & & Kato Kato 1951 1951 [48]; [48]; Comptalutidae; Comptalutidae; Range: Range: Middle Middle Stage Stage 3 3 to to mid mid Wuliuan. Wuliuan. AlutellaAlutella has been reported from Scania, Sweden [48]. [48]. AmphikeropsisAmphikeropsis Topper, Skovsted,Skovsted,Brock Brock and and Paterson, Paterson, 2007 2007 [25 [25]]; Range:; Range: Late Late Stage Stage 3. 3. This This genus genus is isendemic endemic to to South South Australia Australia [25 [25].]. Anabarochilina Abushik, 1960 [49]; Svealutidae; Range: Late Stage 3 (Elliptocephala asaphoides fauna, New York) to late Stage 10. Anabarochilina is an oval-elongate, postplete to subamplete, smooth bradoriid with a fairly wide marginal rim, a well-developed hinge line and up to three nodes [20]. A partially exfoliated valve of Anabarochilina sp. from the Middle Cambrian of Kazakhstan shows what are interpreted as integumental hemolymph networks, as does Anabarochilina primordialis from the middle Cambrian of Västergötland, Sweden [2]. The genus represents a cosmopolitan, presumably pelagic taxon [5,50]. A single prominent node per valve is present in the cosmopolitan species Anabarochilina australis [51]. Anabarochilina primordialis may possess an enlarged brood chamber. One species of the genus may have lived at southern hemisphere high latitude (70° S) sea surface habitat in the Middle Cambrian (Lejopyge laevigata Biozone) [5].

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Anabarochilina Abushik, 1960 [49]; Svealutidae; Range: Late Stage 3 (Elliptocephala asaphoides fauna, New York) to late Stage 10. Anabarochilina is an oval-elongate, postplete to subamplete, smooth bradoriid with a fairly wide marginal rim, a well-developed hinge line and up to three nodes [20]. A partially exfoliated valve of Anabarochilina sp. from the Middle Cambrian of Kazakhstan shows what are interpreted as integumental hemolymph networks, as does Anabarochilina primordialis from the middle Cambrian of Västergötland, Sweden [2]. The genus represents a cosmopolitan, presumably pelagic taxon [5,50]. A single prominent node per valve is present in the cosmopolitan species Anabarochilina australis [51]. Anabarochilina primordialis may possess an enlarged brood chamber. One species of the genus may have lived at southern hemisphere high latitude (70◦ S) sea surface habitat in the Middle GeosciencesCambrian 2020 (Lejopyge, 10, x FOR laevigata PEER Biozone) [5]. 9 of 37 Annge Smith et al. 2014 [52]; Range: Cambrian Series 3, Stage 5. Annge iperte occurs in the Giles CreekAnnge Dolostone Smith in etAustralia. al. 2014 [52]; Range: Cambrian Series 3, Stage 5. Annge iperte occurs in the Giles CreekAntihipponicharion Dolostone in Australia.Huo & Shu, 1985 [53]; Indianidae; Range: Cambrian. AntihipponicharionAristaluta Öpik, 1961 Huo [54 &]; Shu, Comptalutidae; 1985 [53]; Indianidae; Range: Late Range: Wuliuan Cambrian. to mid-Guzhangian. AristalutaAuriculatella Öpik,Tan, 1961 1980 [54]; [55 ];Comptalutidae; Cambriidae; Range: Range: Mid Late to Wuliuan late part to of mid-Guzhangian. early Stage 3. Auriculatella is distinguishedAuriculatella by aTan, posterodorsal 1980 [55]; ridgeCambriidae; that connects Range: to Mid the anterodorsalto late part of ridge early by Stage means 3. ofAuriculatella a connecting is distinguishedridge, and also by by a presence posterodorsal of an anterodorsal ridge that conne nodects [38 ].toAuriculatella the anterodorsal typica occursridge by in themeansAbadiella of a connectingBiozone of Southridge, Chinaand also [5]. by presence of an anterodorsal node [38]. Auriculatella typica occurs in the AbadiellaAustralopsis BiozoneHinz-Schallreuter, of South China [5]. 1993 [56]; Range: Late Wuliuan. AustralopsisBeyrichona Matthew, Hinz-Schallreuter, 1886 [57]; 1993 Beyrichonidae; [56]; Range: Range: Late Wuliuan. Late Stage 3 to Ordovician (Tremadoc). BeyrichonaBeyrichonawas firstMatthew, described 1886 from[57]; AvaloniaBeyrichonidae; by Matthew Range: inLate 1886 Stage [57]. 3 Theto Ordovician genus is known (Tremadoc). for its Beyrichonasubtriangular was carapace first described [7]. Beyrichona from Avaloniais a characteristic by Matthew genus in 1886 (Figures [57].5 The–7) ofgenus the Cambrian is known Seriesfor its subtriangular2–3 Hanford Brook carapace Formation [7]. Beyrichona of New is Brunswick a characteristic [31]. It genus has also (Figures been assigned5, 6, 7) of to theNeokunmingella Cambrian Series[6]. Beyrichona2–3 Hanfordis considered Brook Formation to be characteristic of New Brunswick of shallow [31]. water It has deposits also been [31]. Beyrichonaassigned to avannga Neokunmingella(Figure5) [6].can Beyrichona be hard to distinguishis considered from to be some characteristic species of Albrunnicolaof shallow water[31]. Beyrichonadeposits [31].is a Beyrichona very long rangingavannga (Figurebradoriid, 5) can surviving be hard into to distinguish the Ordovician from until some going species extinct of Albrunnicola at the end of[31]. the Beyrichona Tremadocian is a very (Angelina long rangingsedgwickii bradoriid,Biozone) surviving [2]. into the Ordovician until going extinct at the end of the Tremadocian (Angelina sedgwickii Biozone) [2].

Figure 5. Beyrichona avanga. Paired shields shown in butterfly position. Anterior to left. Scale bar Figure 5. Beyrichona avanga. Paired shields shown in butterfly position. Anterior to left. Scale bar 200 200 microns. Abbreviations: adn, anterodorsal node; amr, admarginal rim; pdn, posterodorsal node. microns. Abbreviations: adn, anterodorsal node; amr, admarginal rim; pdn, posterodorsal node. Image Credit: Mark McMenamin. Image Credit: Mark McMenamin.

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Figure 6. Beyrichona papilio. Paired shields shown in butterfly position. Anterior to left. Length of Figureshield 3.6 6. Beyrichonamm. Abbreviations: papilio. Paired adn, anterodorsal shields shown node; in butterfly pdn, posterodorsal position. Anterior node. Image to left. Credit: Length Mark of FigureshieldMcMenamin. 3.66. Beyrichona mm. Abbreviations: papilio. Pairedadn shields, anterodorsal shown in node; butterflypdn ,position. posterodorsal Anterior node. to left. Image Length Credit: of shieldMark McMenamin.3.6 mm. Abbreviations: adn, anterodorsal node; pdn, posterodorsal node. Image Credit: Mark McMenamin.

Figure 7. Beyrichona tinea. Anterior to left. Length of shield 3.2 mm. Abbreviations: a, anterodorsal cardinal Figure 7. Beyrichona tinea. Anterior to left. Length of shield 3.2 mm. Abbreviations: a, anterodorsal marginal concavity; adn, anterodorsal node; pdn, posterodorsal node. Image Credit: Mark McMenamin. cardinal marginal concavity; adn, anterodorsal node; pdn, posterodorsal node. Image Credit: Mark FigureBiaurinaMcMenamin. 7. BeyrichonaHinz-Schallreuter, tinea. Anterior 1993 to [ 56left.]; ?BradoriidaeLength of shield [58 3.2]; Range:mm. Abbreviations: Late Wuliuan. a, anterodorsal This genus has beencardinal reported marginal to have concavity; a doublure, adn,in anterodorsal which case node; it would pdn, beposterodorsal classified asnode. a phosphatocopid, Image Credit: Mark but the presenceMcMenamin.Biaurina of a doublureHinz-Schallreuter, is doubted 1993 [6], so[56]; it is ?Bra includeddoriidae here [58]; as aRange: bradoriid Late based Wuliuan. on a lobation This genus pattern has thatbeen matches reported that to commonlyhave a doublure, seen in in Bradoriida. which case Surface it would ornamentation be classified in asBiaurina a phosphatocopid, punctata consists but the of Biaurina Hinz-Schallreuter, 1993 [56]; ?Bradoriidae [58]; Range: Late Wuliuan. This genus has porespresence open of to a doublure the exterior is doubted [6]. [6], so it is included here as a bradoriid based on a lobation pattern been reported to have a doublure, in which case it would be classified as a phosphatocopid, but the that Bicarinellatamatches thatStigall, commonly 2008 seen [59]; in Hipponicharionidae; Bradoriida. Surface Range:ornamentation Late Stage in Biaurina 3 to early punctata Stage consists 4 (with presence of a doublure is doubted [6], so it is included here as a bradoriid based on a lobation pattern question).of pores openBicarinellata to the exterioris a replacement [6]. name for Bicarinella Rode, Lieberman and Rowell, 2003 which that matches that commonly seen in Bradoriida. Surface ornamentation in Biaurina punctata consists was preoccupiedBicarinellata byStigall, two (2008sic) gastropod[59]; Hipponicharionidae; genus names. Bicarinellata Range: Late evansi Stage(Figure 3 to early8) occurs Stage in 4 lower (with of pores open to the exterior [6]. Cambrianquestion). strataBicarinellata of the is Pensacola a replacement Mountains, name for East Bicarinella Antarctica Rode, [6, 24Lieberman]. The posterior and Rowell, lobe 2003 or node which in Bicarinellata Stigall, 2008 [59]; Hipponicharionidae; Range: Late Stage 3 to early Stage 4 (with Bicarinellatawas preoccupiedis close by to two the edge(sic) gastropod of the valve genus [31]. names. Bicarinellata evansi (Figure 8) occurs in lower question).Cambrian Bicarinellata strata of the is aPensacola replacement Mountains, name for East Bicarinella Antarctica Rode, [6,24]. Lieberman The posterior and Rowell, lobe 2003 or node which in wasBicarinellata preoccupied is close by totwo the (sic edge) gastropod of the valve genus [31]. names. Bicarinellata evansi (Figure 8) occurs in lower Cambrian strata of the Pensacola Mountains, East Antarctica [6,24]. The posterior lobe or node in Bicarinellata is close to the edge of the valve [31].

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FigureFigure 8. Bicarinellata 8. Bicarinellata evansi evansi. Anterior. Anterior to to left. left. Letter Letter “a”“a” denotes denotes anterodorsal anterodorsal cardinal cardinal corner corner marginal marginal concavity. Length of shield 1.5 mm. Abbreviations: a, anterodorsal cardinal marginal concavity; adn, Figureconcavity. 8. Bicarinellata Length of evansi shield. Anterior 1.5 mm. Abbreviations:to left. Letter “a”a, anterodorsal denotes anterodorsal cardinal marginal cardinal concavity; corner adnmarginal, anterodorsalanterodorsal node; node; pdnpdn, posterodorsal, posterodorsal node. ImageImage Credit: Credit: Mark Mark McMenamin. McMenamin. concavity. Length of shield 1.5 mm. Abbreviations: a, anterodorsal cardinal marginal concavity; adn, anterodorsal node; pdn, posterodorsal node. Image Credit: Mark McMenamin. BradoriaBradoria Matthew,Matthew, 1899 1899 [60] [60 (Figure] (Figure 9);9); Bradoriidae; Bradoriidae; Range: Range: Late Late Stage 3 to early Wuliuan;Wuliuan; mid Wuliuanmid Wuliuan to late Stage to late 9 Stage (with 9 question). (with question). Surface Surface ornamentation ornamentation in Bradoria in Bradoria scrutator scrutator consistsconsists of of pores Bradoria Matthew, 1899 [60] (Figure 9); Bradoriidae; Range: Late Stage 3 to early Wuliuan; mid thatpores do not that penetrate do not penetrate the shell the and shell can and only can be only seen be seenwhere where the shell the shell is exfoliated is exfoliated [6]. [6 ]. Wuliuan to late Stage 9 (with question). Surface ornamentation in Bradoria scrutator consists of pores that do not penetrate the shell and can only be seen where the shell is exfoliated [6].

Figure 9. Bradoria sp. Anterior to left. Length of shield 1.28 mm. Image Credit: Mark McMenamin. Figure 9. Bradoria sp. Anterior to left. Length of shield 1.28 mm. Image Credit: Mark McMenamin. Bullaluta Copeland, 1986 [61]; Bradoriidae; Range: Late Guzhangian. Bullaluta is a western Figure 9. Bradoria sp. Anterior to left. Length of shield 1.28 mm. Image Credit: Mark McMenamin. NewfoundlandBullaluta Copeland, bradoriid 1986 of Furongian [61]; Bradoriidae; (Late Cambrian) Range: age [Late19]. It Guzhangian. has a non-lobate Bullaluta shield [19 is], witha western a pustulose appearance where the valve is exfoliated [20]. Like Hipponicharionidae, the Beyrichonidae Newfoundland bradoriid of Furongian (Late Cambrian) age [19]. It has a non-lobate shield [19], with haveBullaluta a subtriangular Copeland, shield1986 [61]; [25]. Bradoriidae; The anterior Range: and posterior Late Guzhangian. lobes extend Bullaluta further ventrallyis a western a pustulose appearance where the valve is exfoliated [20]. Like Hipponicharionidae, the Newfoundlandin the Hipponicharionidae bradoriid of Furongian than in the (Late Beyrichonidae. Cambrian) age Posterior [19]. It has sulcation a non-lobate often occurs shield in [19], the with Beyrichonidae have a subtriangular shield [25]. The anterior and posterior lobes extend further a pustuloseBeyrichonidae appearance [25]. where the valve is exfoliated [20]. Like Hipponicharionidae, the ventrally in the Hipponicharionidae than in the Beyrichonidae. Posterior sulcation often occurs in the BeyrichonidaeCambria haveNeckaja a subtriangular & Ivanova 1956 shield [62]; Cambriidae; [25]. The Range:anterior Stage and 3. posteriorCambria (Figures lobes extend10 and 11further) Beyrichonidae [25]. ventrallyhas a largein the carapace Hipponicharionidae with an inflected than hinge in linethe [Beyrichonidae.7]. The terminal Posterior lobes are divided sulcation by aoften sulcus, occurs and ain the papillateCambriasurface Neckaja may & beIvanova present 1956 [7]. The[62]; anterodorsal Cambriidae; node Range: is linked Stage to 3. the Cambria posterodorsal (Figures node 10, by11) has Beyrichonidae [25]. a largea connecting carapace ridge;with an anterodorsalinflected hinge ridge line is present[7]. The [ 33terminal]. Formerly lobes assigned are divided with questionby a sulcus, to the and a Cambria Neckaja & Ivanova 1956 [62]; Cambriidae; Range: Stage 3. Cambria (Figures 10, 11) has papillateHipponicharionidae surface may be [7], present it is now [7]. the The eponymous anterodors genusal node for the is Cambriidae linked to the [25]. posterodorsal The Montagne node Noir by a a large carapace with an inflected hinge line [7]. The terminal lobes are divided by a sulcus, and a connecting(Pardailhan ridge; Formation) an anterodorsal of southern Franceridge hasis presen producedt [33].Cambria Formerly danvizcainia assigned[19,33]. withCambria question melnikovi to the papillate surface may be present [7]. The anterodorsal node is linked to the posterodorsal node by a Hipponicharionidae(Figure 10) from the[7], Atdabanianit is now the of eponymous eastern Siberia genus shows for whatthe Cambriidae are interpreted [25]. asThe integumental Montagne Noir connectinghemolymph ridge; networks an anterodorsal [2]. ridge is present [33]. Formerly assigned with question to the (Pardailhan Formation) of southern France has produced Cambria danvizcainia [19,33]. Cambria Hipponicharionidae [7], it is now the eponymous genus for the Cambriidae [25]. The Montagne Noir melnikovi (Figure 10) from the Atdabanian of eastern Siberia shows what are interpreted as (Pardailhan Formation) of southern France has produced Cambria danvizcainia [19,33]. Cambria integumental hemolymph networks [2]. melnikovi (Figure 10) from the Atdabanian of eastern Siberia shows what are interpreted as integumental hemolymph networks [2].

