Estimating Dispersal and Evolutionary Dynamics in Diploporan Blastozoans (Echinodermata) Across the Great Ordovician Biodiversification Ve Ent

Home , Blastozoa, Diploporita, Hirnantian, Ordovician, Ordovician radiation, Paleocontinent

University of South Florida Scholar Commons

School of Geosciences Faculty and Staff Publications School of Geosciences

2020

Estimating Dispersal and Evolutionary Dynamics in Diploporan Blastozoans (Echinodermata) Across the Great Ordovician Biodiversification vE ent

Adriane R. Lam University of Massachusetts

Sarah L. Sheffield University of South Florida, [email protected]

Nicholas J. Matzke University of Auckland

Follow this and additional works at: https://scholarcommons.usf.edu/geo_facpub

Part of the Earth Sciences Commons

Scholar Commons Citation Lam, Adriane R.; Sheffield, Sarah L.; and Matzke, Nicholas J., "Estimating Dispersal and Evolutionary Dynamics in Diploporan Blastozoans (Echinodermata) Across the Great Ordovician Biodiversification Event" (2020). School of Geosciences Faculty and Staff Publications. 2291. https://scholarcommons.usf.edu/geo_facpub/2291

This Article is brought to you for free and open access by the School of Geosciences at Scholar Commons. It has been accepted for inclusion in School of Geosciences Faculty and Staff Publications by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. Paleobiology, 2020, pp. 1–23 DOI: 10.1017/pab.2020.24

Article

Estimating dispersal and evolutionary dynamics in diploporan blastozoans (Echinodermata) across the great Ordovician biodiversiﬁcation event

Adriane R. Lam†, Sarah L. Shefﬁeld† , and Nicholas J. Matzke

Abstract.—Echinoderms make up a substantial component of Ordovician marine invertebrates, yet their speciation and dispersal history as inferred within a rigorous phylogenetic and statistical framework is lacking. We use biogeographic stochastic mapping (BSM; implemented in the R package BioGeoBEARS) to infer ancestral area relationships and the number and type of dispersal events through the Ordovician for diploporan blastozoans and related species. The BSM analysis was divided into three time slices to ana- lyze how dispersal paths changed before and during the great Ordovician biodiversification event (GOBE) and within the Late Ordovician mass extinction intervals. The best-fit biogeographic model incorporated jump dispersal, indicating this was an important speciation strategy. Reconstructed areas within the phylogeny indicate the first diploporan blastozoans likely originated within Baltica or Gondwana. Dispersal, jump dispersal, and sympatry dominated the BSM inference through the Ordovician, while dispersal paths varied in time. Long-distance dispersal events in the Early Ordovician indicate distance was not a significant predictor of dispersal, whereas increased dispersal events between Baltica and Laurentia are apparent during the GOBE, indicating these areas were important to blastozoan speciation. During the Late Ordovician, there is an increase in dispersal events among all paleocontinents. The drivers of dispersal are attributed to oceanic and epicontinental currents. Speciation events plotted against geochemical data indicate that blastozoans may not have responded to climate cooling events and other geochemical perturbations, but additional data will continue to shed light on the drivers of early Paleozoic blastozoan speciation and dispersal patterns.

Adriane R. Lam. *Department of Geological Sciences and Environmental Studies, Binghamton University, 4400 Vestal Parkway East, P.O. Box 6000, Binghamton, New York 13902, U.S.A.; and Department of Geosciences, University of Massachusetts Amherst, 627 North Pleasant Street, 233 Morrill Science Center, Amherst, Massachusetts 01003, U.S.A. E-mail: [email protected]. *Present address: Department of Geological Sciences and Environmental Studies, Binghamton University, 4400 Vestal Parkway East, P.O. Box 6000, Binghamton, New York 13902, U.S.A. Sarah L. Shefﬁeld. School of Geosciences, University of South Florida, 4202 East Fowler Avenue NES 107, Tampa, Florida 33620, U.S.A. E-mail: sshefﬁ[email protected] Nicholas J. Matzke. School of Biological Sciences, University of Auckland, 3A Symonds Street, Auckland Central, Auckland 1010, New Zealand. E-mail: [email protected]

Accepted: 13 May 2020 Data available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.4tmpg4f6j † These authors contributed equally to this work and are therefore listed alphabetically by last name.

Introduction shifts in geochemical cycles (Haq and Schutter 2008; Trotter et al. 2008; Rasmussen et al. Echinoderms show complex patterns of mor- 2016; Albanesi et al. 2019) that impacted micro- phological disparity and taxonomic diversity fossil and marine invertebrate groups (reviewed throughout their evolutionary history (Sumrall in Stigall et al. 2019), suggesting that blastozoan 1997; Deline 2015; Deline and Thomka 2017; echinoderms would have been impacted. Deline et al. 2020) and have been suggested to However, there are limited studies that have respond to long-term environmental and analyzed the paleobiogeography of extinct echi- climatic patterns (Paul 1968; Clausen 2004; noderms to infer how they evolved and dispersed Dickson 2004; Clausen and Smith 2005, 2008; in response to major climatic perturbations. Zamora and Smith 2008; Rahman and Zamora Of the blastozoan echinoderms, we primarily 2009). The early Paleozoic experienced large focus on the Diploporita in this study.

© 2020 The Paleontological Society. All rights reserved. This is an Open Access article, distributed under the terms of the DownloadedCreative from https://www.cambridge.org/core Commons Attribution licence. IP address: (http://creativecommons.org/licenses/by/4.0/ 173.168.155.110, on 14 Jul 2020 at 23:42:57, subject to the), Cambridge which permits Core terms unrestricted of use, available at https://www.cambridge.org/core/termsre-use, distribution, and reproduction. https://doi.org/10.1017/pab.2020.24 in any medium, provided the original work is properly cited. 0094-8373/20 2 ADRIANE R. LAM ET AL.

Diploporitan echinoderms (Ordovician– understand patterns of evolution and dispersal, Devonian) appeared in the fossil record in as two of the largest diversity booms and busts Lower Ordovician rocks in the Prague Basin, occur within this period: the great Ordovician and quickly gained high biogeographic diver- biodiversification event (GOBE) and the Late sity and morphological disparity (Lefebvre Ordovician mass extinction (LOME). To date, et al. 2013); all three large groupings within there is no information regarding the speciation Diploporita (i.e., Asteroblastida, Sphaeroni- types and dispersal patterns of diploporan tida, and Glyptosphaeronitida) are found in species, and few regarding echinoderms (a not- similarly aged strata within the Prague Basin. able exception being Bauer 2020) within a rigor- Diploporitans were originally placed in the ous phylogenetic and statistical framework same group by the presence of diplopore through the Ordovician Period. As diploporans (double-pore) respiratory structures, as all blas- were likely reevolving respiratory structures tozoan groups are traditionally classified by through their evolutionary history, it is critical their respiratory structures (Sprinkle 1973). to assess why this pattern occurred. During However, it is suspected that many groups of the Ordovician, organisms like diploporans blastozoans are not monophyletic and that and other blastozoans were likely responding respiratory structures might be convergent to changing conditions, such as increasing (Paul 1988; Sumrall 2010; Sheffield and Sumrall oxygen levels (e.g., Lenton et al. 2018), by 2017, 2019a). Sheffield and Sumrall (2019a), the evolving these respiratory structures and first study to place diplopore-bearing echino- other morphological features. derms within a phylogenetic framework, con- In this contribution, we use the R package cluded that Diploporita is likely polyphyletic BioGeoBEARS (Matzke 2013) to infer the bio- and diplopores have evolved more than once geographic history of the diploporans through in echinoderms. As Diploporita is not a real the entire Ordovician Period. Further analysis evolutionary grouping, we refer to diplopore- of the patterns of dispersal and speciation bearing blastozoans as diploporans herein. within the group is investigated using biogeo- While biogeographic patterns of blastozoan graphic stochastic mapping (BSM; Dupin echinoderms have been explored to a degree et al. 2017). These analyses are conducted to (e.g., Lefebvre 2007; Nardin and Lefebvre (1) investigate the origin of the diploporan echi- 2010; Lefebvre et al. 2013; Zamora et al. 2013), noderms; (2) assess the contribution of vicari- these studies have treated blastozoan groups ance, dispersal, and founder-event speciation as monophyletic, which can limit our under- (or “jump dispersal”) that led to the early standing of biogeographic and evolutionary Paleozoic radiation of the diploporans; and patterns. Further, these studies have largely (3) reconstruct the source and directionality of been conducted by analyzing the counts of dispersal events before, during, and after the echinoderm taxa within stratigraphic locations, GOBE. not through phylogenetic methods. Similarly, many studies of diversity curves, origination, Background and extinction rates of Paleozoic echinoderms have been conducted at the genus level, with- The Ordovician Earth System.—The Ordovi- out the context of evolution (e.g., Nardin and cian Period (485.4–443.8 Ma; Ogg et al. 2016)was Lefebvre 2010). Interpretation of such patterns a time of increased tectonic activity, widely dis- of evolution within a phylogenetic framework persed continents, and major climatic shifts. is important, because biogeographic processes Throughout the entire study interval, volcanic are critical for understanding large-scale pat- island arcs fringed the major paleocontinents terns in biodiversity and paleoecology through and terranes (e.g., Fitton and Hughes 1970;Ped- time, particularly through the Middle to Late ersen et al. 1992;Harperetal.1996; Glen et al. Ordovician (e.g., Miller 1997; Wright and Sti- 1998; Cocks and Torsvik 2011;Samygin2019; gall 2013; Trubovitz and Stigall 2016; Lamsdell Zhang et al. 2019), especially within the Iapetus et al. 2017; Stigall et al. 2017). The Ordovician is Ocean (Rasmussen and Harper 2011; Liljeroth a critical time to investigate in order to et al. 2017). These tectonic and climatic factors

Downloaded from https://www.cambridge.org/core. IP address: 173.168.155.110, on 14 Jul 2020 at 23:42:57, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/pab.2020.24 EVOLUTIONARY DYNAMICS OF DIPLOPORAN ECHINODERMS 3

undoubtedly had a large influence on the bio- column characterized by oxygen-poor and geographic patterns and evolutionary history of phosphate-rich conditions that lasted until the blastozoan echinoderms. earliest Katian Age (Wilde 1991; Kolata et al. The Early Ordovician was characterized by 2001; Young et al. 2015; Quinton et al. 2017). relatively high sea level, with the Iapetus With the initiation of cool oceanic waters into Ocean at its widest. Continents were at their Laurentia and expansion of the Sebree Trough most widely distributed due to increased rates (Young et al. 2015), warm carbonate platform of seafloor spreading and high continental deposition was replaced with mixed cool-water drift rates for Baltica, Siberia, Gondwana, and carbonate and clastic facies throughout eastern Avalonia (Scotese and McKerrow 1991; van central Laurentia (Keith 1989; Ettensohn et al. de Pluijm et al. 1995; Harper et al. 1996; Cocks 2002). Warm-water carbonate facies resumed and Torsvik 2011). Throughout the Ordovician, during the Late Ordovician Katian Age the Iapetus Ocean between Laurentia and (Ettensohn et al. 2002). Baltica constricted, leading to the eventual Throughout the Ordovician, several climatic collision of Laurentia, Baltica, and Avalonia in shifts occurred, leading to a transition from a the latest Ordovician to early Silurian (Hutton greenhouse to an icehouse world. The Early and Murphy 1987; Soper et al. 1992; Cocks Ordovician was characterized by very warm and Torsvik 2011; Zagorevski and Van Staal global average temperatures, with perhaps 2011). shorter-term cooling intervals (Trotter et al. Several tectonic events characterized 2008; Albanesi et al. 2019) and high global sea the Ordovician Period, with the one most level, punctuated by shorter-term sea-level impactful to the Laurentian-centric blastozoans falls (Haq and Schutter 2008). A shift to a cooler being the Taconian orogeny. Within Laurentia, climate began in the late Early Ordovician the initiation of the Taconian orogeny Floian Age, which continued into the Middle Blountian tectophase began along the southern Ordovician and intensified in the Late Ordovi- margin of the paleocontinent during the Mid- cian (Trotter et al. 2008; Finnegan et al. 2011; dle Ordovician (Ettensohn 2010). During this Albanesi et al. 2019). Several studies based tectophase, the accretion of small island arcs upon geochemistry, paleoecology, backstrip- and microcontinents led to the formation of ping, and sea-level changes on a stable margin the Sevier foreland basin that stretched from indicate that continental glaciations occurred present-day Alabama to Virginia (Shanmugam during the Middle Ordovician, potentially as and Lash 1982; Ettensohn 2010). This narrow early as the Darriwilian Age (Vandenbroucke basin was characterized by major clastic et al. 2009; Turner et al. 2012; Dabard et al. wedges (Ettensohn 2004) that did not interrupt 2015; Amberg et al. 2016; Pohl et al. 2016a; Ras- tropical carbonate sedimentation across the mussen et al. 2016). Cooling continued into the southern margin of Laurentia (Holland and Late Ordovician with well-developed continen- Patzkowsky 1997). The Taconic tectophase tal ice sheets over west Gondwana responding began during the early Late Ordovician, with to orbital forcing (Beuf et al. 1971; Hambrey the locus of tectonic activity moving east 1985; Crowley and Baum 1991; Eyles 1993;Cro- toward present-day New York (Ettensohn well 1999; Scotese et al. 1999; Sutcliffe et al. et al. 1991; Ettensohn 2010). Nearly synchron- 2000; Sinnesael et al. 2019). ous with this event was the creation of the Seb- Modeling experiments under different ree Trough, a narrow depression that stretched atmospheric carbon dioxide (CO2) conditions from the southwestern edge of Laurentia have reconstructed wind-driven surface circu- toward the midcontinent region, terminating lation throughout the Ordovician Period, near present-day Ohio (Kolata et al. 2001). allowing comparisons of reconstructed disper- This trough funneled cooler Iapetus waters sal paths to current and gyre flow directions. into the craton, which may have led to mixing Five major ocean gyre systems operated within of different water masses and a change in the Ordovician ocean (Poussart et al. 1999; intracratonic circulation patterns. Cooler Herrmann et al. 2004; Pohl et al. 2016b; waters generated a density-stratified water Fig. 1). In addition to major gyre systems,