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Figure 10. Cambria melnikovi. Anterior to left. Scale bar 1 mm. Abbreviations: adn, anterodorsal node; Figurecr, connecting 10. Cambria ridge; melnikovi dc, dorsal. Anterior cusp. Image to left. Credit: Scale bar Mark 1 mm. McMenamin. Abbreviations: adn, anterodorsal node; crFigure, connecting 10. Cambria ridge; melnikovidc, dorsal. Anterior cusp. Image to left. Credit: Scale bar Mark 1 mm. McMenamin. Abbreviations: adn, anterodorsal node; cr, connecting ridge; dc, dorsal cusp. Image Credit: Mark McMenamin.

Figure 11. Cambria sibirica. Anterior to left. Length of shield 3 mm. Abbreviations: adn, anterodorsal node; dc, dorsal cusp; pdn, posterodorsal node. Image Credit: Mark McMenamin. Figure 11. Cambria sibirica. Anterior to left. Length of shield 3 mm. Abbreviations: adn, anterodorsal node; dc, dorsal cusp; pdn, posterodorsal node. Image Credit: Mark McMenamin. CambroarchilocusFigure 11. Cambria sibiricanov.. gen.;Anterior Hipponicharionidae; to left. Length of shield Range: 3 mm. Abbreviations: Late Stage 3.adn, Seeanterodorsal new genus descriptionnode; dc below., dorsal cusp; pdn, posterodorsal node. Image Credit: Mark McMenamin. CapricambriaCambroarchilocusHinz, nov. 1991 gen.; [63]; Hipponicharionidae; Monasteriidae; Range: Range: Late Late Wuliuan. Stage A3. spinySee new bradoriid. genus description below. CedocamiaCambroarchilocusHinz-Schallreuter, nov. gen.; Hipponicharionidae; 1993 [56]; Comptalutidae; Range: Range: Late Stage Late 3. Wuliuan. See new genus description Capricambria Hinz, 1991 [63]; Monasteriidae; Range: Late Wuliuan. A spiny bradoriid. below.Chegetella Kanygin, 1977 [64]; Range: middle Ordovician. This spinose bradoriid occurs in Siberian Cedocamia Hinz-Schallreuter, 1993 [56]; Comptalutidae; Range: Late Wuliuan. middleCapricambria Ordovician Hinz, strata 1991 [6,13 ].[63];Chegetella Monasteriidae; chegitunica Range:is the correctLate Wuliuan. species spelling, A spiny notbradoriid. “C. chegetunica”. Chegetella Kanygin, 1977 [64]; Range: middle Ordovician. This spinose bradoriid occurs in ChuanbeiellaCedocamia Hinz-Schallreuter,Huo & Peng (in Huo 1993 & [56]; Shu), Comp 1985talutidae; [53]; Cambriidae; Range: Late Range: Wuliuan. Cambrian. Siberian middle Ordovician strata [6,13]. Chegetella chegitunica is the correct species spelling, not “C. ComptalutaChegetella Kanygin,Öpik, 1968 1977 [65]; Comptalutidae;[64]; Range: middle Range: Ordovician. Middle Stage This 3 to Drumian.spinose bradoriidComptaluta occursconsists in chegetunica”. ofSiberian small, decidedlymiddle Ordovician postplete strata bradoriids; [6,13]. the Chegetella submedian chegitunica node is is prominent the correct [ 21species]. Comptaluta spelling, kailiensis not “C. Chuanbeiella Huo & Peng (in Huo & Shu), 1985 [53]; Cambriidae; Range: Cambrian. andchegetunica”.C. inflata occur in the Balang Formation of Zhenyuan County, Guizhou Province, South China [21]. Comptaluta Öpik, 1968 [65]; Comptalutidae; Range: Middle Stage 3 to Drumian. Comptaluta CordubiellaChuanbeiellaHinz-Schallreuter, Huo & Peng (in Huo Gozalo & Shu), & Liñ1985án, [53]; 2008 Cambriidae; [50]; Cambriidae; Range: Cambrian. Range: Stage 3, early. consists of small, decidedly postplete bradoriids; the submedian node is prominent [21]. Comptaluta CordubiellaComptaluta pedrochensis Öpik,(Figure 1968 [65]; 12) of Comptalutidae; southern Spain [Range:50](Lemdadella Middle perejoni Stage Biozone,3 to Drumian. late Issendalenian, Comptaluta kailiensis and C. inflata occur in the Balang Formation of Zhenyuan County, Guizhou Province, South belowconsists the ofEoredlichia small, decidedlytrilobite postplete first appearance bradoriids; datum) the submedian is one of the node oldest is prominent bradoriids [21]. from Comptaluta Western China [21]. Gondwanakailiensis and [19 C.]. inflata In Cordubiella occur in the pedrochensis Balang Formation, the nodular of Zhenyuan anterior County, lobe is “located Guizhou at Province, inner margin South Cordubiella Hinz-Schallreuter, Gozalo & Liñán, 2008 [50]; Cambriidae; Range: Stage 3, early. ofChina anterodorsal [21]. field, posterior lobe ridge-like and extending from posterodorsal to central field. Cordubiella pedrochensis (Figure 12) of southern Spain [50] (Lemdadella perejoni Biozone, late ConnectingCordubiella lobe distinct”Hinz-Schallreuter, [50]. These Gozalo lobes are & moreLiñán, pronounced 2008 [50]; thanCambriidae; in Cambria Range:. The carapaceStage 3, inearly. this Issendalenian, below the Eoredlichia trilobite first appearance datum) is one of the oldest bradoriids speciesCordubiella reaches pedrochensis to 7 mm in(Figure length. 12) of southern Spain [50] (Lemdadella perejoni Biozone, late from Western Gondwana [19]. In Cordubiella pedrochensis, the nodular anterior lobe is “located at inner Issendalenian, below the Eoredlichia trilobite first appearance datum) is one of the oldest bradoriids margin of anterodorsal field, posterior lobe ridge-like and extending from posterodorsal to central from Western Gondwana [19]. In Cordubiella pedrochensis, the nodular anterior lobe is “located at inner field. Connecting lobe distinct” [50]. These lobes are more pronounced than in Cambria. The carapace margin of anterodorsal field, posterior lobe ridge-like and extending from posterodorsal to central in this species reaches to 7 mm in length. field. Connecting lobe distinct” [50]. These lobes are more pronounced than in Cambria. The carapace in this species reaches to 7 mm in length.

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Figure 12. Cordubiella pedrochensis. Anterior to left. Length of shield 5.1 mm. Abbreviations: adn, anterodorsalFigure 12. Cordubiella node; cr, connectingpedrochensis ridge;. Anteriorpdn, posterodorsalto left. Length node. of shield Image 5.1 Credit: mm. MarkAbbreviations: McMenamin. adn, anterodorsal node; cr, connecting ridge; pdn, posterodorsal node. Image Credit: Mark McMenamin. Dictyocharion Jones & Kruse 2009 [58]; Hipponicharionidae; Range: Middle Cambrian. A subtriangularDictyocharion bradoriid Jones & withKruse a coarse2009 [58]; polygonal Hipponicharionidae; valve ornamentation Range: consistingMiddle Cambrian. of rounded A ridgessubtriangular from the bradoriid Thorntonia with Limestone a coarse ofpolygonal the Georgina valve Basin, ornamentation Northern Territory,consisting Australia of rounded [58 ].ridges fromDielymella the ThorntoniaUlrich Limestone and Bassler, of the 1931 Georgina [66]; family Basin, unknown Northern [ 5Territory,]; Range: Australia Wuliuan, [58]. with question StagesDielymella 3, 4, and Ulrich Drumian andto Bassler, late Stage 1931 9. [66];Dielymella’s family unknownlarge preplete, [5]; Range: punctate Wuliuan, shields with are elongate.question AStages short 3, anterior 4, and Drumian spine is present to late [Stage20]. Dielymella? 9. Dielymella’soccurs large in thepreplete, Montezuman punctate Stage shields (Cambrian are elongate. Stage A 3) inshort the anterior Montezuma spine Range is present and Indian [20]. Dielymella? Springs Canyon occurs sections in the Montezuman in Nevada, USA Stage [67 ],(Cambrian and a comparable Stage 3) specimenin the Montezuma occurs in Range Sonora, and M Indianéxico (see Springs below). Canyon sections in Nevada, USA [67], and a comparable specimenDietmarandresia occurs in Sonora,Hinz-Schallreuter, México (see 2008 below). [68]; Hipponicharionidae; Range: Middle to late Drumian (withDietmarandresia question). This Hinz-Schallreuter, is a new name for 2008Andresia [68];Hinz-Schallreuter, Hipponicharionidae; 1993, Range: a name Middle preoccupied to late by AndresiaDrumianStephenson, (with question). 1921 [69 This]. This is genus a new is known name forfor its Andresia “confluent Hinz-Schallreuter, anterior and posterior 1993, lobes” a name [25]. preoccupiedDorispina byHinz-Schallreuter, Andresia Stephenson, 1993 1921 [56]; family[69]. This uncertain genus is [58 known]; Range: for Lateits “confluent Wuliuan. anterior and posteriorDubianella lobes”Shu, [25]. 1990 [70]; Duibianellidae; Range: Middle Stage 3; with question to early Drumian. The valvesDorispina of DubianellaHinz-Schallreuter,are covered 1993 in [56]; nodes, family giving uncertain valves [58]; an irregularRange: Late lumpy Wuliuan. aspect that is very reminiscentDubianella of one Shu, variant 1990 of[70]; the BelgianDuibianellidae; Oligocene Range: ostracod MiddleCyprideis Stage(Goerlichia 3; with) williamsonianaquestion to early[71]. InDrumian. both cases, The wevalves might of Dubianella ask if some are type covered of parasite in nodes, or endobiontgiving valves has an triggered irregular deformity lumpy aspect in valve that surfaceis very morphology.reminiscent Aof fewone spines variant may of also the be Belgian present, Oligocene and these mayostracod be covered Cyprideis by a(Goerlichia scale-like) ornamentationwilliamsoniana [71]. as seen In both in the cases, spines we ofmightMongolitubulus ask if some. typeDubianella of parasiteis known or endobiont from both has Siberia triggered and China.deformity As Dubianellain valve surfaceresembles morphology. juveniles A of fewSpinospitella spines may[6], also it is be inferred present, here and to these be a neotenous may be covered taxon. by a Emeiellascale-likeLi, ornamentation 1975 [72]; Kunmingellidae; as seen in the Range: spines Mid of Mongolitubulus to late part of early. Dubianella Stage 3. is Thisknown kunmingellid from both (SiberiaEmeiella andsp.) China. has been As reported Dubianella from resembles the Jince Formationjuveniles of of Spinospitella the Czech Republic [6], it is [19 inferred]. One ofhere the earliestto be a bradoriids,neotenous taxon.Emeiella venusta occurs in the Abadiella Biozone of South China [5]. EozhexiellaEmeiella Li, Betts1975 [72]; et al. Kunmingellidae; 2017 [41]; Range: Range: early Mid Cambrian, to late partDailyatia of early Stage odyssei 3. ThisZone. kunmingellidEozhexiella adnyamathanha(Emeiella sp.) hasis an been Australian reported species. from the Jince Formation of the Czech Republic [19]. One of the earliestEpactridion bradoriids,Bengtson Emeiella invenusta Bengtson occurs et inal. the 1990 Abadiella [73]; Biozone Monasteriidae; of South China Range: [5]. Stage 3, early. EpactridionEozhexiella portax Bettshas punctaeet al. 2017 that open[41]; toRange: the exterior early Cambrian, [6]. The punctae Dailyatia in this odyssei species Zone. are particularlyEozhexiella prominentadnyamathanha in early is an instars Australian [73]. Bengtsonspecies. [73] interpreted the end of Epactridion portax with projecting spinesEpactridion as its anterior Bengtson (also renderingin Bengtson ita et postplete al. 1990 [73]; form). Monasteriidae; The anterior versusRange: posterior Stage 3, early. ends ofEpactridion bivalved arthropodportax has punctae shields can that be open diffi cultto the to exterior accurately [6]. ascertain The punctae [7], butin this Bengtson’s species are [73 ]particularly interpretation prominent is likely correctin early considering instars [73]. theBengtson slight concavity[73] interpreted in the the shield end margin of Epactridion between portax the cardinal with projecting corner and spines spine as (theits anterior anterodorsal (also cardinalrendering marginal it a postplete concavity). form). The anterior versus posterior ends of bivalved arthropodEremos shieldsHinz-Schallreuter, can be difficult 1993 to [74 accurately]; Svealutidae; ascertain A cosmopolitan, [7], but Bengtson’s presumably [73] pelagic interpretation taxon [50 is]. Eremoslikely correct australis consideringis synonymous the slight with concavityAnabarochilina in the australis shield [margin51]. between the cardinal corner and spine (the anterodorsal cardinal marginal concavity). Eremos Hinz-Schallreuter, 1993 [74]; Svealutidae; A cosmopolitan, presumably pelagic taxon [50]. Eremos australis is synonymous with Anabarochilina australis [51].

Geosciences 2020, 10, x FOR PEER 14 of 37 Geosciences 2020, 10, 119 14 of 37 GeosciencesEuzepaera 2020, 10 Shu,, x FOR 1990 PEER [70]; Zhexiellidae; Range: Stage 3; with question to Furongian late Stage14 of 379. Euzepaera has a punctate shell with the pores sealed on the inside by domal pads [6]. The pad domes Euzepaera Shu, 1990 [70]; Zhexiellidae; Range: Stage 3; with question to Furongian late Stage 9. haveEuzepaera flattened Shu,tops, 1990 implying [70]; Zhexiellidae; that the valve Range: had an Stage inner 3; layerwith questionsurrounding to Furongian the pads thatlate Stagewas not 9. Euzepaera has a punctate shell with the pores sealed on the inside by domal pads [6]. The pad domes Euzepaerapreserved. has The a punctategenus is shelldistinguished with the pores by the sealed absence on theof easilyinside discernedby domal padsridges [6]. or The lobes, pad but domes a V- have flattened tops, implying that the valve had an inner layer surrounding the pads that was not haveshaped flattened anterodorsal tops, implying sulcus isthat present the valve [6]. hadEuzepaera an inner sp. layer (Figure surrounding 13) occurs the in pads the thatWirrapowie was not preserved. The genus is distinguished by the absence of easily discerned ridges or lobes, but a V-shaped preserved.Limestone Thein the genus Flinders is distinguished Ranges, Australia by the [28]. absence of easily discerned ridges or lobes, but a V- anterodorsal sulcus is present [6]. Euzepaera sp. (Figure 13) occurs in the Wirrapowie Limestone in the shaped anterodorsal sulcus is present [6]. Euzepaera sp. (Figure 13) occurs in the Wirrapowie Flinders Ranges, Australia [28]. Limestone in the Flinders Ranges, Australia [28].