FIGURE 1. Paleogeographic map of the Middle Ordovician Darriwilian Age with major ocean currents (solid lines) and gyre systems (dotted lines). Geographic basins deﬁned in this study are denoted by letters as follows: G, Gondwana; B, Baltica; S, southern Laurentia; P, northern Appalachian Basin; A, southern Appalachian Basin; C, Cincinnati Basin; W, western midcontinent; and R, north of the Transcontinental Arch. Basin letters are the same as those in Fig. 2. Ocean gyres are numbered as follows: 1, north Panthalassic convergence; 2, south Panthalassic convergence; 3, south Paleo-Tethys convergence; 4, north Paleo-Tethys convergence; and 5, Rheic convergence. Ocean currents are abbreviated as follows: NEC, north equatorial current SEC, south equatorial current; IC, Iapetus Current; SLC, southern Laurentia Current; AC, Antarctica Current; SW, southern westerlies; and GC, Gondwanan westerlies. Paleogeographic map is modiﬁed from Tors- vik and Cocks (2013), with the approximate locations of currents and gyre systems from Pohl et al. (2016b).

several currents flowed along the margins of to planktic, benthic, and nektonic groups all major continental land masses, such as the exhibit peak diversification rates within the Iapetus Current in the Iapetus Ocean. These Middle Ordovician Darriwilian Age. Thus, currents likely caused increased coastal upwell- the use of the term “GOBE” is now restricted ing and thus increased primary productivity only to the Darriwilian to indicate the rather along the margins of large paleocontinents, vol- short period of time when statistically elevated canic island arcs, and in the midlatitude regions diversification rates occurred (Kröger and (Pope and Steffen 2003; Pohl et al. 2018). Lintulaakso 2017). Biotic Events of the Ordovician.—The Ordovi- This expansion of diversification has been cian Period not only included substantial linked to extrinsic factors of the Ordovician changes in geochemical cycles and major cli- Earth system, of which many have been pro- matic shifts, but also a major boom (GOBE) posed, including: oceanic cooling, increased and bust (LOME) in microfossil and marine atmospheric oxygen levels, sea-level transgres- invertebrate diversity. sions, increased weathering and terrestrial The GOBE was a time in Earth’s history delivery of nutrients to the oceans, and spin-up when there were unparalleled amounts of of ocean gyres and currents in response to cool- diversity across multiple taxonomic groups, ing (Fortey 1984; Trotter et al. 2008; Saltzman primarily at the superfamily to species levels et al. 2015; Pohl et al. 2016a; Rasmussen et al. (Webby et al. 2004; Harper 2006; Stigall 2018; 2016; Trubovitz and Stigall 2016; Young et al. Stigall et al. 2019). At the family level, diversity 2016; Edwards et al. 2017; Lam et al. 2018). increased on average threefold, whereas gen- Increased atmospheric oxygen levels could eric diversity increased fourfold. In a recent have contributed to increased metabolic pro- review by Stigall et al. (2019), biota belonging cesses for marine invertebrates and allowed

for increased calcite precipitation (Pruss et al. Trough) and physical (such as the Transcontin- 2010). Tectonic activity created several volcanic ental Arch in western Laurentia) barriers that island arcs and microterranes surrounding existed between basins. Laurentian basins paleocontinents, which provided the means include the southern Appalachian Basin; nor- for species to accomplish long-distance disper- thern Appalachian Basin; Cincinnati Basin, sal among areas (Harper et al. 1996; Liljeroth southern Laurentia; north of the Transcontin- et al. 2017; Lam et al. 2018). All of these factors ental Arch; and the western midcontinent primed the Ordovician Earth system and its (Fig. 1). The Laurentian basins follow marine biota for the GOBE, as the evolutionary mech- invertebrate and microfossil provinces (e.g., anism that led to an increase in biodiversity conodonts, ostracods, corals, brachiopods; was likely produced in part by a series of Amsden 1974, 1986; Thompson and Satterfield dispersal and vicariance events, termed “biotic 1975; Elias 1983; Barrick 1986; Mohibullah et al. immigration events” (BIMES; Stigall et al. 2012). Laurentia is split into several areas due to 2017). increased sampling and species occurrences in Concurrent with the latest Ordovician was North America, which allows for finer-scale the LOME, which occurred in two major pulses paleobiogeographic analyses. Additional (Brenchley et al. 1994; Brenchley 1995; Brench- basins include the paleocontinents of Gon- ley and Marshall 1999), the first occurring at dwana and Baltica. We have grouped Russia, the Katian/Hirnantian boundary and the located on the paleo-terrane of Siberia, with second at the end of the Hirnantian Age. The Gondwana in this study (Fig. 1), as only one first pulse of the extinction is closely linked species occurs in this area, and that occurrence with the rapid growth of continental ice sheets is questionable (Supplementary Table 1). The on Gondwana causing glacioeustatic sea-level basins in this study follow those defined in and temperature decreases (Finnegan et al. Lam et al. (2018) so a direct comparison 2011). Genera that mainly occupied epicontin- among dispersal paths could be made for the ental seas were hit hardest by this first extinc- blastozoan echinoderms in this study and bra- tion pulse as these seaways drained, reducing chiopods and trilobites studied in Lam et al. the amount of available niche space (Finnegan (2018). et al. 2012, 2016). Modeling studies indicate The fossil record of the blastozoans, particu- the combined effects of Ordovician paleogeog- larly in groups like the diploporans, which do raphy along with relatively fast cooling and not often preserve in high numbers, is still eustatic sea-level fall are factors that help lacking, but progress over recent years (e.g., explain the severity of the first LOME pulse Sumrall et al. 2013, 2015; Zamora et al. 2016; (Saupe et al. 2020). The second pulse of the Sheffield et al. 2017; Sumrall and Zamora LOME corresponds to receding glaciers and 2018) has shed light on the evolutionary history warming that may have caused other environ- of this group, especially in relatively unexplored mental perturbations, such as warming oceans areas of the globe. Here, we utilized the phyl- and anoxic waters transgressing into shelf areas ogeny developed by Sheffield and Sumrall (Brenchley et al. 1994; Sheehan 2001; Melchin (2019a), which tested the hypothesis that Diplo- et al. 2013). More recent studies hint that large porita was not a monophyletic group of echino- igneous province (LIP) emplacement in the derms. To test this hypothesis, other groups of Late Ordovician, as inferred from mercury- echinoderms (e.g., crinoids, eocrinoids, rhombi- enrichment episodes, could have been a pri- ferans) were included in the analysis. This mary driver of the LOME (Jones et al. 2017). tree ranges from the Cambrian to Devonian (Fig. 2); however, because the majority of speci- Methods ation events occur in the Ordovician, we focus on reconstructing patterns of dispersal and Geographic Framework and Species Occur- speciation within this period only. rences.—We defined eight biogeographic For species utilized in this study, their strati- areas, with six of them within Laurentia graphic and geographic occurrence data were (Fig. 1) based on thermal (such as the Sebree compiled from published literature sources,

FIGURE 2. Maximum-likelihood ancestral range estimation of the diploporan and other related blastozoan species within the DIVALIKE + j model. A, Pie charts indicating the probabilities of ancestral ranges at the nodes of the phylogeny. B, Most likely areas as inferred from the pie charts in A. Using these estimates, dispersal (range expansion) and vicariance events were interpreted through the tree. The three time slices used in the biogeographic stochastic mapping (BSM) analysis are denoted beside global chronostratigraphy in the gray boxes. Area letter denotations and colors are the same as in Figs. 1 and 4. Chronostratigraphy and age from the Geologic Time Scale 2016 (Ogg et al. 2016). Refer to Supplementary Table 1 for species’ groupings within Echinodermata. Fossil image of diploporan Eumorphocystis multiporata Branson and Peck 1940,SUI97599, modiﬁed from Shefﬁeld and Sumrall (2019b).

the Paleobiology Database, and FossilID Time-Calibrated Phylogenetic Hypothesis.— (https://fossiilid.info; Supplementary Table 1). Shefﬁeld and Sumrall (2019a) constructed a Age-level occurrence data from published morphological character matrix of 61 characters literature sources were then updated to the (of which 41 were parsimony informative). Geologic Time Scale 2016 (Ogg et al. 2016) Twenty-eight taxa across Diploporita and using graptolite and conodont zones to gain other stemmed echinoderms were included in an estimate of species ranges for use in time- the analysis; this study primarily used taxa calibrating the blastozoan phylogeny. that the authors were able to study in person.