Figure 13. Euzepaera sp. Anterior to left. Scale bar 100 microns. Abbreviation: adn, anterodorsal node. Figure 13. Euzepaera sp. Anterior to left. Scale bar 100 microns. Abbreviation: adn, anterodorsal node. ImageImage Credit:Credit: MarkMark McMenamin.McMenamin. Figure 13. Euzepaera sp. Anterior to left. Scale bar 100 microns. Abbreviation: adn, anterodorsal node. FlemingopsisImageFlemingopsis Credit: JonesMarkJones McMenamin. && McKenzie,McKenzie, 19811981 [[75];75]; Range:Range: LateLate WuliuanWuliuan toto Drumian.Drumian. FlemingopsisFlemingopsis isis aa replacementreplacement namename forfor FlemingiaFlemingia.. ThisThis bradoriidbradoriid hashas aa morphologicallymorphologically simplesimple shieldshield andand couldcould bebe confusedconfusedFlemingopsis withwithHoulongdongella Houlongdongella Jones & McKenzie,,,Zepaera Zepaera 1981and and [75];Quetopsis Quetopsis Range:[ [25].25 Late]. Wuliuan to Drumian. Flemingopsis is a replacementFlumenoglaciesFlumenoglacies name forPeelPeel Flemingia && StrengStreng. This 20152015 bradoriid [76[76];]; Hipponicharionidae;hasHipponicharionidae; a morphologically Range: Range:simple shieldCambrian and could Series be 3.3. FlumenoglaciesconfusedFlumenoglacies with Houlongdongellaisis aa hipponicharionidhipponicharionid, Zepaera bradoriidbradoriid and Quetopsis fromfrom [25]. BritishBritish ColumbiaColumbia andand NorthNorth GreenlandGreenland fromfrom CambrianCambrianFlumenoglacies SeriesSeries 33 [ [31].31Peel]. LobationLobation & Streng ininFlumenoglacies Flumenoglacies2015 [76]; Hipponicharionidae; developsdevelops aa singlesingle comarginalcomarginal Range: Cambrian lobelobe [[31].31]. Series 3. FlumenoglaciesGaleopsisGaleopsis Hinz-Schallreuter, Hinz-Schallreuter,is a hipponicharionid 1993 1993 [bradoriid 56[56];]; ?Beyrichonidae; ?Bey richonidae;from British Range: Range: Columbia LateLate Wuliuan.andWuliuan. North Greenland from CambrianGladioscutumGladioscutum Series 3 [31].Hinz-Schallreuter Lobation in Flumenoglacies & & Jones, Jones, 1994 1994 develops [77]; [77 ];Ca Cambriidae;mbriidae; a single comarginal Range: Range: Middle lobe Middle [31].Cambrian, Cambrian, Late LateDrumian.Galeopsis Drumian. Gladioscutum Hinz-Schallreuter,Gladioscutum is consideredis considered 1993 to[56]; be to ?Beya belaterichonidae; a surviving late surviving cambriidRange: cambriid Late taxon Wuliuan. taxon [5]. [5 ]. HanchiangellaGladioscutumHanchiangella Hinz-Schallreuter Huo et et al. al. 2002 2002 [4]; [ 4& ];Kunminge Jones, Kunmingellidae; 1994llidae; [77]; Range: Ca Range:mbriidae; early early Cambrian Range: Cambrian Middle AbadiellaAbadiella Cambrian, Biozone.Biozone. Late One OneDrumian.of the of theearliest Gladioscutum earliest bradoriids, bradoriids, is considered HanchiangellaHanchiangella to be minor a minor late (Figure surviving(Figure 14) 14 cambriidoccurs) occurs in intaxon the the AbadiellaAbadiella [5]. Biozone of SouthSouth ChinaChinaHanchiangella [[5].5]. Huo et al. 2002 [4]; Kunmingellidae; Range: early Cambrian Abadiella Biozone. One of the earliest bradoriids, Hanchiangella minor (Figure 14) occurs in the Abadiella Biozone of South China [5].

Figure 14. Hanchiangella minor. Anterior to left. Length of shield approximately 3.5 mm. Abbreviations: adn, anterodorsal node; amr, admarginal rim; pdn, posterodorsal node; vn, ventral node. Image Credit: MarkFigure McMenamin. 14. Hanchiangella minor. Anterior to left. Length of shield approximately 3.5 mm. Abbreviations: adn, anterodorsal node; amr, admarginal rim; pdn, posterodorsal node; vn, ventral Figurenode. Image14. Hanchiangella Credit: Mark McMenamin.minor. Anterior to left. Length of shield approximately 3.5 mm. Abbreviations: adn, anterodorsal node; amr, admarginal rim; pdn, posterodorsal node; vn, ventral

node. Image Credit: Mark McMenamin.

Geosciences 2020, 10, x FOR PEER 15 of 37 Geosciences 2020, 10, 119 15 of 37 Hanchungella Huo, 1956 [78]; Bradoriidae; Range: Stage 3, early. Hanchungella has a non-lobate shield [19].Hanchungella Huo, 1956 [78]; Bradoriidae; Range: Stage 3, early. Hanchungella has a non-lobate Haoiashield Shu, [19]. 1990 [70]; ?Haoiidae; Range: Middle to late Stage 3. Haoia cf. H. shaanxiensis from the MernmernaHaoia Formation,Shu, 1990 Flinders [70]; ?Haoiidae; Ranges, Range: South Middle Austra tolia late has Stage a coarse 3. Haoia ornamentcf. H. shaanxiensis of elongatefrom theridges with smallMernmerna pustules Formation, in the low Flinders spaces Ranges, between South ridges Australia [6]. The has genus a coarse is distinguished ornament of elongate by consisting ridges of “weaklywith postplete small pustules bradoriids in the lowwith spaces a V-shaped between anterodorsal ridges [6]. The sulcus genus and is distinguished multiple, ridge-like by consisting lobes” of [6]. Hipponicharion“weakly postplete Matthew, bradoriids with1886 a V-shaped[57]; Hipponicharionida anterodorsal sulcuse; and Range: multiple, Stage ridge-like 3 to lobes” Wuliuan. [6]. HipponicharionHipponicharion (Figures 15,Matthew, 16) was 1886 first [57described]; Hipponicharionidae; from Avalonia Range:by Matthew Stage in 31886 to Wuliuan.[57]. It is a characteristicHipponicharion genus(Figures of the Cambrian 15 and 16 )Series was first2–3 describedHanford Brook from Avalonia Formation by Matthewof New Brunswick in 1886 [57 ].[31]. It is a characteristic genus of the Cambrian Series 2–3 Hanford Brook Formation of New Brunswick [31]. Hipponicharion geyeri has punctae that open to the exterior [6]. The posterior lobe in Hipponicharion is Hipponicharion geyeri has punctae that open to the exterior [6]. The posterior lobe in Hipponicharion is close to the edge of the valve [31]. Hipponicharion is considered to be characteristic of shallow water close to the edge of the valve [31]. Hipponicharion is considered to be characteristic of shallow water deposits,deposits, and is and common is common to both to both east east and and particularly particularly west west Gondwana Gondwana [19], [19], while while also occurring in Laurentiain Laurentia and South and SouthChina China [31]. [31A ].growth A growth series series of of HipponicharionHipponicharion loculatumloculatum(Figure (Figure 15 )15) shows shows isometricisometric growth growth [43]. [ 43Hipponicharionids]. Hipponicharionids are are characterized characterized by by a clearclear marginal marginal rim, rim, a dorsala dorsal central central node, node,and posterior and posterior and anterior and anterior lobes lobes that thatare not are notconnected connected [24]. [24 Similar]. Similar to the to theBeyrichonidae, Beyrichonidae, they have athey deep have subtriangular a deep subtriangular shield. Hipponicharionid shield. Hipponicharionid genera genera are distinguished are distinguished by by“shield “shield shape, shape, size and ventralsize and extent ventral of extentthe anterior of the anterior and posterior and posterior lobes” lobes” [25] and [25] by and “a by straight “a straight dorsal dorsal margin, margin, a well- a definedwell-defined hinge-line, hinge-line, a narrow, a narrow, entire entire admarginal admarginal ridge ridge and and prominent prominent dorsoventrallydorsoventrally orientated orientated lobationlobation in which in which the anteriormost the anteriormost and and posteriormost posteriormost lobes lobes are are subparallelsubparallel to to the the adjacent adjacent... .valve . . valve outline”outline” [20]. [20].

Figure 15. Hipponicharion loculatum. Paired shields shown in butterfly position. Anterior to Figure 15. Hipponicharion loculatum. Paired shields shown in butterfly position. Anterior to left. Length left. Length of shield 1.5 mm. Abbreviations: a, anterodorsal cardinal marginal concavity; adn, of shieldanterodorsal 1.5 mm. Abbreviations: node; pdn, posterodorsal a, anterodorsal node. Image cardinal Credit: marginal Mark McMenamin. concavity; adn, anterodorsal node; pdn, posterodorsal node. Image Credit: Mark McMenamin.

Geosciences 2020, 10, x FOR PEER 16 of 37 GeosciencesGeosciences 20202020, ,1010, ,x 119 FOR PEER 1616 of of 37 37

Figure 16. Hipponicharion skovstedi. Paired shields shown in butterfly position. Anterior to left. Scale Figure 16. Hipponicharion skovstedi. Paired shields shown in butterfly position. Anterior to left. bar 200 microns. Abbreviations: adn, anterodorsal node; pdn, posterodorsal node. Image Credit: FigureScale bar 16. 200Hipponicharion microns. Abbreviations: skovstedi. Pairedadn ,shields anterodorsal shown node; in butterflypdn, posterodorsal position. Anterior node. Imageto left. Credit:Scale Mark McMenamin. barMark 200 McMenamin. microns. Abbreviations: adn, anterodorsal node; pdn, posterodorsal node. Image Credit: Mark McMenamin. Houlongdongella Li, 19751975 [[72];72]; Zhexiellidae;Zhexiellidae; Range:Range: Middle Stage 3.3. This This bradoriid bradoriid has a morphologicallyHoulongdongella simple Li, shield1975 [72]; and couldZhexiellidae; be confusedconfused Range: withwith MiddleFlemingopsisFlemingopsis Stage,, ZepaeraZepaera 3. This andand bradoriid QuetopsisQuetopsis has [[25].25 ].a morphologicallyIfersiktia Hinz-Schallreuter,Hinz-Schallreuter, simple shield and 19931 could993 [[74];74 be]; confused Bradoriidae;Bradoriidae; with Range:FlemingopsisRange: early, Zepaera Wuliuan.Wuliuan. and QuetopsisThis This bradoriid, [25]. IfersiktiaIfersiktia mipora Hinz-Schallreuter,, is from JbelJbel boubou Ifersikht,Ifersikht,1993 [74]; Anti-Atlas,Anti-Atlas, Bradoriidae; MoroccoMorocco Range: [[19,74].19 ,74early]. Wuliuan. This bradoriid, IfersiktiaIndiana mipora Matthew,, is from 19021902Jbel bou [[79];79]; Ifersikht, Bradoriidae;Bradoriidae; Anti-Atlas, Range:Range: Morocco Stage 3 to [19,74]. early Wuliuan. The valves of Indiana are smoothIndianasmooth and Matthew,and relatively relatively 1902 featureless, [79];featureless, Bradoriidae; although although Range: some some species Stage species 3 may to early showmay Wuliuan. fineshow punctae fine The punctae [valves7]. Once of[7]. assigned Indiana Once aretoassigned thesmooth family to andthe Indianidae familyrelatively Indianidae [ 7featureless,], it was [7], later italthough was transferred late rsome transferred to species the Bradoriidae to may the Bradoriidaeshow [25 ].fine Specimens punctae [25]. Specimens [7]. of Indiana Once of assignedlentiformisIndiana lentiformis to (Figurethe family (Figure17) Indianidae reaching 17) reaching up [7], to it 13.3up was to mm late13.3 inr mmtransferred length in length occur to occur inthe the Bradoriidae in Comley the Comley Series [25]. Series Specimens of Wales of Wales and of IndianaEnglandand England lentiformis [20]. [20].Indiana (Figure Indianaaff. I.17) aff. dermatoides reaching I. dermatoides upand toIndiana and 13.3 Indiana mmsp. in have sp.length beenhave occur reportedbeen in reported the from Comleythe from Franconian Series the Franconian of Wales Forest andofForest eastern England of eastern Bavaria, [20]. Bavaria, Indiana Germany Germanyaff. [I.19 dermatoides]. Indiana [19]. Indianais and characteristic Indianais characteristic sp. of have shallow of been shallow marine reported marine environments from environments the Franconian [19]. [19]. Forest of eastern Bavaria, Germany [19]. Indiana is characteristic of shallow marine environments [19].

Figure 17. Indiana lentiformis. Anterior to left. Length of shield 13.3 mm. Image Credit: Mark McMenamin. Figure 17. Indiana lentiformis. Anterior to left. Length of shield 13.3 mm. Image Credit: Mark FigureIndianitesMcMenamin. 17. IndianaUlrich &lentiformis Bassler,. Anterior 1931 [80 ];to Bradoriidae;left. Length ofIndianites shield 13.3 caenensis mm. Imagewas theCredit: first Mark bradoriid discoveredMcMenamin. in France, from the Saint-jean-de-la-Rivière Formation, Carteret, Normandy (Bigotina Biozone) [19]. The species may in fact be a simple svealutid [19].

Geosciences 2020, 10, x FOR PEER 17 of 37 Geosciences 2020, 10, x FOR PEER 17 of 37 Indianites Ulrich & Bassler, 1931 [80]; Bradoriidae; Indianites caenensis was the first bradoriid discoveredIndianites in France,Ulrich &from Bassler, the Saint-jean-de-1931 [80]; Bradoriidae;la-Rivière IndianitesFormation, caenensis Carteret, was Normandy the first bradoriid(Bigotina Geosciences 2020, 10, 119 17 of 37 Biozone)discovered [19]. in TheFrance, species from may the in Saint-jean-de-fact be a simplela-Rivière svealutid Formation, [19]. Carteret, Normandy (Bigotina Biozone)Indota [19]. Öpik, The 1968species [65]; may Bradoriidae; in fact be a simpleRange: svealutidStage 3 to[19]. early Wuliuan. Indota? sp. has been reportedIndotaIndota fromÖpik, Öpik, the 1968 Franconian1968 [65 [65];]; Bradoriidae; Bradoriidae; Forest of Range:eastern Range: Stage Bavaria, Stage 3 to Germany early3 to Wuliuan.early [19]. Wuliuan. Indota? sp.Indota has? beensp. has reported been fromreportedJiucunella the Franconianfrom Houthe Franconian & Forest Bergström, of easternForest 1991 of Bavaria, [81]; eastern ?Alu Germany Bavaria,tidae; Range: Germany [19]. Middle [19]. Stage 3. Jiucunella occurs in the WirrapowieJiucunellaJiucunella Limestone HouHou && Bergström,Bergström, in the M. etheridgei 19911991 [[81];81]; Zone, ?Alutidae;?Alu tidae;Flinders Range:Range: Ranges, MiddleMiddle Australia StageStage [28,82].3.3. JiucunellaJiucunella Jiucunella occursoccurs phaseloa inin thethe WirrapowieFigureWirrapowie 18 has LimestoneLimestone a valve outline inin thethe (tiltedM. M. etheridgeietheridgei forward)Zone, Zone, similar FlindersFlinders to that Ranges,Ranges, of Jixinlingella AustraliaAustralia daimonikoa [[28,82].28,82]. JiucunellaJiucunella, but has a phaseloaphaseloa largely FiguresmoothFigure 1818 valve hashas aasurface valve outline and lacks (tilted the forward)polygonal similarsimilar ornamentation. toto that of Jixinlingella daimonikoadaimonikoa,, butbut hashas aa largely smoothsmooth valvevalve surfacesurface andand lackslacks thethe polygonalpolygonal ornamentation.ornamentation.