Parsimony-uninformative characters were using Bayesian tip-dating methods (Matzke removed from the analysis. A heuristic search and Wright 2016) in Beast2 (Bouckaert et al. of most parsimonious trees was run using a 2014). BEASTmasteR (Matzke 2019) was then tree–bisection–reconnection branch-swapping used to convert the data matrix into the XML algorithm with a reconnection limit of eight. format that is required for Beast2. The matrix was polarized using Gogia spiralis As fossil specimen temporal ranges are not Robison, 1965 as the out-group. The analysis known exactly, and the characters of each spe- recovered 18 optimal trees. The analysis pre- cies occur across the time range of that species, sented here uses the strict consensus of the the date of each tip species was allowed to vary most optimal trees recovered in Sheffield and according to a uniform prior stretching from Sumrall (2019a). the bottom of the time bin of the first occurrence Biogeographic models require a fully bifur- to the top of the time bin of the last occurrence. cating, time-calibrated phylogenetic tree. The The exception was Tristomiocystis globosus, the polytomies present in Sheffield and Sumrall most recently occurring taxon in the dataset, (2019a) were resolved in the Bayesian analysis which was given a fixed age of 382.7 Ma in presented herein. Overall, the topologies of order to provide a fixed time point for the both trees are largely very similar, although a other time priors. To account for the fact that few relationships changed. The monophyletic invariant characters are not collected in parsi- fi grouping uncovered in Shef eld and Sumrall mony analyses, the Mkv model (Lewis 2001) (2019a), Sphaeronitida (which also includes was implemented in the Beast2 XML via the monophyletic grouping Holocystitidae), is BEASTmasteR (Matzke and Irmis 2018). present in the fully bifurcating tree, though Among-site rate variation was modeled with relationships within sphaeronitids have a discretized gamma distribution with four cat- changed (e.g., Holocystites salmoensis is the sister egories. A relaxed clock model, with uncorre- taxon to other holocystitids, though this group lated lognormally distributed rates, was used is still monophyletic as well). The other two to model variation in the rate of morphological traditional hierarchies within Diploporita, evolution among branches. The clock rate had a Glyptosphaeritida and Asteroblastida, share flat uniform (0.00001, 2) prior, and the clock similarities in both phylogenetic reconstruc- standard deviation had a flat uniform (0, 10) tions. Glyptosphaeritida is polyphyletic in prior; this combination covers all reasonable both reconstructions and, notably, the taxon values for the average rate and its variation Eumorphocystis multiporata is sister taxon to among branches. A fossilized birth–death prior Hybocrinu nitidus, a crinoid, something (using Beast2’sBDSKYmodel)wasusedforthe uncovered in another recent phylogenetic tree prior, as it allows sampling of fossils through reconstruction (Sheffield and Sumrall 2019b). time. See Lam et al. (2018)foranexpandeddis- Asteroblastid (Asteroblastus stellatus) groups cussion of the BEASTmasteR setup. The Bayesian away from other diploporans. In Sheffield and analysis was run for 1 billion generations, sam- Sumrall (2019a), this species is the sister taxon pling every 500,000 generations, producing to edrioblastoid Eurekablastus rozhnovi;in 2000 samples. After 10% burn-in, all parameters this analysis, it is sister to E. multiporata and had estimated sample-size values above 419, lar- Hybocrinus,whileE. rozhnovi is the sister taxon. ger than the recommended minimum of 200. Rhombiferan echinoderms are uncovered as TreeAnnotator was used to summarize the polyphyletic in both analyses. Eocrinoid Rhopa- post-burn-in posterior distribution of dated phy- locystis destombesi was uncovered in both ana- logenies by generating a maximum clade cred- lyses as the taxon most distantly related to the ibility tree, used for downstream analyses. other taxa in this analysis and groups most Ancestral Range Estimation.—Probabilistic closely with G. spiralis, the out-group. inference of ancestral geographic ranges within As our goal was to obtain a fully bifurcating the phylogeny was conducted in the R package phylogeny, with more realistic divergence BioGeoBEARS (Matzke 2013). BioGeoBEARS dates than obtained from minimum ages implements, in a common likelihood frame- alone, we reanalyzed the character matrix work, the key assumptions from three

programs popular in historical biogeography: phylogeny (Supplementary File 2). This limits the dispersal–extinction–cladogenesis (DEC) the size of the state space, speeding up the com- model of Lagrange (Ree and Smith 2008); dis- putational analysis. Relative model fitwas persal–vicariance–analysis (DIVA; Ronquist measured with sample-size corrected Akaike 1997); and BayArea (Landis et al. 2013). In Bio- information criterion (AICc; Burnham and GeoBEARS, DIVA and BayArea are converted Anderson 2002). Following O’Meara et al. into a likelihood framework directly compar- (2006), AICc values were calculated using the able to DEC, and are thus referred to as DIVA- total number of taxa in the phylogeny as the LIKE and BAYAREALIKE within the package. sample size. The models allow for geographic ranges to Estimation of Type and Number of Dispersal evolve along branches in the phylogenetic Events.—The number and percentage of disper- hypothesis using range expansion (dispersal) sal events (both anagenic range expansion and and range loss (“extinction,” more accurately jump dispersal) was estimated using BSM termed “local extirpation”) processes, modeled implemented within BioGeoBEARS (Dupin with the rate parameters d and e, respectively. et al. 2017). Stochastic mapping techniques Each model makes different assumptions were first developed for discrete characters about which cladogenetic processes are like morphology and DNA (Nielsen 2002; allowed (Matzke 2013), and each model can Huelsenbeck et al. 2003; Bollback 2006). Instead be modified with an additional +j parameter of calculating the probability of each character to model the relative probability of state at each node (traditional ancestral state founder-event speciation (or jump dispersal) probabilities; Felsenstein 2003), stochastic map- during cladogenesis (Matzke 2014). This ping simulates an exact history of character mode of speciation has been found to be states across an entire tree (often represented important for many extant clades (Matzke by “painting” or “mapping” the character 2014; Dupin et al. 2017), as well as Ordovician state history onto the phylogeny). Every “sto- brachiopods and trilobites (Lam et al. 2018; chastic map” is a probabilistic sample of the Censullo and Stigall 2019; Congreve et al. 2019). possible histories of the character, conditional Although a recent critique argues that DEC on the phylogeny, the model parameters, and and DEC + j cannot be statistically compared the observed tip data. BSM implements the (Ree and Sanmartín 2018), that critique can be same method, using biogeographic models. rejected on several grounds (Klaus and Matzke The advantage of BSM over standard ancestral 2019). For example, the DEC/DEC + j statistical range probabilities is that exact event histories comparison was validated with simulation- are sampled, allowing an estimation of the inference tests in Matzke (2014), but these number and directionality of different anagen- tests were not rebutted, or even acknowledged, etic and cladogenetic events, along with uncer- by Ree and Sanmartín (2018). Instead, the tainties in these counts. The oft-used approach critique relies on peculiar behavior found of “eyeballing” the number and directionality with two tiny datasets (of 2 or 4 taxa), but of dispersal events from a plot of ancestral maximum-likelihood inferences are not range probabilities, while correlating with the expected to be reliable for such small datasets true counts, will often miss rarer or uncertain where the number of data is close to the number events, resulting in underestimation of the of inferred parameters (2–3).Similarly,the number of events. In addition, eyeball counts claimed pathological inferences (jump dispersal produce no estimate of uncertainty. The accur- at all nodes) are not observed on typical empir- acy of BSM can easily be checked, as averaging ical datasets (McDonald-Spicer et al. 2019). many BSMs will asymptotically approach the The BioGeoBEARS analysis was conducted analytically calculated ancestral range prob- without constraining the direction or timing abilities (Dupin et al. 2017). of speciation events. The maximum number Although the entire phylogeny was subject of areas that species could occupy (‘max_ran- to ancestral range estimation in BioGeoBEARS, ge_size’) was set to 2, which is the maximum we only focused the BSM analysis on the Ordo- number of areas any species occupied in the vician sections of the tree. We time-sliced the

BSM analysis to determine the amount of dis- and DIVALIKE + j). However, the most prob- persal (range expansion) and jump dispersal able ranges from BioGeoBEARS for the blas- within three time slices and to determine tozoans are identical (Supplementary File 2, whether dispersal paths changed during most probably ancestral states of DEC + j and the Ordovician Period, especially within the DIVALIKE + j). Therefore, we have focused our GOBE interval (Supplementary File 2). The first discussion on the results from the DIVALIKE + j time slice encompasses the Early to Middle model. Ordovician Tremadocian to Dapinigian ages Ancestral range estimation using DIVALIKE + j (485.4–467.3 Ma). The second time slice indicates that there are potentially several source includes just the Middle Ordovician Darriwi- regions for the species in this analysis, as lian Age (467.3–458.4 Ma), the time of the there was not a very high probability of any GOBE. The third time slice covers the Late one area as ancestral (Fig. 2A). Deep nodes in Ordovician Sandbian to Hirnantian ages the phylogeny do indicate that Baltica, Gon- (458.4–443.8 Ma), including the LOME (Fig. 2). dwana, and western Laurentia (north of the Transcontinental Arch) could be source regions for the earliest species. The geographic ranges Results of the ancestors of diploporan blastozoans Ancestral Range Estimation.—In all cases, (Fig. 2A) are highly uncertain, so these infer- the addition of the + j parameter (founder- ences should be viewed as hypotheses that event speciation) improved model fit(Table 1), can be tested by collecting specimens and geo- suggesting that anagenetic dispersal (range graphic range data near in time to the nodes in expansion) and sympatry (within-area speci- question; species with smaller ranges would ation) alone were not sufficient to fully explain tend to reduce the estimate range size of nearby the biogeographic patterns within the clade. An nodes, as well as the uncertainty. improved model fit with the addition of the + j For comparison with previous studies, bio- parameter was also observed for Ordovician geographic events were also inferred from the brachiopod and trilobite species and genera most probable ranges (Fig. 2B) under the DIVA- (Lam et al. 2018; Censullo and Stigall 2019; LIKE + j model. Dispersal was inferred by a Congreve et al. 2019). descendant most-probable range occupying a The best-fit model for the blastozoan tree new area than that of its ancestor, and vicari- presented here was DIVALIKE + j, with the ance interpreted when the descendant species DEC + j model having a slightly weaker fit. occupied subsets of the ancestor. From the The results from these analyses are very similar, tree with most likely areas (Fig. 2B), five disper- with only slight differences (e.g., in the DEC + j sal events were recovered in the first time slice, analysis, the southern Appalachian Basin has a four in the second time slice, and six in the third higher probability of being a source region for time slice. Throughout the tree, the majority of the ancestor of E. multiporata and H. nitidus; speciation is dominated by dispersal, with only Supplementary File 2, pie charts of DEC + j one vicariance event occurring within the

TABLE 1. Comparison of model fits for the Blastozoan BioGeoBEARS analysis, with the best-fit model DIVALIKE + j bolded. lnL, log-likelihood values; AIC, Akaike information criterion; AICc, corrected AIC; ΔAIC, difference between the fi ω best- t model and other models; i, Akaike weight, the relative likelihood of each model; d, dispersal rate (range expansion) along each branch within the phylogeny; e, extinction rate (range contraction) along each branch within the phylogeny; j, relative weight of jump dispersal in each model. Δ ω Model lnL AIC AICc AIC i dej DEC −84.79 173.6 174.1 33.4 4.40E-08 0.012 0.019 0 DEC + J −67.62 141.2 142.2 1 0.36 0.0012 1.00E-12 0.17 DIVALIKE −77.03 158.1 158.5 17.9 0.0001 0.01 0.008 0 DIVALIKE + J −67.11 140.2 141.2 0 0.59 0.0015 1.00E-12 0.12 BAYAREALIKE −96.12 196.2 196.7 56 5.30E-13 0.02 0.06 0 BAYAREALIKE + J −69.58 145.2 146.2 5 0.05 0.001 0.0002 0.15

Cambrian. Interestingly, this clade does not dispersal events, it is clear that Baltica was a display patterns of alternating vicariance and major source region for dispersals, as this area dispersal events (BIMES) that have been comprises more than a third of the estimated recorded in Ordovician brachiopod and trilo- dispersal events (Fig. 3). The western midconti- bite clades (Stigall et al. 2017; Lam et al. 2018; nent region within Laurentia was the second- Censullo and Stigall 2019; Congreve et al. 2019). highest source region for dispersals, with the Biogeographic Dispersal Type, Numbers, and majority of movement occurring into the south- Directionality.—Results from the Ordovician ern Appalachian Basin. Gondwana was the BSM analysis on the DIVALIKE + j models third-highest contributor to estimated dispersal indicate that range expansion (dispersal), events during the Early to early Middle founder-event speciation (jump dispersal), Ordovician, with an estimated 16.8% of events and within-area speciation were the dominant occurring from Gondwana. The majority of biogeographic events for these blastozoans Gondwanan dispersals occurred into the west- throughout the Ordovician Period (Table 2). ern midcontinent and north of the Transcontin- As the phylogeny contains only 26 species ental Arch within Laurentia. Areas that acted as within the Ordovician Period, the total number major sinks, or areas where species dispersed of events is relatively low. Across all time slices, into, include the western midcontinent, Gon- vicariance estimates were very low, with dwana, and southern Laurentia, respectively. “extinction” (meaning anagenetic range loss) Only 10% of estimated dispersal events occur estimated at 0. Within-area speciation events into Baltica, indicating this region was mainly are expected to be higher in this study due to a place out of which species dispersed. In this the large geographic areas deﬁned outside time slice, the BSM results indicate that there Laurentia (e.g., Baltica and Gondwana). was increased faunal exchange between the Among the dispersal types, founder events southern Appalachian Basin and western mid- were more than twice as common as range continent, and between Baltica and southern expansions throughout the Ordovician Laurentia. (Table 2). For this reason, we focus the follow- Speciation type changed very little during the ing discussion on dispersal patterns of the spe- Middle Ordovician Darriwilian Age, which cies in this analysis (both founder events and encompasses the GOBE (Table 2), but dispersal range expansions) through time. source and sink regions changed compared Throughout the Early to early Middle Ordo- with the ﬁrst time slice. Founder-event speci- vician, or Tremadocian to Dapingian ages, ation was still the dominant speciation mode, founder events comprised nearly half of all spe- with a slight increase in the number of estimated ciation events, and range expansions made up range expansions. Vicariance increased slightly 16% of the estimated dispersal events. Vicari- during this time, but was still generally very ance is lowest within this interval of time, and low. Within-area speciation dropped, indicating within-area speciation (sympatry) comprises sympatric speciation became less important 32% of total estimated events. Focusing on during this time due to species evolving in