Figure 18. Jiucunella phaseloa. Anterior to left. Scale bar 200 microns. Abbreviation: adn, Figure 18. Jiucunella phaseloa. Anterior to left. Scale bar 200 microns. Abbreviation: adn, anterodorsal anterodorsal node. Image Credit: Mark McMenamin. node.Figure Image 18. Jiucunella Credit: Markphaseloa McMenamin.. Anterior to left. Scale bar 200 microns. Abbreviation: adn, anterodorsal Jixinlingellanode. Image Li,Credit: 1975 Mark [72]; McMenamin. ?Alutidae; Range: Middle Stage 3. Jixinlingella occurs in the Wirrapowie LimestoneJixinlingella in the M.Li, etheridgei1975 [72];Zone, ?Alutidae; Flinders Range: Ranges, Middle Australia Stage [ 283. Jixinlingella,82]. Jixinlingella occurs daimonikoa in the Wirrapowieis covered byLimestone a coarseJixinlingella polygonalin the Li, M. 1975 ornamentetheridgei [72]; ?Alutidae; ofZone, ridges Flinders formingRange: MiddleRanges, a pattern Stage Australia of interlocked 3. Jixinlingella [28,82]. hexagons Jixinlingellaoccurs (giving in the daimonikoa Wirrapowie the valves is a surfacecoveredLimestone texture by ina coarse thatthe M. somewhat polygonal etheridgei resembles ornament Zone, Flinders the of surface ridges Ranges, textureforming Australia of a a pattern roasted [28,82]. of peanut interlocked Jixinlingella shell), andhexagons adaimonikoa two-pointed (giving is spinethecovered valves projects by a a surface coarse fromthe polygonaltexture posterior that ornament somewhat of the valve. of ridgesresembles The forming valve the ornamentation surface a pattern texture of interlocked is of comparable a roasted hexagons peanut to that (giving shell), of the ostracodandthe valvesa two-pointedCythereis a surface cretaria texturespine dorsocaudataprojects that somewhat fromfrom the resembles Late poster Cretaceousior the of surface the strata valve. texture of IsraelThe of valve a [83 roasted]. Shortornamentation peanut denticulate shell), is spinescomparableand a occurtwo-pointed to along that of the spine the ventral ostracod projects margin Cythereis from of thethe cretaria valveposter dorsocaudata iniorJixinlingella of the fromvalve. daimonikoa Late The Cretaceous valve(Figure ornamentation 19strata). The of ridgeIsrael is ornament[83].comparable Short is denticulate comparableto that of the spines to ostracod the ridgeoccur Cythereis ornamentalong the cretaria ofventral the dorsocaudata Eocene-Oligocene margin of from the valve Late Belgian Cretaceousin ostracodJixinlingella strataQuadracythere daimonikoa of Israel macropora(Figure[83]. Short 19).[ 71denticulate The]. This ridge genus ornament spines is sometimes occur is comparable along misspelled the toventral the “Jixinglingella” ridge margin ornament of the [ 2of ].valve the Eocene-Oligocene in Jixinlingella daimonikoa Belgian ostracod(Figure 19). Quadracythere The ridge ornament macropora is [71]. comparable This genus to th ise sometimesridge ornament misspelled of the Eocene-Oligocene“Jixinglingella” [2]. Belgian ostracod Quadracythere macropora [71]. This genus is sometimes misspelled “Jixinglingella” [2].

Figure 19. Jixinlingella daimonikoa. Anterior to left. Scale bar 200 microns. Abbreviation: dc, dorsal cusp. ImageFigure Credit:19. Jixinlingella Mark McMenamin. daimonikoa. Anterior to left. Scale bar 200 microns. Abbreviation: dc, dorsal cusp.Figure Image 19. Jixinlingella Credit: Mark daimonikoa McMenamin.. Anterior to left. Scale bar 200 microns. Abbreviation: dc, dorsal Kazakhstanotubuluscusp. Image Credit: MarkGridina, McMenamin. 1991 [84 ]; Duibianellidae; This genus, from the lower Cambrian of centralKazakhstanotubulus Kazakhstan [6], mayGridina, represent 1991 a[84]; bradoriid Duibianellidae; spine. Second-order This genus, spinesfrom the are lower present. Cambrian The short of curvedcentralKazakhstanotubulus spineKazakhstanSeletellus [6],can mayGridina, co-occur represent 1991 with [84];a bradoriidKazakhstanotubulus Duibianellidae; spine. Second-order Thisand genus, the two spinesfrom may the are represent lower present. Cambrian parts Theof short the of samecentral animal Kazakhstan [6]. [6], may represent a bradoriid spine. Second-order spines are present. The short Koksodus Missarzhevsky & Mambetov, 1981 [85]; Koksodus is a spiny possible bradoriid fragment from lower Cambrian strata of Malyi Karatau [6]. Geosciences 2020, 10, x FOR PEER 18 of 37

curved spine Seletellus can co-occur with Kazakhstanotubulus and the two may represent parts of the same animal [6]. Geosciences 2020, 10, 119 18 of 37 Koksodus Missarzhevsky & Mambetov, 1981 [85]; Koksodus is a spiny possible bradoriid fragment from lower Cambrian strata of Malyi Karatau [6]. KonicekionKonicekionŠnajdr, Šnajdr, 1975 1975 [86]; [86]; Hipponicharionidae; Hipponicharionidae; Range: Range: Stage Stage 3, early3, early to middle.to middle.Konicekion Konicekion snajdri , K. tixsnajdri, and ,Konicekion K. tix, and radionKonicekionall occurradion inallthe occur Jince in Formationthe Jince Formation (middle (middle Cambrian), Cambrian), Czech Czech Republic. Republic. However, considering taphonomic issues and the morphological variability common to However, considering taphonomic issues and the morphological variability common to bradoriids, bradoriids, the three species of Konicekion may in fact represent a single species [19]. Konicekion may Konicekion Konicekion the threebe synonymous species of with Albrunnicolamay in fact[19]. represent a single species [19]. may be synonymous with AlbrunnicolaKunmingella[19 ].Huo, 1956 [78]; Kunmingellidae; Range: Middle Stage 3 to earliest Stage 4. Due to Kunmingellaits occurrenceHuo, in the 1956 Chengjiang [78]; Kunmingellidae; Lagerstätte, Kunmingella Range: douvillei Middle is Stage the only 3 to bradoriid earliest Stage for which 4. Due the to its occurrencelimb morphology in the Chengjiang is known Lagerstätte, [3]. The Kunmingellaanterior of the douvillei two islobes the onlyin Kunmingella bradoriid for(Figure which 20) the is limb morphologyequidimensional is known and [3]. short The [31]. anterior Kunmingella of the two (along lobes with in KunmingellaKunyangella) was(Figure recovered 20) is equidimensionalas the basal- and shortmost [mandibulate31]. Kunmingella stem (alongin a phylogenetic with Kunyangella analysis) wasof the recovered Panarthropoda as the basal-most[87]. A specimen mandibulate of stemKunmingella in a phylogenetic douvillei analysis from the of Maotianshan the Panarthropoda Shale shows [87]. Awhat specimen are interpreted of Kunmingella as integumental douvillei from the Maotianshanhemolymph networks Shale shows [2]. what are interpreted as integumental hemolymph networks [2].

Figure 20. Kunmingella maotianshanensis. Anterior to left. Length of shield 4 mm. Abbreviations: a, anterodorsalFigure 20. cardinal Kunmingella marginal maotianshanensis concavity;. Anterioradn, anterodorsal to left. Length node; of shieldpdn, posterodorsal4 mm. Abbreviations: node. Imagea, Credit:anterodorsal Mark McMenamin. cardinal marginal concavity; adn, anterodorsal node; pdn, posterodorsal node. Image Credit: Mark McMenamin. Kunyangella Huo, 1965 [88]; Comptalutidae; Range: Middle Stage 3 to earliest Stage 4. KunyangellaKunyangella(along withHuo, Kunmingella1965 [88]; Comptalutidae;) was recovered Range: as theMiddle basal-most Stage 3 mandibulateto earliest Stage stem 4. in a phylogeneticKunyangella analysis (along of with the PanarthropodaKunmingella) was [87 recovered]. as the basal-most mandibulate stem in a LeperditaphylogeneticJones, analysis 1856 of [89 the]; ThisPanarthropoda British bradoriid, [87]. Leperdita solvensis, was the one of the first to be described,Leperdita and was Jones, called 1856 at [89]; the This time British an ostracod bradoriid, crustacean Leperdita solvensis [89]. The, was genus the one is of also the referredfirst to be to as described, and was called at the time an ostracod crustacean [89]. The genus is also referred to as Leperditia Rouault [90]. Note that Rouault [90] described a leperditicopid ostracod that was apparently Leperditia Rouault [90]. Note that Rouault [90] described a leperditicopid ostracod that was convergent on Cambro-Ordovician leperditid bradoriids. Nevertheless, Leperditia hicksi is reported apparently convergent on Cambro-Ordovician leperditid bradoriids. Nevertheless, Leperditia hicksi is fromreported the Middle from Cambrian the Middle ofCambrian South Wales of South [91 Wales] making [91] making it either it aeither bradoriid a bradoriid or the or oldestthe oldest known ostracod.known Walcott ostracod. [27 Walcott] illustrated [27] illu whatstrated he describedwhat he described as Leperditia as Leperditia dermatoides dermatoidesfrom from the Taconic the Taconic strata of Washingtonstrata of County, Washington New County, York. TheNew species York. The (greatest species length(greatest 6 mm)length is 6 notable mm) is notable for roughly for roughly ellipsoidal shape,ellipsoidal its finely shape, punctate its finely shield punctate surface shield (which surface led Walcott(which led [27 Walcott] to consider [27] to assigningconsider assigning the species the to a new genus),species to and a new a faintly genus), marked, and a faintly arched marked, hinge arched line. hinge line. LiangshanellaLiangshanellaHuo, Huo, 1956 1956 [78 [78];]; Svealutidae; Svealutidae; Range:Range: Stag Stagee 3 3to to early early Drumian, Drumian, with with question question to to Furongian,Furongian, late late Stage Stage 9. Liangshanella9. Liangshanella(Figure (Figure 2121)) consists of of “postplete “postplete bradoriid bradoriid valves valves from from the the Cambrian that display little or no lobation” [19]. The genus can be difficult to distinguish from Cambrian that display little or no lobation” [19]. The genus can be difficult to distinguish from Indiana, Indiana, Hanchungella, Ovaluta and Indota [19]. Liangshanella circumbolina is a relatively smooth-walled Hanchungella, Ovaluta and Indota [19]. Liangshanella circumbolina is a relatively smooth-walled species at species at first glance, but on closer inspection it bears surface pores with complex ornament (Figure first glance,22) consisting but on of closer a ring inspection divided into it bears a dozen surface wedg poreses and with a central complex pit [25]. ornament This feature (Figure is unknown22) consisting of a ring divided into a dozen wedges and a central pit [25]. This feature is unknown from any other bradoriid, but might be compared to openings for sensory setae as occur in modern ostracods [25], as for example in the modern ostracod Elofsonia baltica [92]. These remarkable structures are only 5 microns in diameter. Protruding tubular structures with “sealed ends” occur on valve interiors, and resemble similar structures (domal pads capping interior protrusions) in Euzepaera. Liangshanella aff. L. liangshanensis and Liangshanella sp. have been reported from the Jince Formation of the Czech Republic [19]. Liangshanella circumbolina (Figures 21 and 22) occurs below the oldest trilobites (Abadiella Geosciences 2020, 10, x FOR PEER 19 of 37 from any other bradoriid, but might be compared to openings for sensory setae as occur in modern ostracods [25], as for example in the modern ostracod Elofsonia baltica [92]. These remarkable structures are only 5 microns in diameter. Protruding tubular structures with “sealed ends” occur on valve interiors,Geosciences 2020and, 10 resemble, x FOR PEER similar structures (domal pads capping interior protrusions)19 of 37 in Euzepaera. Liangshanella aff. L. liangshanensis and Liangshanella sp. have been reported from the Jince Formationfrom of anythe otherCzech bradoriid, Republic but [19]. might Liangshanella be compared circumbolina to openings for (Figures sensory 21, setae 22) as occurs occur in below modern the oldest trilobitesostracods ( Abadiella[25], as forhuoi example Zone) inin thethe Ajaxmodern Limestone, ostracod FlindersElofsonia Ranges,baltica [92]. Australia, These remarkable and is thus structures are only 5 microns in diameter. Protruding tubular structures with “sealed ends” occur on the oldest known bradoriid (lower Cambrian, Series 2, Stage 3) from East Gondwana [25]. valve interiors, and resemble similar structures (domal pads capping interior protrusions) in GeosciencesEuzepaera2020, 10, 119. Liangshanella aff. L. liangshanensis and Liangshanella sp. have been reported from the Jince19 of 37 Formation of the Czech Republic [19]. Liangshanella circumbolina (Figures 21, 22) occurs below the oldest trilobites (Abadiella huoi Zone) in the Ajax Limestone, Flinders Ranges, Australia, and is thus huoi Zone)the inoldest the Ajaxknown Limestone, bradoriid (lower Flinders Cambrian, Ranges, Series Australia, 2, Stage and 3) from is thus East the Gondwana oldest known [25]. bradoriid (lower Cambrian, Series 2, Stage 3) from East Gondwana [25].

Figure 21. Liangshanella circumbolina. Anterior to left. Scale bar 500 microns. Abbreviation: amr, admarginalFigure 21. Liangshanellarim. Image Cr circumbolinaedit: Mark McMenamin.. Anterior to left. Scale bar 500 microns. Abbreviation: amr, admarginalFigure rim. 21. Image Liangshanella Credit: circumbolina Mark McMenamin.. Anterior to left. Scale bar 500 microns. Abbreviation: amr, admarginal rim. Image Credit: Mark McMenamin.

Figure 22. Liangshanella circumbolina. Detail of surface pore consisting of a ring divided into a dozen wedges with a central pit. Scale bar 5 microns. Image Credit: Mark McMenamin. Figure 22. Liangshanella circumbolina. Detail of surface pore consisting of a ring divided into a dozen wedgesManawarra withFigure Bettsa central22. Liangshanella et al. pit. 2017 Scale circumbolina [41 bar]; 5 Range: microns.. Detail early Image of Cambrian,surface Credit: pore Mark consistingDailyatia McMenamin. of odyssei a ring divided Zone. Manawarrainto a dozen jonesi is an Australianwedges bradoriid. with a central pit. Scale bar 5 microns. Image Credit: Mark McMenamin. ManawarraMatthoria Siveter Betts et &al. Williams, 2017 [41]; 1997Range: [20 early]; Cambriidae; Cambrian, Dailyatia Range: Lateodyssei Stage Zone. 3 Manawarra to early Stage jonesi 4. Manawarra Betts et al. 2017 [41]; Range: early Cambrian, Dailyatia odyssei Zone. Manawarra jonesi isMatthoria an Australianhas postplete bradoriid. valves with decided swing, and an anterodoral node that narrows towards the is an Australian bradoriid. Matthoria Siveter & Williams, 1997 [20]; Cambriidae; Range: Late Stage 3 to early Stage 4. cardinal cornerMatthoria [33]. ASiveter posterodorsal & Williams, node 1997 is lacking.[20]; Cambriidae; The Montagne Range: Noir Late (PardailhanStage 3 to early Formation) Stage 4. of MatthoriasouthernMatthoria Francehas postplete hashas producedpostplete valves valves ?withMatthoria withdecided decidedsp. swing, [19 ,33swing,]. and This and an genus ananterodoral anterodoral has obsolete node node lobation thatthat narrows [5]. towards towards the cardinalMeishucunellathe cardinal corner Jiang [33].corner A in [33]. posterodorsal Luo A et posterodorsal al. 1982 node [93 ];node is Hipponicharionidae; lacking. is lacking. The The Montagne Montagne Range: Noir Noir Stage (Pardailhan (Pardailhan 3, early. Formation) Formation) Lobation in ofMeishucunella southernof southern Francedevelops Francehas produced a singlehas produced comarginal ?Matthoria ?Matthoria lobesp. [19,33].sp. [31 [19,33].]. This This genus genus has has obsolete obsolete lobationlobation [5].[5]. MeishucunellaMelvillellaMeishucunellaWrona, Jiang 2009 in Jiang Luo [44 in]; et Luo Svealutidae; al. et1982 al. 1982[93]; Range: [93]; Hipponicharionidae; Hipponicharionidae; Late Stage 3 (with Range: Range: question). Stage Stage 3,3, early. Lobation Lobation in MeishucunellaMonasteriumin Meishucunella developsMelnikova develops a single in Melnikovaa single comarginal comarginal et al. lobe 1997 lobe [31]. [94 [31]. ]; Monasteriidae; Range: Late Wuliuan to late StageMelvillella 9. An anterodorsallyMelvillella Wrona, Wrona, 2009 spiny [44]; 2009 bradoriid Svealutidae; [44]; Svealutidae; with Range: an anterodorsalRange: Late Late Stage Stage sulcus 3 (with3 (with and question). question). reticulate ornamentation [5]. Monceretia Vannier, Williams, Álvaro, J.J., Vaizcaïno, D., Monceret, S., and Monceret, E., 2005 [33]; Cambriidae; Range: Late Stage 3. Postplete Monceretia has a posteroventral node but no other

nodes; a short spine projects from the posterior cardinal corner [33]. The Montagne Noir (Pardailhan Formation) of southern France has produced Monceretia erisylvia [19]. Mongolitubulus Missarzhevsky, 1977 [95]; Duibianellidae; Range: Stage 3. This taxon, often preserved as an isolated, ornamented curved spine, has been the subject of much debate, with Mongolitubulus having been classified as a protoconodont, a pseudoconodont, a hyolithelminthid worm tube, and the defensive spine of a lobopodian. Melnikova [96] proposed the correct interpretation, namely, that these curved spines (here called great spines) represented prominent (to say the least) ornamentation projecting from the central parts of bradoriid valves. This interpretation was eventually confirmed by the discovery of a complete valve with its impressive spine still attached [97]. A defensive Geosciences 2020, 10, x FOR PEER 20 of 37