TABLE 2. Biogeographic stochastic mapping results for the diploporan and other blastozoan species across the three Ordovician times. Mean values, standard deviations (SDs), and the percent of each speciation mode are shown. There were no extinction or range contractions estimated for any of the times. Time 1 is the Early to early Middle Ordovician (Tremadocian to Dapingian ages, 485.4–467.3 Ma); time 2 encompasses the Middle Ordovician Darriwilian Age, or GOBE interval (467.3–458.4 Ma); and time 3 includes the Late Ordovician Sandbian to Hirnantian ages (458.4–443.8 Ma).

Time 1 Time 2 Time 3 Speciation mode Type Mean SD Percent (%) Mean SD Percent (%) Mean SD Percent (%) Dispersal Founder events 4.75 0.93 49.84 3.96 0.49 52.59 4.32 0.63 57.37 Range expansions 1.53 0.66 16.05 1.53 0.66 20.32 1.53 0.66 20.32 Vicariance Vicariance 0.13 0.37 1.36 0.19 0.39 2.52 0.14 0.35 1.86 Within-area Speciation 3.12 0.88 32.74 1.85 0.36 24.57 1.54 0.58 20.45 Total 9.53 0.66 100 7.53 0.66 100 7.53 0.66 100

Baltica (over 45%; Fig. 3). Namely, the Cincin- nati Basin and western midcontinent were the largest source areas for dispersal events. Gon- dwana was still important, but its importance as a source for species dispersal was reduced during the Middle Ordovician (11.3% in time 2 compared with 16.8% in time 1). Instead, it acted as a sink for species (Fig. 3), with 22.2% of estimated dispersals occurring into Gondwana. Basins within Laurentia, namely the Cincinnati Basin and the western midcontinent, were also major regions for species to disperse into. During this time, there was a strong exchange of taxa between the southern Appalachian Basin and western midcontinent, and the Cincinnati Basin and Baltica (Fig. 3). The third time slice encompasses the Late Ordovician Sandbian to Hirnantian ages, which include the LOME. In this time slice, founder-event speciation events increased to their highest estimates of the three time slices, with the number of range expansions remaining unchanged from the Middle Ordovician GOBE time slice (Table 2). Vicariance and within-area speciation both decreased slightly compared with the Middle Ordovician. Areas that acted as sources for dispersal events changed little from the second time slice, but areas into which species dispersed differed greatly. Baltica remained one of the dominant areas from which the most estimated dispersals occurred, with most dispersals occurring out of the western midcontinent of Laurentia. Together, dispersal events from these two areas comprise 77% of all estimated dispersal FIGURE 3. Number of dispersal (range expansion and jump events in the third time slice. The three areas dispersal) events for the three time slices (Fig. 2)fromthe that were most important as sink regions DIVALIKE + j model. Counts of events were averaged across the 100 biogeographic stochastic mappings (BSMs) with include the Cincinnati Basin, Gondwana, and standard deviations in parentheses. Rows represent source southern Laurentia, respectively. Within the areas, columns represent destinations (or sinks). Darker Late Ordovician, estimated dispersal events shades indicate a higher frequency of dispersal events. The sum and percent of events in each row and column are between Baltica and the Cincinnati Basin given on the margins. Areas are abbreviated as follows: increased from the previous two time slices, S. Laur., southern Laurentia; W. Mid., western midcontinent; indicating an increasing number of events Gond., Gondwana; Cincin., Cincinnati Basin; N. App, northern Appalachian Basin; S. App, southern Appalachian between these regions through the entire Basin; N. TCA, north of the Transcontinental Arch. Ordovician (Fig. 3). There are also increased dispersal events between the western midcontinent and southern Laurentia and between the different regions. During this time, the source western midcontinent and the southern Appa- regions for dispersals switched to Laurentian lachian Basin during this time compared with basins, with several events still occurring from earlier time slices.

Discussion today, but there is little information available about the larval stages of Paleozoic echino- Our analyses indicate that there are still sev- derms. Some studies using more modern echi- eral questions remaining as to where these noderms, such as ophiuroids, indicate that groups originated. The most probable ranges long-distance dispersals are possible (Richards estimated from the BioGeoBEARS analysis et al. 2015), while other studies question indicate the earliest likely ancestors of the spe- whether long-distance dispersal in Paleozoic cies represented, based on their respiratory echinoderms was possible (e.g., Rozhnov structures (G. spiralis; Fig. 2), originated in Gon- 2013); however, echinoderms have extremely dwana and western North American (north of varied larval morphologies, and we cannot the Transcontinental Arch), with the earliest currently estimate whether or not diplopore- diploporan blastozoans occurring within the bearing groups would have dispersed Ordovician. Ordovician species likely also ori- similarly. ginated within Gondwana, with deep nodes Abiotic Drivers of Dispersal and Speci- in the Early Ordovician, indicating Baltica ation.—It is apparent from the reconstructed may also be a place of major evolutionary radia- ancestral areas and dispersal paths that the evo- tions for this group. Additional occurrence data lutionary history of the blastozoans was influ- across Blastozoa will allow for increased div- enced by major ocean currents and gyre ision of areas to more finely determine the ori- systems, and these paths changed through the gins for this clade. The first documented fossil Ordovician time slices defined in this study. occurrences of all of the major groups within Recovered dispersal paths from the most likely the traditional group of Diploporita (i.e., Aster- areas reconstructed from BioGeoBEARS oblastida, Sphaeronitida, and Glyptosphaeri- (Fig. 2B) and the BSM analysis (Fig. 3) were tida) appear in the same age strata in the compared with the surface ocean circulation Ordovician Prague Basin of Gondwana. model of Pohl et al. (2016b) for the Middle Because the morphology of each of these Ordovician (460 Ma; Fig. 1) under 8 times pre- groupings is disparate and diploporans are industrial atmospheric CO2 levels (PAL). polyphyletic, we hypothesize that it is possible From the Pohl et al. (2016b) analysis, there is lit- that diploporans have definitive origins earlier tle change in ocean circulation throughout the than the Ordovician. We suspect that these Ordovician; thus we use this reconstruction diplopore respiratory structures likely evolved for the entire period, although we acknowledge in the late Cambrian; this analysis may give that changing tectonic arrangements of the con- an indication as to the area in which these tinents and terranes likely influenced changes organisms might be found, as data indicate in upwelling zones and circulation patterns. that we see strong dispersal patterns from Interestingly, the majority of dispersal events Gondwana. occurred during the Early to early Middle An understanding of the limits of echino- Ordovician time slice, when the continents derm dispersal (e.g., thermal barriers) would were most widely distributed (Scotese and add immensely to this study. However, there McKerrow 1991; Fig. 4). Namely, there were is limited knowledge about fossil echinoderm several dispersal events between Gondwana larvae, especially within diplopore-bearing and Laurentia, as well as between Baltica and echinoderms, for which juvenile specimens Laurentia (Fig. 4). This finding indicates that are rarely found (Sheffield et al. 2017). Presum- distance among terranes and continents was ably, Paleozoic echinoderms dispersed during not an important factor in the dispersal and larval stages, as modern echinoderms do evolutionary history of the diploporans.

FIGURE 4. Dispersal directions for the three time slices inferred from the most likely areas occupied by ancestors in the phylogeny (bold lines, Fig. 2B) and from dispersal events recovered within the biogeographic stochastic mapping (BSM) analysis (thin lines, Fig. 3). The majority of long-distance dispersal events occur within the ﬁrst and third time slices. Dis- persal events were mainly constrained between Baltica and Laurentia and between Laurentian basins in the second time slice. Basin and area shading are the same as in Figs. 1 and 2.

Because our best-fit model incorporated jump surrounding terranes and continents, disper- dispersal (Table 1), species were likely dispersal occurred relatively unimpeded during sing among areas defined in this study through this time. Dispersal was likely mediated the use of microterranes and volcanic island among areas by the almost zonal flow of sur- arcs that were surrounding major continents face currents from Gondwana to Baltica, and (Cocks and Torsvik 2011). subsequently to Laurentia via the Iapetus Cur- The Early Ordovician, which was character- rent (Fig. 1; see also Pohl et al. 2016b:Fig.5b). ized by low atmospheric oxygen levels, gener- Significant dispersal events between Laurentia ally warm seas (Fig. 5), and a lower equator to and Baltica (Figs. 3, 4) were likely influenced pole temperature gradient due to no or few by the Iapetus Current and the anticyclonic glaciers compared with the Middle and Late surface currents between the two continents Ordovician (Trotter et al. 2008;Pohletal. in the Iapetus Ocean that are prominent 2016a; Edwards et al. 2017; Quinton et al. undermodelswith16and8PAL(Pohletal. 2018), was likely a time of few thermal ocean 2016b). barriers for blastozoan dispersal. Thus, with Among Laurentian basins, the highest num- warm seas and plenty of island arcs ber of dispersal events as recovered from the

FIGURE 5. Geochemical and evolutionary data for the Ordovician Period, with the great Ordovician biodiversiﬁcation event (GOBE) indicated by the gray horizontal bar. Blastozoan speciation events are scattered evenly through the Darriwi- lian to Katian ages, making interpretations of abiotic drivers of evolution in this dataset difﬁcult. Sea-level data are from Haq and Schutter (2008); generalized δ13C carbonate curve from Bergström et al. (2009), plotted with mercury (Hg) over total organic carbon (TOC) from Monitor Range, Nevada (gray line) from Jones et al. (2017); δ18O curve from Albanesi et al. (2019); red atmospheric CO2 curve from the GEOCARBSULF model of Krause et al. (2018); black curve of oxygen- dependent atmospheric CO2 model from Edwards et al. (2017); and blue curve of atmospheric CO2 from the COPSE biogeochemical model of Lenton et al. (2018). Brachiopod and trilobite speciation events from Lam et al. (2018). Abbreviations for carbon isotope excursions are as follows: ICE, isotope excursion; MDICE, mid-Darriwilian excursion; GICE, Guttenberg excursion; and HICE, Hirnantian excursion.

BSM analysis (Fig. 3) occur within the Early to due to the second time slice being of a much early Middle Ordovician time slice. Our shorter duration, as compared with the first finding corroborates other statistical studies of and third time slices, but the data also indicate blastozoan speciation that indicate endemism that the fewer dispersal paths recovered during among genera was depressed during the the Darriwilian Age are of higher counts Early Ordovician (Nardin and Lefebvre 2010), (Fig. 3). likely due to increased dispersal events. To Compared with the Early to early Middle date there are no models that have captured Ordovician time slice, there are several patterns surface water flow within the Laurentian epi- that differ during the Darriwilian Age. Within continental seas, but based on reconstructed the Darriwilian, it is clear that there were sev- wind vectors, surface currents likely flowed eral dispersal events between Laurentia and from the northeast to southwest (Ettensohn Baltica, namely to and from the Cincinnati 2010), with major hurricanes sweeping across Basin (Figs. 3, 4). Fewer dispersal events occur the paleocontinent from 10° to 30° north and among Laurentia, Baltica, and Gondwana, south of the equator (Jin et al. 2013). As con- and even fewer among Laurentian basins cluded in other studies that have focused on (Fig. 4). The increased number of dispersal intracratonic Laurentian dispersal events of events between Baltica and the Cincinnati marine invertebrates (Wright and Stigall 2013; Basin in the Darriwilian Age compared with Bauer and Stigall 2014; Lam and Stigall 2015; the first time slice (Fig. 3) is likely due to the Lam et al. 2018), we assume these mechanisms movement of Baltica closer to Laurentia were the primary drivers of dispersal among (Cocks and Torsvik 2011). With increased cool- basins. The lack of tectonic and thermal barriers ing (Fig. 5) and intensification of currents and that later resulted from the Taconian orogeny upwelling due to reduced temperatures and (e.g., the Sebree Trough) in the Early Ordovi- increased latitudinal temperature gradients cian, combined with strong wind and storm (Pohl et al. 2016b; Rasmussen et al. 2016; Lam activity, likely led to increased blastozoan dis- et al. 2018), the Iapetus Current (Fig. 1)was persal events among areas and decreased likely a major factor facilitating trans-Iapetus endemism during this time. dispersal. On the southern margin of Laurentia, The second time slice in our analysis corre- the Taconian orogeny Blountian tectophase sponds to the Darriwilian Age and the GOBE was in full swing during this time (Ettensohn interval (Fig. 5), a time when oceans cooled 2010). Our data indicate that limited dispersal with the growth of continental land glaciers among Laurentian basins may have been over Gondwana (Quinton et al. 2015; Pohl caused by increased tectonic activity, which et al. 2016a; Edwards et al. 2018; Albanesi would have led to increased cool-water influx et al. 2019). During this time, ocean circulation into the craton through the Sebree Trough may have vigorously increased as the tempera- (Young et al. 2015) and the addition of physical ture gradients from the equator to poles barriers blocking species dispersal. increased and thus aided in dispersal dynamics The triggers of the GOBE have been dis- of benthic marine invertebrates during their cussed in great detail in previous works, larval phases (Rasmussen et al. 2016; Lam including increased atmospheric oxygen levels, et al. 2018; Stigall et al. 2019), in part leading a cooling climate and ocean, and cessation of to the continued low endemicity of blastozoans anoxic events, coinciding in part with increased through the Darriwilian Age (Nardin and diversity among microfossil and invertebrate Lefebvre 2010). This interval of our study is clades (reviewed in Stigall et al. 2019). From characterized by a decreased number of disper- our new analyses on this blastozoan echino- sal events as interpreted from the most likely derm phylogeny, it is clear that these Earth areas reconstructed within BioGeoBEARS system changes may not have affected diplo- (Fig. 2) and the BSM analysis (Fig. 3), but only porans and other blastozoans as they did by 0.79 compared with the first time slice and other shelly marine invertebrates, or perhaps 0.36 compared with the third time slice. The global cooling and the growth of Gondwanan reduced number of dispersal events may be glaciers (Pohl et al. 2016a) negatively affected