Monasterium Melnikova in Melnikova et al. 1997 [94]; Monasteriidae; Range: Late Wuliuan to late Stage 9. An anterodorsally spiny bradoriid with an anterodorsal sulcus and reticulate ornamentation [5]. Monceretia Vannier, Williams, Álvaro, J.J., Vaizcaïno, D., Monceret, S., and Monceret, E., 2005 [33]; Cambriidae; Range: Late Stage 3. Postplete Monceretia has a posteroventral node but no other nodes; a short spine projects from the posterior cardinal corner [33]. The Montagne Noir (Pardailhan Formation) of southern France has produced Monceretia erisylvia [19]. Mongolitubulus Missarzhevsky, 1977 [95]; Duibianellidae; Range: Stage 3. This taxon, often preserved as an isolated, ornamented curved spine, has been the subject of much debate, with Mongolitubulus having been classified as a protoconodont, a pseudoconodont, a hyolithelminthid worm tube, and the defensive spine of a lobopodian. Melnikova [96] proposed the correct Geosciencesinterpretation,2020, 10, 119 namely, that these curved spines (here called great spines) represented prominent (to20 of 37 say the least) ornamentation projecting from the central parts of bradoriid valves. This interpretation was eventually confirmed by the discovery of a complete valve with its impressive spine still attached function[97]. was A defensive implied [function6]; however, was implied a hydrodynamic [6]; however, function a hydrodynamic of these spines function as stabilizers of these spines should as also be considered.stabilizers Consideringshould also be their considered. relatively Considering fragile nature, their relatively these spines fragile might nature, be comparable these spines inmight function to thebe spines comparable of planktonic in function foraminifera. to the spinesMongolitubulus of planktonic foraminifera. henrikseni has Mongolitubulus an array of bothhenrikseni large has and an small spines.arrayMongolitubulus of both large and anthelios small (Figurespines. Mongolitubulus 23) occurs in theanthelios Wirrapowie (Figure 23) Limestone occurs in the in theWirrapowieM. etheridgei Zone,Limestone Flinders Ranges,in the M. Australiaetheridgei Zone, [82]. FlindersMongolitubulus Ranges, Australiasp. occurs [82]. in Mongolitubulus the Wirrapowie sp. Limestoneoccurs in the in the Wirrapowie Limestone in the Flinders Ranges, Australia [82]. The prominent lateral spines on Flinders Ranges, Australia [82]. The prominent lateral spines on Mongolitubulus are reminiscent of the Mongolitubulus are reminiscent of the prominent valve-central spines of the Eocene-Oligocene Belgian prominent valve-central spines of the Eocene-Oligocene Belgian ostracod Cytheropteron gulincki [71]. ostracod Cytheropteron gulincki [71].

Figure 23. Mongolitubulus anthelios. Oblique side view, anterior to left. Scale bar 200 microns. Abbreviation:Figure 23.gs Mongolitubulus, great spine. Imageanthelios Credit:. Oblique Mark side McMenamin. view, anterior to left. Scale bar 200 microns. Abbreviation: gs, great spine. Image Credit: Mark McMenamin. Mononotella Ulrich and Bassler, 1931 [66]; Range: Late stage 4. Mononotella is a univalve bradoriid Mononotella Ulrich and Bassler, 1931 [66]; Range: Late stage 4. Mononotella is a univalve bradoriid that lacks lobation and a lateroadmarginal rim [5]. that lacks lobation and a lateroadmarginal rim [5]. Nanchengella Nanchengella acuta NanchengellaHuo, Huo, 1956 1956 [78 [78];]; Kunmingellidae; Kunmingellidae; Range:Range: Stage Stage 3, 3, early. early. Nanchengella acuta occursoccurs in in the Abadiellathe AbadiellaBiozone Biozone of South of South China China [5 [5].]. NavaranaNavaranaPeel, Peel, 2017 2017 [31 [31];]; Hipponicharionidae; Hipponicharionidae; Navarana pearylandica pearylandica (Figure(Figure 24) 24occurs) occurs in the in the OvatoryctocaraOvatoryctocara granuata granuataassemblage assemblage of of the the Henson Henson GletscherGletscher Formation, Formation, at ata stratigraphic a stratigraphic position position at at the topthe of top Cambrian of Cambrian Series Series 2 [ 312 [31].]. Due Due to to its its prominent prominent lobes lobes (two (two each each on on the the lateral lateral sides sides of each of each valve),valve),Navarana Navaranais placed is placed with with the the hipponicharionids. hipponicharionids. The The posterior posterior lobe lobe in inNavaranaNavarana is closeis close to the to the centercenter of the of valvethe valve [31]. [31]. The The lobes lobes are are ornamented ornamented withwith prominent tubercle tubercless [31]. [31 Lobe]. Lobe separation separation Geosciencesdistinguishesdistinguishes 2020, 10Navarana, x FOR Navarana PEERfrom from other other genera. genera. 21 of 37

Figure 24. Navarana pearylandica. Anterior to left. Scale bar 100 microns. Abbreviations: adn, Figureanterodorsal 24. Navarana node; amr pearylandica, admarginal. Anterior rim; pdn to, posterodorsal left. Scale bar node. 100 Image microns. Credit: Abbreviations: Mark McMenamin. adn, anterodorsal node; amr, admarginal rim; pdn, posterodorsal node. Image Credit: Mark McMenamin. Neoduibianella Shu, 1990 [70]; Duibianellidae; Range: Middle Stage 3; with question to earlyNeoduibianella Drumian. Shu, 1990 [70]; Duibianellidae; Range: Middle Stage 3; with question to early Drumian.Neokunmingella Zhang, 1974 [98]; Hipponicharionidae; Range: Middle Stage 3 to Wuliuan; withNeokunmingella question to Tremadoc Zhang, 1974 (Ordovician). [98]; Hipponicharionidae; Lobation in Neokunmingella Range: Middle(Figure Stage 25 3) to develops Wuliuan; a singlewith question to Tremadoc (Ordovician). Lobation in Neokunmingella (Figure 25) develops a single comarginal lobe [31]. Neokunmingella moroensis occurs in the Wirrapowie Limestone in the Flinders Ranges, Australia [28,82]. This genus is known for sometimes showing “confluent anterior and posterior lobes” [25]. Each shield has a distinct posterior spine.

Figure 25. Neokunmingella moroensis. Anterior to left. Scale bar 200 microns. Abbreviations: a, anterodorsal cardinal marginal concavity; adn, anterodorsal node; cr, connecting ridge; pdn, posterodorsal node. Image Credit: Mark McMenamin.

Nicolarites Vasilieva, 1994 [99]; Duibianellidae; This genus, known from fragmentary remains of Yakutia (Nicolarites spasskyi) and possibly North Greenland [6], consists of hollow tubes, often paired with nodes, that may be the remains of (possibly toxic) bradoriid spines as in Spinospitella. Oepikaluta Jones & McKenzie, 1980 [23]; Comptalutidae; Range: late Drumian. Jones and McKenzie [23] considered Oepikaluta to be a phosphatocopid, but the genus is considered here to be a bradoriid. Onagrocharion Topper et al. 2007 [100]; Hipponicharionidae; Range: Late Stage 3. The type species of the genus is Onagrocharion tuberosus. Ornamented tube form A; This form from the lower Cambrian of Australia [6] may represent a bradoriid spine. Second-order spines are present. Ovaluta Zhang, 1987 [101]; Bradoriidae; Ovaluta has a non-lobate shield [19].

Geosciences 2020, 10, x FOR PEER 21 of 37

Figure 24. Navarana pearylandica. Anterior to left. Scale bar 100 microns. Abbreviations: adn, anterodorsal node; amr, admarginal rim; pdn, posterodorsal node. Image Credit: Mark McMenamin.

Neoduibianella Shu, 1990 [70]; Duibianellidae; Range: Middle Stage 3; with question to early GeosciencesDrumian.2020, 10 , 119 21 of 37 Neokunmingella Zhang, 1974 [98]; Hipponicharionidae; Range: Middle Stage 3 to Wuliuan; with question to Tremadoc (Ordovician). Lobation in Neokunmingella (Figure 25) develops a single comarginalcomarginal lobe lobe [31]. [31].Neokunmingella Neokunmingella moroensis moroensis occursoccurs in the the Wirrapowie Wirrapowie Limestone Limestone in the in theFlinders Flinders Ranges,Ranges, Australia Australia [28 ,[28,82].82]. This This genus genus isis knownknown forfor sometimes showing showing “confluent “confluent anterior anterior and and posteriorposterior lobes” lobes” [25]. [25]. Each Each shield shield has has a distincta distinct posterior posterior spine.

Figure 25. Neokunmingella moroensis. Anterior to left. Scale bar 200 microns. Abbreviations:

a, anterodorsalFigure 25. Neokunmingella cardinal marginal moroensis concavity;. Anterioradn to, left. anterodorsal Scale bar node;200 microns.cr, connecting Abbreviations: ridge; a, pdn, posterodorsalanterodorsal node. cardinal Image marginal Credit: Markconcavity; McMenamin. adn, anterodorsal node; cr, connecting ridge; pdn, posterodorsal node. Image Credit: Mark McMenamin. Nicolarites Vasilieva, 1994 [99]; Duibianellidae; This genus, known from fragmentary remains of Yakutia (NicolaritesNicolarites Vasilieva, spasskyi) and1994 possibly[99]; Duibianellidae; North Greenland This genus, [6], known consists from of hollowfragmentary tubes, remains often pairedof with nodes,Yakutia that (Nicolarites may be spasskyi the remains) and possibly of (possibly North toxic)Greenland bradoriid [6], consists spines of ashollow in Spinospitella tubes, often. paired Oepikalutawith nodes,Jones that may & be McKenzie, the remains 1980 of (possibly [23]; Comptalutidae; toxic) bradoriid spines Range: as in late Spinospitella Drumian.. Jones and McKenzieOepikaluta [23] considered Jones &Oepikaluta McKenzie,to 1980 be a [23]; phosphatocopid, Comptalutidae; but Range: the genus late Drumian. is considered Jones here and to be a bradoriid.McKenzie [23] considered Oepikaluta to be a phosphatocopid, but the genus is considered here to be Onagrochariona bradoriid. Topper et al. 2007 [100]; Hipponicharionidae; Range: Late Stage 3. The type species Onagrocharion Topper et al. 2007 [100]; Hipponicharionidae; Range: Late Stage 3. The type of the genus is Onagrocharion tuberosus. species of the genus is Onagrocharion tuberosus. Ornamented tube form A; This form from the lower Cambrian of Australia [6] may represent a Geosciences 2020Ornamented, 10, x FOR PEER tube form A; This form from the lower Cambrian of Australia [6] may represent22 a of 37 bradoriidbradoriid spine. spine. Second-order Second-order spines spines are are present. present. Ovaluta Zhang, 1987 [101]; Bradoriidae; Ovaluta has a non-lobate shield [19]. ParacambriaOvaluta Huo Zhang, & Shu,1987 [101];1985 [53];Bradoriidae; Cambriidae; Ovaluta Range: has a non-lobate Cambrian. shield [19]. Paracambria Huo & Shu, 1985 [53]; Cambriidae; Range: Cambrian. Parahoulongdonella Shu, 1990 [70]; Beyrichonidae; Range: Stage 3, early to middle. Parahoulongdonella Shu, 1990 [70]; Beyrichonidae; Range: Stage 3, early to middle. Parahoulongdonella bashanensis (Figure 26) occurs in the Wirrapowie Limestone in the M. etheridgei Parahoulongdonella bashanensis (Figure 26) occurs in the Wirrapowie Limestone in the M. etheridgei Zone Zone and the D. odyssei Zone, Flinders Ranges, Australia [82]. It is a relatively smooth-surfaced and the D. odyssei Zone, Flinders Ranges, Australia [82]. It is a relatively smooth-surfaced bradoriid bradoriid lacking nodes and with a relatively wide marginal rim. lacking nodes and with a relatively wide marginal rim.

Figure 26. Parahoulongdonella bashanensis. Anterior to left. Scale bar 200 microns. Abbreviations: adn, Figureanterodorsal 26. Parahoulongdonella node; amr, admarginal bashanensis rim.. Anterior Image Credit: to left. Mark Scale McMenamin. bar 200 microns. Abbreviations: adn, anterodorsal node; amr, admarginal rim. Image Credit: Mark McMenamin.

Pejonesia Hinz, 1992 [102]; family unknown [5]; Range: Late Wuliuan. Considered to be a phosphatocopid by Jones and Kruse [58], Pejonesia is considered here to be a bradoriid. Petrianna Siveter et al. 1996 [103]; Cambriidae; Range: Late Stage 3. At 17 mm long, Petrianna is the largest known bradoriid [2]. Perianna fulmenata is a large bradoriid from Greenland that is comparable to certain forms from China [31]. The anastomosing ridges on the shield surface [33,103] are likely reflections of the integumental hemolymph networks [2]. Phasoia Hinz-Schallreuter, 1993 [56]; Comptalutidae; Range: Stage 3 to Wuliuan. A sharp continuous ridge forms the lobation in this genus [58]. The surface ornamentation of Phasoia armini consists of 10-micron pores with polygonal boundaries [58]. I propose here that the round structures in the interior of most of these polygonal spaces reflect the presence of cell nuclei, hence the reticulate network represents the sheet of cells that was responsible for biomineralization. Preaechmina Shu, 1990 [70]; A spiny bradoriid with a single, central spine that is near the dorsal margin [6]. Pseudobeyrichona Cui in Shu, 1990 [70]; Hipponicharionidae; Range: Middle Stage 3. Pseudobeyrichona monile (Figure 27) from the Tannenknock Formation in Germany has a relatively smooth, lopsided (postplete) carapace, with distinct denticles ornamenting the marginal rim like a necklace, hence the name after Latin monile, necklace [19]. This genus may be synonymous with Beyrichona [6]; also assigned to Neokunmingella [6]. Pseudobeyrichona has also been reported from South China [19].

Geosciences 2020, 10, 119 22 of 37

Pejonesia Hinz, 1992 [102]; family unknown [5]; Range: Late Wuliuan. Considered to be a phosphatocopid by Jones and Kruse [58], Pejonesia is considered here to be a bradoriid. Petrianna Siveter et al. 1996 [103]; Cambriidae; Range: Late Stage 3. At 17 mm long, Petrianna is the largest known bradoriid [2]. Perianna fulmenata is a large bradoriid from Greenland that is comparable to certain forms from China [31]. The anastomosing ridges on the shield surface [33,103] are likely reflections of the integumental hemolymph networks [2]. Phasoia Hinz-Schallreuter, 1993 [56]; Comptalutidae; Range: Stage 3 to Wuliuan. A sharp continuous ridge forms the lobation in this genus [58]. The surface ornamentation of Phasoia armini consists of 10-micron pores with polygonal boundaries [58]. I propose here that the round structures in the interior of most of these polygonal spaces reflect the presence of cell nuclei, hence the reticulate network represents the sheet of cells that was responsible for biomineralization. Preaechmina Shu, 1990 [70]; A spiny bradoriid with a single, central spine that is near the dorsal margin [6]. Pseudobeyrichona Cui in Shu, 1990 [70]; Hipponicharionidae; Range: Middle Stage 3. Pseudobeyrichona monile (Figure 27) from the Tannenknock Formation in Germany has a relatively smooth, lopsided (postplete) carapace, with distinct denticles ornamenting the marginal rim like a necklace, hence the name after Latin monile, necklace [19]. This genus may be synonymous with GeosciencesBeyrichona 2020,[ 610];, alsox FOR assigned PEER to Neokunmingella [6]. Pseudobeyrichona has also been reported from South23 of 37 China [19].

Figure 27. Pseudobeyrichona monile. Anterior to left. Length of shield 2 mm. Image Credit: Mark McMenamin. Figure 27. Pseudobeyrichona monile. Anterior to left. Length of shield 2 mm. Image Credit: Mark McMenamin.Quadricona Topper, Skovsted, Brock & Paterson, 2011 [25]; Hipponicharionidae; Quadricona is a bradoriid with a very wide marginal rim and two obtusely pointed, circular nodes on each valve, withQuadricona the nodes Topper, in dorsoanterior Skovsted, and Brock dorsoposterior & Paterson, positions, 2011 [25]; respectively. Hipponicharionidae; Rumply ornamentation Quadricona is a bradoriidoccurs onwith the ventrala very partwide of marginal each valve. rim Conjoined and two valves obtusely viewed pointed, in a dorsal circular view of nodes the shield on (alongeach valve, withthe the hinge) nodes show in dorsoanterior that the nodes projectand dorsoposterior almost perpendicular positions, to the respectively. valve surface. Rumply The subamplete ornamentation occursQuadricona on the madonnaeventral part(Figures of each 28 andvalve. 29) Conjoined occurs in the va Wirrapowielves viewed Limestone in a dorsal in view the Flinders of the shield Ranges, (along theAustralia hinge) show [82]. that Each the obtusely nodes pointed project node almost in Quadricona perpendicular madonnae to theresembles valve surface. the tapered The process subamplete Quadricona(one per valve)madonnae of the (Figures Late Permian 28, 29) myodocopid occurs in ostracod the WirrapowieCypridinelliforma Limestone rex [104 in]. Thethe anteriorFlinders and Ranges, posterior lobes extend further ventrally in the Hipponicharionidae than in the Beyrichonidae [25]. Australia [82]. Each obtusely pointed node in Quadricona madonnae resembles the tapered process (one per valve) of the Late Permian myodocopid ostracod Cypridinelliforma rex [104]. The anterior and posterior lobes extend further ventrally in the Hipponicharionidae than in the Beyrichonidae [25].

Figure 28. Quadricona madonnae. Paired shields shown in butterfly position. Anterior to left. Scale bar 200 microns. Abbreviations: a, anterodorsal cardinal marginal concavity; adn, anterodorsal node; pdn, posterodorsal node. Image Credit: Mark McMenamin.

Geosciences 2020, 10, x FOR PEER 23 of 37

Figure 27. Pseudobeyrichona monile. Anterior to left. Length of shield 2 mm. Image Credit: Mark McMenamin.

Quadricona Topper, Skovsted, Brock & Paterson, 2011 [25]; Hipponicharionidae; Quadricona is a bradoriid with a very wide marginal rim and two obtusely pointed, circular nodes on each valve, with the nodes in dorsoanterior and dorsoposterior positions, respectively. Rumply ornamentation occurs on the ventral part of each valve. Conjoined valves viewed in a dorsal view of the shield (along the hinge) show that the nodes project almost perpendicular to the valve surface. The subamplete Quadricona madonnae (Figures 28, 29) occurs in the Wirrapowie Limestone in the Flinders Ranges, Australia [82]. Each obtusely pointed node in Quadricona madonnae resembles the tapered process (one Geosciencesper valve)2020 of, 10 the, 119 Late Permian myodocopid ostracod Cypridinelliforma rex [104]. The anterior23 of 37 and posterior lobes extend further ventrally in the Hipponicharionidae than in the Beyrichonidae [25].

Figure 28. Quadricona madonnae. Paired shields shown in butterfly position. Anterior to left. Scale bar Figure 28. Quadricona madonnae. Paired shields shown in butterfly position. Anterior to left. Scale bar Geosciences 2020200, microns. 10, x FOR Abbreviations: PEER a, anterodorsal cardinal marginal concavity; adn, anterodorsal node; pdn, 24 of 37 200 microns.posterodorsal Abbreviations: node. Image Credit:a, anterodorsal Mark McMenamin. cardinal marginal concavity; adn, anterodorsal node; pdn, posterodorsal node. Image Credit: Mark McMenamin.

Figure 29. Quadricona madonnae. Dorsal view of conjoined shields; anterior to left. Scale bar 500 microns. Abbreviations: adn, anterodorsal node; pdn, posterodorsal node. Image Credit: Mark McMenamin. Figure 29. Quadricona madonnae. Dorsal view of conjoined shields; anterior to left. Scale bar 500 microns.Quetopsis Abbreviations:Hinz-Schallreuter, adn, anterodorsal 1999 [105 ];node; Comptalutidae; pdn, posterodorsal Range: Late node. Wuliuan. Image ThisCredit: bradoriid Mark Houlongdongella Zepaera McMenamin.has a morphologically simple shield and could be confused with , and Flemingopsis [25]. QuetopsisRetaluta Hinz-Schallreuter,Zhang, 2007 [106]; 1999 Comptalutidae [105]; Comptalutidae; (Zhexiellidae); Range: Range: Late Middle Wuliuan. Stage 3.This bradoriid has Salanacus Grigorieva in Voronin et al. 1982 [107]; Salanacus is a spiny possible bradoriid fragment a morphologically simple shield and could be confused with Houlongdongella, Zepaera and (convex plates with smooth spines) from lower Cambrian strata from Mongolia and China [6]. Flemingopsis [25]. Sanlangella Liu et al. 2008 [108]; Comptalutidae; Range: early Cambrian. Sanlangella xixiangensis Retalutaoccurs in Zhang, the Yanwangbian 2007 [106]; Formation Comptalutidae of southern (Zhexiellidae); Shaanxi Province, Range: central Middle China [Stage108]. Sanlangella3. has Salanacuspostplete shieldsGrigorieva with in alarge Voronin mid-shield et al. 1982 node [107]; thatelongates Salanacus into is aa spiny pointed possible spine. bradoriid Shield ornament fragment (convexconsists plates of with reticulated smooth dimple-like spines) from impressions, lower Cambrian plus “a strata single from ventrally Mongolia elongate and China anterodorsal [6]. Sanlangellanode” [108]. Liu et al. 2008 [108]; Comptalutidae; Range: early Cambrian. Sanlangella xixiangensis occurs in the Yanwangbian Formation of southern Shaanxi Province, central China [108]. Sanlangella has postplete shields with a large mid-shield node that elongates into a pointed spine. Shield ornament consists of reticulated dimple-like impressions, plus “a single ventrally elongate anterodorsal node” [108]. Seletellus; See Kazakhstanotubulus. Sellula Wiman, 1902 [109]; Hipponicharionidae; Range: Late Stage 3 to early-late Stage 4 (with question). Septadella Stubblefield, 1933 [110]; Hipponicharionidae; Range: Guzhangian to Ordovician (early Tremadoc). Each valve of Septadella has seven elongate lobes [31]. The shields in Septadella bear a resemblance to, but are larger than, tetradellid ostracods, also from the Ordovician [5]. Shangsiella Li, 1975 [72]; Cambriidae; Range: Late early to Middle part of Stage 3. Shangsiella has a connected anterodorsal node, anterodorsal ridge, connecting ridge and posteroventral node, but its posterodorsal node is separate [33]. Shangsiella has been considered a synonym of Chuanbeiella, Paracambria and Antihipponicharion. Sinskolutella Melnikova, 1998 [111]; Alutidae; Range: Botomian Stage. In the Siberian Sinsk biota, Sinskolutella occurs in the Bergeroniellus gurarii Zone [8,112]. Sinskolutella cuspidata occurs in the Wirrapowie Limestone in the Flinders Ranges, Australia [28,82]. It has a relatively featureless shield, but does have a short spine on the carapace margin and an inclined aspect similar to that of Jixinlingella and Jiucunella. Spinaluta Zhang, 2007 [106]; Comptalutidae (Zhexiellidae); Range: Middle part of Stage 3. Spinella Zhang, 2007 [106]; Duibianellidae; Range: Middle part of Stage 3. Spinella unialata is considered synonymous with Mongolitubulus unispinoa [25]. Spinospitella Skovsted, Brock & Paterson 2006 [6]; Duibianellidae; Range: Stages 3 and 4. Spinospitella coronata is known from mostly fragmentary remains from the Mernmerna Formation, Bunkers Range, South Australia, Cambrian Stage 4 [6] in a stratigraphic section that also yields the trilobite Pararaia bunyerooensis plus five other species of trilobites. Ornamented spines and carapace fragments attributed to Spinospitella coronata occur in the Wirrapowie Limestone in the Flinders Ranges, Australia [82]. Complete adult specimens tend to be slightly crumpled, but the juveniles occur intact. The entire outer surface of the valve of Spinospitella is covered with fine ornamentation consisting of a reticulate pattern that may associate with tiny nodes. Like Mongolitubulus, Spinospitella

Geosciences 2020, 10, 119 24 of 37

Seletellus; See Kazakhstanotubulus. Sellula Wiman, 1902 [109]; Hipponicharionidae; Range: Late Stage 3 to early-late Stage 4 (with question). Septadella Stubblefield, 1933 [110]; Hipponicharionidae; Range: Guzhangian to Ordovician (early Tremadoc). Each valve of Septadella has seven elongate lobes [31]. The shields in Septadella bear a resemblance to, but are larger than, tetradellid ostracods, also from the Ordovician [5]. Shangsiella Li, 1975 [72]; Cambriidae; Range: Late early to Middle part of Stage 3. Shangsiella has a connected anterodorsal node, anterodorsal ridge, connecting ridge and posteroventral node, but its posterodorsal node is separate [33]. Shangsiella has been considered a synonym of Chuanbeiella, Paracambria and Antihipponicharion. Sinskolutella Melnikova, 1998 [111]; Alutidae; Range: Botomian Stage. In the Siberian Sinsk biota, Sinskolutella occurs in the Bergeroniellus gurarii Zone [8,112]. Sinskolutella cuspidata occurs in the Wirrapowie Limestone in the Flinders Ranges, Australia [28,82]. It has a relatively featureless shield, but does have a short spine on the carapace margin and an inclined aspect similar to that of Jixinlingella and Jiucunella. Spinaluta Zhang, 2007 [106]; Comptalutidae (Zhexiellidae); Range: Middle part of Stage 3. Spinella Zhang, 2007 [106]; Duibianellidae; Range: Middle part of Stage 3. Spinella unialata is considered synonymous with Mongolitubulus unispinoa [25]. Spinospitella Skovsted, Brock & Paterson 2006 [6]; Duibianellidae; Range: Stages 3 and 4. Spinospitella coronata is known from mostly fragmentary remains from the Mernmerna Formation, Bunkers Range, South Australia, Cambrian Stage 4 [6] in a stratigraphic section that also yields the trilobite Pararaia bunyerooensis plus five other species of trilobites. Ornamented spines and carapace fragments attributed to Spinospitella coronata occur in the Wirrapowie Limestone in the Flinders Ranges, Australia [82]. Complete adult specimens tend to be slightly crumpled, but the juveniles occur intact. The entire outer surface of the valve of Spinospitella is covered with fine ornamentation consisting of a reticulate pattern that may associate with tiny nodes. Like Mongolitubulus, Spinospitella carried ornamented spines, but in addition it has second- and third- order spines that cover the entire bivalve carapace in adult specimens. Second order spines in adults have a “crown of scales” [6] that resemble the scales that cover the large spines of Mongolitubulus henrikseni. The resulting primary spines are thus heavily ornamented, giving them a “Christmas Tree” look. As the abundant smaller second-order spines appear to be hollow, I propose here that they represent a defensive array of toxic spines comparable to those of the modern lion fish (Pterois volitans) or of caterpillars with toxic spines (such as the hag caterpillar Phobetron pithecium) that are used for defense against parasitoid wasps and other predators. Spinospitella coronata, with its first order and second order projections, has striking similarity to the Late Permian myodocopid ostracod from Greece Siveterella flex [104]. Sunella Melnikova et al. 1997 [96]; Range: Late Stage 3 to early Stage 4 (with question). Sunella occurs in the east Trans-Baikal region [96]. Tagra Hinz-Schallreuter, 1993 [55]; Beyrichonidae; Range: Early Wuliuan. Tagra koppkai is placed with question in the Beyrichonidae [19]. The species occurs in the central Anti-Atlas of Morocco (Tagragra Syncline), in the Ornamentaspis frequens Biozone [19]. Tscholponaella Melnikova in Melnikova et al. 1997 [94]; Range: Late Stage 3 (parvulus Biozone). Tscholponaella orientalis occurs in the Beshtash Formation of central Kazakhstan [5]. Tsunyiella Melnikova in Melnikova et al. 1997 [94]; Svealutidae; Range: Middle Stage 3 to early Stage 4. Tsunyiella is a round-oval bradoriid with a wide, smoothly rounded marginal rim. Tsunyiella gridinae from the Atdabanian of Kazakhstan shows what are interpreted as integumental hemolymph networks [2]. Geosciences 2020, 10, 119 25 of 37

Tubuterium Melnikova, 2000 [96]; Range: Late Stage 3 to middle Guzhangian. A spiny bradoriid. This Middle Cambrian genus is known from Siberia [96], and associated spines resembling Rushtonites may be broken-off parts of the Tubuterium valves. A reconstruction of Tubuterium ivantsovi is notable for portrayal of a bizarre anterodorsal recurved spine [6]. Undetermined svealutid; Svealutidae; An undetermined svealutid occurs in the Franconian Forest of eastern Bavaria, Germany [19]. Unnamed Indiana-like bradoriid; Bradoriidae; An unnamed Indiana-like bradoriid occurs in the Numayri Member of the Burj Formation, Dead Sea, Jordan (Kingaspis campbelli Biozone) [19]. Usatia Hinz-Schallreuter, 1993 [56]; family uncertain; Range: Late Wuliuan. Ushkarella Koneva, 1978 [113]; Hippocharionidae; Range: Late Stage 3 to early Stage 4 (with question). Ushkarella is from the Botomian of Kazakhstan. Evolutionarily convergent on palaeocopid ostracods, the genus was once placed in the Haoiidae [70] but is now placed in the Hippocharionidae [58]. Possibly a dimorphic taxon [58]. Uskutchiella Melnikova in Melnikova et al. 1997 [94]; Range: Late Pabian to early Stage 9. Uskutchiella sulcata occurs in the Tandoshka Formation of Gorny Altay [5]. Vojbokalina Melnikova in Khazanovich et al. 1984 [114]; Range: Late Drumian to early Guzhangian (with question). Earlier thought to have ostracod affinities [5], this tiny bradoriid is now thought to be convergent with ostracod ‘body plan 2’ [2]. Walcottella Ulrich & Bassler, 1931 [66]; Bradoriidae; Range: Wuliuan; late Stage 3 and Stage 4 (with question) and Drumian to Guzhangian (with question). Walcottella is known for its large anteromedian node and punctate valve [7]. Reticulated striae may occur in a concentric pattern around the anterocentral node [68]. Walcottella? aff. apicalis; Bradoriidae; A Walcottella-like bradoriid has been reported from lower Cambrian strata of Sweden [69]. The valve ornamentation is similar to that of the ostracod Anticythereis (?) bopaensis from the Paleocene of Nigeria [83]. Wimanicharion Hinz-Schallreuter, 1993 [56]; Hipponicharionidae; Range: Late Stage 4 to mid-Guzhangian. This genus is known for its “confluent anterior and posterior lobes” [25]. Lobation in Wimanicharion develops a single comarginal lobe [31]. Wimanicharion aff. W. matthewi has been reported from the Valdemiedes Formation (Ornamentaspis frequens Biozone) in northern Spain [19]. Wutingella Zhang, 1974 [98]; Comptalutidae; Range: Late early to Middle part of Stage 3. Wutingella binodosa occurs in the Abadiella to Eoredlichia-Wutingaspis Biozones of South China [5]. Yakutingella Melnikova, 1998 [111]; Kunmingellidae; Range: Botomian Stage. In the Siberian Sinsk biota [8], Yakutingella occurs in the Bergeroniellus gurarii Zone [112]. Yaoyingella Zhang, 1974 [98]; Zhexiellidae; This genus is thought to be a juvenile form of Comptaluta [21]. Yucola Zhang, 2007 [106]; Range: middle part of early Stage 4. Zepaera Fleming, 1973 [115]; Comptalutidae; Range: Stage 3 to Drumian. Zepaera has a wide anterodorsal margin and may develop a finely reticulate surface ornamentation. Anterior lobes form a distinctive omega-shape, but only in juveniles. The omega ridge fades in the adults [25]. The fossils tend to be slightly crumpled, suggesting that the valves were flexible in life. The genus is a “comptalutid bradoriid with distinctive lobes forming W-shaped ridges in the anterior half of juvenile valves. However, in larger growth stages the lobes are effaced ... and eventually disappear” [6]. The postplete comptalutid Zepaera jagoi (Figure 30; Ajax Limestone, Mount Scott Range, Australia) has fine teeth along its margin [25]. Early instars of Zepaera rete may be preplete [23,73]. Zepaera bandeli occurs in Australia, T. gibbus Biozone [5]. Geosciences 2020, 10, x FOR PEER 26 of 37

Yakutingella Melnikova, 1998 [111]; Kunmingellidae; Range: Botomian Stage. In the Siberian Sinsk biota [8], Yakutingella occurs in the Bergeroniellus gurarii Zone [112]. Yaoyingella Zhang, 1974 [98]; Zhexiellidae; This genus is thought to be a juvenile form of Comptaluta [21]. Yucola Zhang, 2007 [106]; Range: middle part of early Stage 4. Zepaera Fleming, 1973 [115]; Comptalutidae; Range: Stage 3 to Drumian. Zepaera has a wide anterodorsal margin and may develop a finely reticulate surface ornamentation. Anterior lobes form a distinctive omega-shape, but only in juveniles. The omega ridge fades in the adults [25]. The fossils tend to be slightly crumpled, suggesting that the valves were flexible in life. The genus is a “comptalutid bradoriid with distinctive lobes forming W-shaped ridges in the anterior half of juvenile valves. However, in larger growth stages the lobes are effaced . . . and eventually disappear” [6]. The postplete comptalutid Zepaera jagoi (Figure 30; Ajax Limestone, Mount Scott Range, Australia) Geoscienceshas fine teeth2020, 10along, 119 its margin [25]. Early instars of Zepaera rete may be preplete [23,73]. Zepaera bandeli26 of 37 occurs in Australia, T. gibbus Biozone [5].

Figure 30. Zepaera jagoi. Anterior to left. Scale bar 200 microns. Image Credit: Mark McMenamin. Figure 30. Zepaera jagoi. Anterior to left. Scale bar 200 microns. Image Credit: Mark McMenamin. Zhexiella Shu, 1990 [70]; Zhexiellidae; Range: Cambrian. A centrodorsal node occurs in Zhexiella, and theZhexiella genus Shu, lacks 1990 a well-developed [70]; Zhexiellidae; rim [Range:6]. Cambrian. A centrodorsal node occurs in Zhexiella, and the genus lacks a well-developed rim [6]. 7. Bradoriid Paleobiogeography 7. Bradoriid Paleobiogeography Bradoriids formed a cosmopolitan part of the Cambrian microbenthos, and may have originated in theBradoriids South China formed region a cosmopolitan [5]. Bradoriids part of have the Cambrian been utilized microbenthos, to define twoand may paleobiogeographic have originated provinces,in the South the China European region Province [5]. Bradoriids and the have Four-A’s been(4A) utilized Province to define consisting two paleobiogeographic of America, Asia, Australia,provinces, andthe AntarcticaEuropean [Province25]. The 4Aand province the Four-A’s has a warmer,(4A) Province more tropical consisting aspect. of America,Hipponicharion Asia, showsAustralia, affinities and Antarctica to East and [25]. West The Gondwana, 4A province with has occurrences a warmer, also more in Laurentia tropical aspect. and South Hipponicharion China [31]. Albrunnicolashows affinitiesis so to far East restricted and West to Laurentia,Gondwana, Australia with occurrences and Antarctica also in [31 Laurentia]. Beyrichona andwas South endemic China to[31]. Laurentia, Albrunnicola Baltica, is so Avalonia far restricted and South to Laurentia, China [31 ].Australia Facies dependenciesand Antarctica and [31]. ecological Beyrichona factors, was plusendemic an increasingly to Laurentia, rich Baltica, data set Avalonia such as Indianaand Soutturningh China up [31]. in Germany, Facies dependencies may, however, and weaken ecological any biogeographicfactors, plus an signals increasingly [19]. Nevertheless, rich data set the such distribution as Indiana of turningIndiana up[19 in] is Germany, in accord may, with anhowever, earlier paleobiogeographicweaken any biogeographic analysis signals that linked[19]. Nevertheless, Avalonia, Baltica the distribution and Laurentia of Indiana using [19] the is endemicin accord stemwith brachiopodan earlier paleobiogeographicMickwitzia [116]. analysisPseudobeyrichona that linkedfrom Avalonia, both China Baltica and and Germany Laurentia suggests using the that endemic West Gondwanastem brachiopod (Germany) Mickwitzia hosted [116]. both Pseudobeyrichona typically western from and both eastern China bradoriid and Germany taxa [19 suggests]; thus, this that part West of EuropeGondwana has a(Germany) very long historyhosted both of being typically a crossroads western between and eastern East andbradoriid West. taxa [19]; thus, this part of EuropeThe biogeographic has a very long significance history of ofbeCambroarchilocusing a crossroads tigrisbetweengen. East nov. and sp. West. nov. was first assessed by SiveterThe and biogeographic Williams [20 ],significance who considered of Cambroarchilocus it the southern-most tigris gen. (present nov. sp. day nov. coordinates) was first assessed occurrence by ofSiveter bradoriids and Williams in North [20], America. who cons Strengidered and it coauthors the southern-most [69] noted (present that Cambroarchilocus day coordinates) tigris occurrencegen. nov. sp.of bradoriids nov. “might in North provide America. further Streng clues to and bradoriid coauthors distribution [69] noted patterns that Cambroarchilocus and confirm biogeographictigris gen. nov. asp.ffi nitiesnov. “might between provide Baltica further and Laurentia.” clues to bradoriid Peel [31] distribution plotted Cambroarchilocus patterns and tigrisconfirmgen. biogeographic nov. sp. nov. (asaffinities ?Albrunnicola between) onBaltica a Cambrian and Laurentia.” Series 2 paleobiogeographic Peel [31] plotted Cambroarchilocus base map, inferring tigris agen.ffinities nov.between sp. nov. southern(as ?Albrunnicola Laurentia) on and a Cambrian Australia/ AntarcticaSeries 2 paleobiogeographic based on the distribution base map, of Albrunnicola inferring affinities. Recognition between of Cambroarchilocus in other parts of the world could potentially generate key paleobiogeographic data for assessing early Cambrian provinciality. I predict here that Cambroarchilocus will be discovered in Cambrian strata of Antarctica along with other currently unknown bradoriids of the 4A Province.

8. Systematic Paleontology Repository data: Specimens are located in the IGM repository, Institute of Geology Museum, Departmento de Palaeontología, Cuidad Universitaria, Delegacíon, 04510, México. Geosciences 2020, 10, x FOR PEER 27 of 37 southern Laurentia and Australia/Antarctica based on the distribution of Albrunnicola. Recognition of Cambroarchilocus in other parts of the world could potentially generate key paleobiogeographic data forGeosciences assessing 2020, 10 , earlyx FOR PEERCambrian provinciality. I predict here that Cambroarchilocus27 willof 37 be discovered in Cambrian strata of Antarctica along with other currently unknown bradoriids of the southern Laurentia and Australia/Antarctica based on the distribution of Albrunnicola. Recognition 4A Province. of Cambroarchilocus in other parts of the world could potentially generate key paleobiogeographic data for assessing early Cambrian provinciality. I predict here that Cambroarchilocus will be 8. Systematic Paleontology discovered in Cambrian strata of Antarctica along with other currently unknown bradoriids of the Repository4A Province. data: Specimens are located in the IGM repository, Institute of Geology Museum, Departmento de Palaeontología, Cuidad Universitaria, Delegacíon, 04510, México. 8. Systematic Paleontology Repository data: SpecimensPhylum Euarthropodaare located in the Lankester, IGM repository, 1904 [117] Institute of Geology Museum, GeosciencesDepartmento2020, 10 ,de 119 Palaeontología, CuidadClass Universitaria, unknown Delegacíon, 04510, México. 27 of 37 Order Bradoriida Raymond, 1935 [1] Phylum Euarthropoda Lankester, 1904 [117] Family Hipponicharionidae Sylvester-Bradley, 1961 [7] Class unknown PhylumGenus Euarthropoda Cambroarchilocus Lankester, nov. 1904 gen. [117 ] Order Bradoriida Raymond, 1935 [1] Class unknown Family HipponicharionidaeOrder Bradoriida Raymond, Sylvester-Bradley, 1935 [1] 1961 [7] Type species: monotypic, Cambroarchilocus tigris gen. nov. sp. nov. Family HipponicharionidaeGenus Cambroarchilocus Sylvester-Bradley, nov. gen. 1961 [7] Etymology: Named for the CambrianGenus Cambroarchilocus System, andnov. gen.to reflect diminutive size as in the hummingbirdType Archilocus species: monotypic,, and also Cambroarchilocusfor the Greek lyric tigris poet gen. Archilocusnov. sp. nov. ( c. 680 - c. 640 BC), who wrote Type species: monotypic, Cambroarchilocus tigris gen. nov. sp. nov. of a shield Etymology:that was discarded Named (forcf. bradoriidthe Cambrian extinction) System, to andbe replaced to reflect by diminutivea new shield size (cf. as appearance in the Etymology: Named for the Cambrian System, and to reflect diminutive size as in the hummingbird of ostracods):hummingbird Archilocus, and also for the Greek lyric poet Archilocus (c. 680 - c. 640 BC), who wrote Archilocus, and also for the Greek lyric poet Archilocus (c. 680 - c. 640 BC), who wrote of a shield that Ἀσπίδιof a shield μὲν thatΣαΐων was τις discarded ἀγάλλεται (cf., bradoriid ἥν παρὰ θάμνῳextinction) to be replaced by a new shield (cf. appearance was discarded (cf. bradoriid extinction) to be replaced by a new shield (cf. appearance of ostracods): of ostracods): ἔντος ἀμώμητον κάλλιπον οὐκ ἐθέλων·

αὐτὸνἈσπίδι δ' ἔκ μ μὲν' ἐσάωσα Σαΐων· τιςτί μοιἀγάλλεται μέλει ἀσπὶς, ἥν παρὰ ἐκείνη θάμνῳ; ἔντος ἀμώμητον κάλλιπον οὐκ ἐθέλων· Ἐρρέτω· ἐξαῦτις κτήσομαι οὐ κακίω. [118] αὐτὸν δ' ἔκ μ' ἐσάωσα· τί μοι μέλει ἀσπὶς ἐκείνη; One of the Thracians now delights in the shield I discarded Ἐρρέτω· ἐξαῦτις κτήσομαι οὐ κακίω. [118] Unwillingly near a bush, for it was perfectly fine, [118] One of the Thracians now delights in the shield I discarded But at least I safely escaped. Why should I pine for that shield? Unwillingly near a bush, for it was perfectly fine, LetBut it at go. least I'll I latersafely find escaped. another Wh yone should as good. I pine for that shield? Let it go. I'll later find another one as good.

Diagnosis:Diagnosis: A prepleteA preplete hipponicharionid hipponicharionid bradoriid bradoriid withwith a a well-delimited well-delimited posterior posterior lobe lobe with with a a well-definedwell-definedDiagnosis: sulcus sulcus on A onprepleteits itsanterior anterior hipponicharionid side, side, a aweak weak anterodorsalbradoriid anterodorsal with lobe lobe a well-delimited that that overhangs overhangs posterior the the dorsal dorsal lobe margin, with margin, a and aand well-definedstrongly a strongly inflated sulcus inflated anterior on anterior its anterior shield. shield. side, Appendages Appendages a weak an terodorsal unknown.unknown. lobe that overhangs the dorsal margin, Discussion:andDiscussion: a strongly Cambroarchilocus inflatedCambroarchilocus anterior shield.nov.nov. gen. gen.Appendages is is most most unknown. closely alliedalli ed to to three three other other hipponicharionid hipponicharionid bradoriidDiscussion: genera, Hipponicharion Cambroarchilocus, Albrunnicola nov. gen.and is mostBeyrichona closely. All alli foured generato three have other the hipponicharionid deep triangular bradoriid genera, Hipponicharion, Albrunnicola and Beyrichona. All four genera have the deep valvesbradoriid characteristic genera, Hipponicharion for the family, (a Albrunnicola morphology and possibly Beyrichona related. All toactivity four genera of the AntphaveTgl theallele), deep triangular valves characteristic for the family (a morphology possibly related to activity of the AntpTgl buttriangular the latter valves three havecharacteristic a better developedfor the family anterodorsal (a morphology lobe than possibly seen related in Cambroarchilocus to activity of, andthe Antp noneTgl allele),ofallele), thebut three the but latter are the preplete latter three three ashave is haveCambroarchilocus a better a better developed developed. anterodorsal anterodorsal lobe thanthan seen seen in in Cambroarchilocus Cambroarchilocus, , and noneandCambroarchilocus ofnone the of three the three are prepleteare tigris prepletenov. as gen. isas Cambroarchilocusis nov. Cambroarchilocus sp.: Figures. 31. –37 CambroarchilocusCambroarchilocus tigris tigris nov. nov. gen. gen. nov. nov. sp.: sp.: Figures Figures 31–37 31–37

Figure 31. Cambroarchilocus tigris gen. nov. sp. nov. Holotype. Left shield, anterior to left. IGM 3614 (42). Photo Credit: Mark McMenamin. Geosciences 2020, 10, x FOR PEER 28 of 37 Geosciences 2020, 10, x FOR PEER 28 of 37 Figure 31. Cambroarchilocus tigris gen. nov. sp. nov. Holotype. Left shield, anterior to left. IGM 3614 Geosciences(42).Figure Photo2020 31., 10 CambroarchilocusCredit:, 119 Mark McMenamin. tigris gen. nov. sp. nov. Holotype. Left shield, anterior to left. IGM 361428 of 37 (42). Photo Credit: Mark McMenamin.

Figure 32. Cambroarchilocus tigris gen. nov. sp. nov. Holotype. Left shield, detail of posterodorsal node andFigure posterior 32. CambroarchilocusCambroarchilocus cardinal corner. tigris Anterior gen. nov. to le sp. ft. nov.IGM nov. Holotype. Holotype.3614 (42). LeftPhoto Left shield, shield, Credit: detail detail Mark of of McMenamin.posterodorsal posterodorsal node and posterior cardinal corner. Anterior to left.left. IGM 3614 (42). Photo Credit: Mark Mark McMenamin. McMenamin.

Figure 33. Cambroarchilocus tigris gen. nov. sp. nov. Paratype. Right shield, anterior to right. Hinge Figure 33. Cambroarchilocus tigris gen. nov. sp. nov. Paratype. Right shield, anterior to right. Hinge area areaFigure broken. 33. Cambroarchilocus Irregular lump tigristo at rightgen. nov.edge sp.of fonov.ssil isParatype. an adhering Righ graint shield, of sediment.anterior to Arcuate right. Hinge scars broken. Irregular lump to at right edge of fossil is an adhering grain of sediment. Arcuate scars along alongarea broken. ventral Irregularmargin attributed lump to athere right to Arcuoichnusedge of fossil pierci is an nov. adhering ichnogen. grain nov. of sediment.ichnosp. IGM Arcuate 3614 scars(43). ventral margin attributed here to Arcuoichnus pierci nov. ichnogen. nov. ichnosp. IGM 3614 (43). Photoalong ventralCredit: Markmargin McMenamin. attributed here to Arcuoichnus pierci nov. ichnogen. nov. ichnosp. IGM 3614 (43). Photo Credit: Mark McMenamin.

Figure 34. Cambroarchilocus tigris gen. nov. sp. nov. Paratype. Right shield, anterior to right. Detail of ‘fingerprint’ ridges in the sulcus anterior to the posterodorsal node. IGM 3614 (43). Photo Credit:

Mark McMenamin.

Geosciences 2020, 10, x FOR PEER 29 of 37

GeosciencesFigure 2020 34., 10 Cambroarchilocus, x FOR PEER tigris gen. nov. sp. nov. Paratype. Right shield, anterior to right. Detail 29of of 37 ‘fingerprint’ ridges in the sulcus anterior to the posterodorsal node. IGM 3614 (43). Photo Credit: Mark Figure 34. Cambroarchilocus tigris gen. nov. sp. nov. Paratype. Right shield, anterior to right. Detail of McMenamin. Geosciences‘fingerprint’2020, 10, ridges 119 in the sulcus anterior to the posterodorsal node. IGM 3614 (43). Photo Credit: Mark29 of 37 McMenamin.

Figure 35. Cambroarchilocus tigris gen. nov. sp. nov. Paratype. Right shield, anterior to right. Detail of ‘fingerprint’ ridges and flat marginal rim at the anterior edge of the shield. An example of Arcuoichnus Figure 35. Cambroarchilocus tigris gen. nov. sp. nov. Paratype. Right shield, anterior to right. Detail of pierci nov. ichnogen. nov. ichnosp. occurs at lower right in the image. IGM 3614 (43). Photo Credit: ‘fingerprint’‘fingerprint’ ridgesridges andand flatflat marginalmarginal rimrim atat thethe anterioranterior edgeedge ofof thethe shield. An An example example of of ArcuoichnusArcuoichnus Mark McMenamin. pierci nov. ichnogen. nov. ichnosp. occurs occurs at at lower right in the image. IGM 3614 (43). Photo Photo Credit: Mark McMenamin.

Figure 36. Cambroarchilocus tigris gen. nov. sp. nov. Reconstruction of left shield, anterior to left. ReconstructionFigure 36. Cambroarchilocus based on both tigris the holotype gen. nov. and sp. paratype. nov. Reconstruction Width of shield of 1.5left mm. shield, Abbreviations: anterior to adnleft., anterodorsalReconstruction node; basedamr on, admarginal both the holotype rim; pdr ,and posterodorsal paratype. Width node, * of= anterodorsalshield 1.5 mm. cardinal Abbreviations: marginal Figure 36. Cambroarchilocus tigris gen. nov. sp. nov. Reconstruction of left shield, anterior to left. Geosciencesconcavity.adn, 2020anterodorsal, 10 Image, x FOR Credit: PEERnode; Markamr, McMenamin.admarginal rim; pdr, posterodorsal node, * = anterodorsal cardinal30 of 37 Reconstruction based on both the holotype and paratype. Width of shield 1.5 mm. Abbreviations: marginal concavity. Image Credit: Mark McMenamin. adn, anterodorsal node; amr, admarginal rim; pdr, posterodorsal node, * = anterodorsal cardinal marginal concavity. Image Credit: Mark McMenamin.

Figure 37. Cambroarchilocus tigris gen. nov. sp. nov. nov. Reconstruction Reconstruction of left valve, anterior to left (shown here withoutwithout thethe admarginaladmarginal rim). rim). Reconstruction Reconstruction based based on on both both the the holotype holotype and and paratype. paratype. Width Width of shieldof shield 1.5 1.5 mm. mm. Image Image Credit: Credit: Mark Mark McMenamin, McMenamin, using using Scuptris Scuptris Alpha Alpha 6 by 6 by Pixologic, Pixologic, Inc. Inc.

Synonymy: ostracod cf. Bradoria McMenamin and McMenamin 1990 [119] phosphatic ostracod McMenamin et al. 1994 [120] hipponicharionid Siveter and Williams 1997 [20] bradoriid ostracod McMenamin 2001 [121] bradoriid Zhang 2007 [106] ?Albrunnicola Streng et al. 2008 [69] ?Albrunnicola Peel 2017 [31] Holotype: Field sample MM-82-49; IGM 3614 (42); left shield. Paratype: Field sample MM-82-49; IGM 3614 (43); right shield. Etymology: From Latin from Greek tigris (tiger), for its stripe-like type A1 striation ridge banding, and for the tiger rattlesnake (Croatus tigris) that guarded the trail leading into the southern Cerro Rajón field locality in Sonora, México (see p. 201 in reference [122]). Diagnosis: Same as for genus, by monotypy. Description: The Cambroarchilocus tigris nov. gen. nov. sp. holotype is a left valve 1.8 mm in greatest dimension. High P and Ca peaks on an SEM-EDS analysis of the holotype, plus the fact that the fossil was recovered by acetic acid maceration of the enclosing archaeocyathan limestone, indicate that the specimens are of hydroxyapatitic composition. The lateromarginal ridge is relatively wide. Exterior shield ornamentation consists of fine subparallel ridges comparable to the type A1 (‘concentric striation’) of Siveter and Williams [20]. Although the hinge area is partly damaged, a faint dorsal cusp is visible. The posterior lobe is elongate, and oriented an approximate 50° angle to the vertical posterior edge of the shield. A sulcus occurs just anterior to the posterior lobe. The paratype is a partially complete right valve 1.4 mm in greatest dimension (Figures 33, 34, 35). The anterodorsal lobe is elongate, slightly overhangs the hinge line, and its anterior edge is located adjacent to the broken edge of the valve. There is a medioventral division in the ridge formed by the connection of the ventral slopes of the anterior and posterior lobes. A prominent sulcus occurs posterior to the anterodorsal lobe. As with the holotype, the shield is covered with an ornament of fine, narrowly separated ridges. Subparallel striations (of type A1) occur as a series of ‘fingerprint’ ridges in the sulcus depression (Figure 34), and are similar to those appearing on the right valve of a specimen of Beyrichona papilio from the Hanford Brook Formation, New Brunswick on Plate 4, Figure 10 of Reference [20].

Geosciences 2020, 10, 119 30 of 37

Synonymy: ostracod cf. Bradoria McMenamin and McMenamin 1990 [119] phosphatic ostracod McMenamin et al. 1994 [120] hipponicharionid Siveter and Williams 1997 [20] bradoriid ostracod McMenamin 2001 [121] bradoriid Zhang 2007 [106] ?Albrunnicola Streng et al. 2008 [69] ?Albrunnicola Peel 2017 [31] Holotype: Field sample MM-82-49; IGM 3614 (42); left shield. Paratype: Field sample MM-82-49; IGM 3614 (43); right shield. Etymology: From Latin from Greek tigris (tiger), for its stripe-like type A1 striation ridge banding, and for the tiger rattlesnake (Croatus tigris) that guarded the trail leading into the southern Cerro Rajón field locality in Sonora, México (see p. 201 in reference [122]). Diagnosis: Same as for genus, by monotypy. Description: The Cambroarchilocus tigris nov. gen. nov. sp. holotype is a left valve 1.8 mm in greatest dimension. High P and Ca peaks on an SEM-EDS analysis of the holotype, plus the fact that the fossil was recovered by acetic acid maceration of the enclosing archaeocyathan limestone, indicate that the specimens are of hydroxyapatitic composition. The lateromarginal ridge is relatively wide. Exterior shield ornamentation consists of fine subparallel ridges comparable to the type A1 (‘concentric striation’) of Siveter and Williams [20]. Although the hinge area is partly damaged, a faint dorsal cusp is visible. The posterior lobe is elongate, and oriented an approximate 50◦ angle to the vertical posterior edge of the shield. A sulcus occurs just anterior to the posterior lobe. The paratype is a partially complete right valve 1.4 mm in greatest dimension (Figures 33–35). The anterodorsal lobe is elongate, slightly overhangs the hinge line, and its anterior edge is located adjacent to the broken edge of the valve. There is a medioventral division in the ridge formed by the connection of the ventral slopes of the anterior and posterior lobes. A prominent sulcus occurs posterior to the anterodorsal lobe. As with the holotype, the shield is covered with an ornament of fine, narrowly separated ridges. Subparallel striations (of type A1) occur as a series of ‘fingerprint’ ridges in the sulcus depression (Figure 34), and are similar to those appearing on the right valve of a specimen of Beyrichona papilio from the Hanford Brook Formation, New Brunswick on Plate 4, Figure 10 of Reference [20]. Discussion: The wide lateromarginal ridge in Cambroarchilocus tigris nov. gen. nov. sp. suggests that the animal was able to seal its valves with its body inside, and did not require its valves to stay constantly open [28]. In addition, the flat wide marginal rim would also make the shields more effective for flap swimming, with the posterodorsal lobes serving a hydrodynamic function similar to that of the anterior and posterior auricles of the Peruvian scallop Argopecten purpuratus [123]. Furthermore, the overhang of the dorsal margin by the anterior lobe in Cambroarchilocus tigris gen. nov. sp. nov. would add to the downstroke (assuming the valves could open all the way) of the shield wing, as in the fully opened position the shield wings would have to extend distally to a certain extent to accommodate the overhang of the two valves at the anterior end of the hinge line. This would also tend to stretch the hinge ligament or equivalent to a certain degree, possibly adding power to the downstroke of the hypothesized rowing motion. The preplete character of Cambroarchilocus tigris gen. nov. sp. nov. is confirmed by the presence of an anterodorsal cardinal marginal concavity (Figures 31, 36 and 37). This anterodorsal cardinal marginal concavity is comparable to that of Bengtson’s [73] Hipponicharion sp. from Kulpara, Parara Limestone, Australia, where the anterodorsal cardinal marginal concavity is clearly visible and marks the anterior end of the shield. A similar anterodorsal cardinal marginal concavity, only weakly concave to straight in this case, is also visible in Hipponicharion loculatum (Figure 15). Thus, at least Geosciences 2020, 10, 119 31 of 37 for the hipponicharionids, recognition of the anterodorsal cardinal marginal concavity is useful for determining the anterior corner of the shield. Indianid bradoriids may also develop this anterodorsal cardinal marginal concavity, as for instance in gen. et sp. indet. G of Bengtson [73]. The shield ornamentation, consisting of type A1 fine (‘concentric striation’), resembles that of Bradoria scrutator but does not reach the center of the shield [20]. A large crack running diagonally across the holotype shield (Figure 31) was naturally ‘healed’ by diagenetic recrystallization of hydroxyapatite. Polygonal patterning consisting of thin raised ridges on the surface of both specimens cuts across the A1-type concentric striations and thus appears to be a diagenetic effect although it may have some link to shield microstructure. Associated Ichnofossil: Arcuate perforations along the ventral margin of the paratype (Figures 33 and 35) are of roughly the same size and shape, subtending approximately 40◦ of arc, and are interpreted here as marks of a microdurophagous predator that attacked a living Cambroarchilocus tigris nov. gen. nov. sp. with shields closed for protection. I propose the name Arcuoichnus pierci nov. ichnogen. nov. ichnosp. for this trace fossil. This ichnospecies name also applies to minute ‘bite marks’ on the agnostid Peronopsis interstricta [124], as the approximate widths of the respective damage (130 microns for the bradoriid and 200 microns for the agnostid) are comparable. Note that damage by drilling predators has been documented from the ostracod fossil record [83], but not yet from bradoriids. Age and Locality Information: Cambrian Series 2, upper part of Stage 3, lower Nevadella Zone, ca. 515 million years. This was the point in geologic time when bradoriids reached their maximum diversity (Figure2). Stratigraphic position: Lower archaeocyathan limestone (MM-82-49) occurring 18.2 m above the base unit 3 of the Puerto Blanco Formation, Cerro Rajón area, Sonora, México [125]. Collection data: The fossil was recovered by acetic acid dissolution of limestone collected on March 10–11, 1982 under the auspices of the United States Geological Survey and the Consejo de Recursos Minerales (exercising a federal executive directive [see Plate 1 in reference [122]]). Specimens reside in the Institute of Geology Museum, Departmento de Palaeontología, Cuidad Universitaria, México.

Family unknown Genus Dielymella Ulrich and Bassler, 1931 [66] Dielymella? sp.: Figure 38 Geosciences 2020, 10, x FOR PEER 32 of 37

Figure 38. Dielymella? sp.sp. Phosphatic Phosphatic steinkern steinkern of of the the right right shield shield of of an an amplete bradoriid with a prominent dorsal cusp. IGM 3614 (44) (44).. Photo Credit: Mark Mark McMenamin. McMenamin.

Material: Field sample MM-82-49; IGM 3614 (44); steinkern of right shield. Description: This specimen represents the right half of a phosphatic amplete bradoriid steinkern that split in half almost exactly along the plane of commissure. The fossil resembles Dielymella recticardinalis angustata in terms of its narrowly-rounded posterior shield, as seen in Plate 9, Figure 5 of reference [20]. It differs from this subspecies by having a more obtuse anterodorsal cardinal angle, by having what appears to be a longer anterodorsal cardinal corner marginal concavity, and by having a more pronounced dorsal cusp than in Dielymella, more resembling that of cambriid [33]. Further description must await more complete material. Discussion: Phosphatization of bradoriids is well known [106], but they may also occur as small carbonaceous fossils [126]. The latter mode of preservation in Greenland has preserved first order spines of Spinospitella. The fact that bradoriid shields were flexible, plus the known cases of carbonaceous fossil preservation, suggest that their shields contained a significant amount of organic matter, which may have contributed to the formation of phosphatic steinkerns. Collection data: As for previous. Age and Locality Information: As for previous.

Competing Interests: Not applicable.

Acknowledgments: The author wishes to thank S.M. Awarmik, S. Kiemle, D.L. Schulte McMenamin, J.M. Morales-Ramirez, D. Pierce (hence Arcuoichnus pierci nov. ichnogen. nov. ichnosp.), J.H. Stewart, and G. Marchand for assistance with this research.

Conflicts of Interest: The authors declare no conflict of interest.

References

1. Raymond, P.E. Leanchoilia and other mid-Cambrian Arthropoda. Bull. Mus. Compa. Zool. 1935, 76, 205–230. 2. Williams, M.; Vannier, J.; Corbari, L.; Massabuau, J.-C. Oxygen as a driver of early arthropod micro-benthos evolution. PLoS ONE 2011, 6, e28183. 3. Hou, X.; Siveter, D.J.; Williams, M.; Waloszek, D.; Bergström, J. Appendages of the arthropod Kunmingella from the early Cambrian of China: Its bearing on the systematic position of the bradoriids and the fossil record of the Ostracoda. Philos. Trans. R. Soc. Lond. 1996, 351, 1131–1145. 4. Hou, X.; Siveter, D.J.; Williams, M.; Feng, X. A monograph of the bradoriid arthropods from the lower Cambrian of SW China. Trans. R. Soc. Edinb. Earth Sci. 2002, 92, 347–409. 5. Williams, M.; Siveter, D.J.; Popov, L.E.; Vannier, J.M.C. Biogeography and affinities of the bradoriid arthropods: Cosmopolitan microbenthos of the Cambrian seas. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2007, 248, 202–232.

Geosciences 2020, 10, 119 32 of 37

Material: Field sample MM-82-49; IGM 3614 (44); steinkern of right shield. Description: This specimen represents the right half of a phosphatic amplete bradoriid steinkern that split in half almost exactly along the plane of commissure. The fossil resembles Dielymella recticardinalis angustata in terms of its narrowly-rounded posterior shield, as seen in Plate 9, Figure5 of reference [20]. It differs from this subspecies by having a more obtuse anterodorsal cardinal angle, by having what appears to be a longer anterodorsal cardinal corner marginal concavity, and by having a more pronounced dorsal cusp than in Dielymella, more resembling that of cambriid [33]. Further description must await more complete material. Discussion: Phosphatization of bradoriids is well known [106], but they may also occur as small carbonaceous fossils [126]. The latter mode of preservation in Greenland has preserved first order spines of Spinospitella. The fact that bradoriid shields were flexible, plus the known cases of carbonaceous fossil preservation, suggest that their shields contained a significant amount of organic matter, which may have contributed to the formation of phosphatic steinkerns. Collection data: As for previous. Age and Locality Information: As for previous.

Competing Interests: Not applicable. Acknowledgments: The author wishes to thank S.M. Awarmik, S. Kiemle, D.L. Schulte McMenamin, J.M. Morales-Ramirez, D. Pierce (hence Arcuoichnus pierci nov. ichnogen. nov. ichnosp.), J.H. Stewart, and G. Marchand for assistance with this research. Conflicts of Interest: The authors declare no conflict of interest.

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