them. Our data indicate slightly reduced and et al. 2008; Finnegan et al. 2011; Melchin et al. limited dispersal events and paths during the 2013; Pohl et al. 2016a) that all culminated in GOBE interval, compared with the Early Ordo- the LOME in the latest Katian and Hirnantian vician, along with low endemism (Nardin and ages. Throughout this time slice, especially in Lefebvre 2010). Diversity curves for the blas- the Sandbian and Katian, blastozoan species tozoans at the genus level in other studies do exhibit speciation events regardless of these suggest an increase in diversity during the Dar- environmental perturbations, until the time riwilian (Nardin and Lefebvre 2010). Because before the LOME (Fig. 5). Interestingly, there of increased diversity and low endemism, we is one speciation event that occurs between would expect to see increased dispersal events the two major Hg/total organic carbon (TOC) among several basins during this time. We sug- enrichments (Jones et al. 2017; Fig. 5). Modeling gest additional analyses of blastozoan diversity studies have indicated that emplacement and and endemism at the species level be con- subsequent weathering of a LIP could lead to ducted before trying to further explore patterns 5°C cooling within 2 Myr of emplacement and drivers of blastozoan speciation across the within the Late Ordovician Katian Age GOBE interval. Other echinoderm studies indi- (Lefebvre et al. 2010). If gradual cooling does cate that members of this large and diverse lead to increased speciation, as other evolution- group did obtain increased richness and diver- ary studies during times of Cenozoic global sity during the GOBE (e.g., Wright and Toom cooling have proposed (e.g., Fraass et al. 2015; 2017; Cole 2019), hinting that the blastozoans Davis et al. 2016; Baarli et al. 2017; Lam and may have followed a similar trend. Leckie 2020; A. R. Lam and R. M. Leckie During the Late Ordovician time slice, there unpublished data), we would predict speci- is again an increased number of dispersal ation events occurring within 2 Myr of LIP events recovered from the BioGeoBEARS and activity. Indeed, we do see this occur in this BSM analyses. However, dispersals from the blastozoan phylogeny and for the brachiopods Late Ordovician BSM analysis are still less that exhibit vicariance events (Fig. 5) after the than those recovered for the Early to early Mid- first Mg/TOC pulse in the latest Katian. We dle Ordovician time slice (Fig. 3). During this caution that we have limited data on which to interval, species dispersals among Laurentia, base this hypothesis, but propose that add- Gondwana, and Baltica are prevalent, with sev- itional data and studies with more refined eral dispersal events apparent between Gon- stratigraphic control on species temporal dwana and Laurentia (Fig. 4). The highest ranges and occurrences could reveal more number of dispersals between Baltica and the interesting evolutionary patterns in response Cincinnati Basin occur during this time to the Late Ordovician LIP events. (Fig. 3), indicating increased connectivity It is clear from the phylogenetic hypothesis between these regions through the entire Ordo- of blastozoans presented here that this group vician Period as these continents moved closer was hit hard during the first pulse of the together. Interestingly, the majority of disper- LOME at the Katian/Hirnantian boundary, sals into Laurentian basins occur into areas with several species going extinct just before that are located on the southern margin. This or at the boundary (Fig. 2). However, one may be due to the deposition of warm-water grouping of diploporans, the holocystitids, facies that resumed in the Katian Age (Etten- continues across the LOME into the Silurian, sohn et al. 2002), providing more niche space with reconstructed ancestral ranges indicating within these regions for species. strong affinities to the Cincinnati Basin Several Earth system changes occurred dur- (Fig. 2A). Further work should explore the ing the Late Ordovician, namely the possible trends and drivers of extinction selectivity emplacement of a LIP (Jones et al. 2017) in the across the LOME in this particular group. late Katian to Hirnantian ages (Fig. 5), Comparison of Dispersal Paths and Speciation increased global cooling and the growth of gla- Types.—Few other studies have utilized BioGeo- ciers in the Katian, then subsequent glacial BEARS to reconstruct ancestral relationships melting (Saltzman and Young 2005; Trotter and infer patterns of speciation and dispersal,

but here we compare our results with those of Ordovician, trilobite dispersal events occur Lam et al. (2018) and Congreve et al. (2019). among most Laurentian basins, with no prefer- Our results indicate that speciation events in ence for direction or any one basin (Lam et al. the Ordovician were dominated by dispersal, 2018). The Early to early Middle Ordovician a pattern that is similar to brachiopod clades dispersal paths for the blastozoans are very in the Lam et al. (2018) study. Speciation events similar, with rampant paths recovered among for the diploporans and other blastozoan spe- all Laurentian basins with no perceivable pref- cies are scattered throughout the Ordovician, erence for direction. In Lam et al. (2018), Late whereas brachiopod speciation events are clus- Ordovician Laurentian dispersal and vicari- tered within the Late Ordovician, and trilobite ance events for brachiopods and trilobites speciation events are clustered within the Floian retain a random pattern among the Laurentian Age and Dapingian to Darriwilian ages, which southern and western basins, with a directional- are times of global cooling (Fig. 5). ity preference from interior basins into northern The three groups (blastozoans, brachiopods, and southern basins. The Late Ordovician blas- and trilobites) converge in their similarity of tozoan dispersal paths are similar, except dis- type of speciation through the Ordovician. persal into the southern Laurentian Basin Among all the models for the groups, models (Fig. 4) occurs bidirectionally between basins. that incorporated the + j parameter improved In summary, there are several differences model fit, suggesting that jump dispersal was and similarities among dispersal paths across a speciation mode utilized by several marine clades during the Ordovician. Comparisons invertebrates. Thus, the finding from our aremadedifficult across studies by the in- study and those of Lam et al. (2018) and Con- consistent delineation of basins and areas as greve et al. (2019) support the hypothesis of Sti- restricted by the occurrences of species and the gall et al. (2019) that several volcanic island arcs time slicing of dispersal paths discussed. How- allowed for increased long-distance dispersal ever, it is clear that jump dispersal improves events and likely primed the GOBE event that biogeographic model fit for invertebrate clades, occurred in the Darriwilian Age. Additional and the exchange of taxa between Baltica and BioGeoBEARS results from Bauer (2020) for Laurentia was dominant throughout the Ordo- echinoderm taxa also indicate models with vician Period. the + j parameter fit the data best. Therefore, jump dispersal may be a prevalent mode of spe- Conclusions and Future Work ciation during several times in the Paleozoic. Lam et al. (2018) and Congreve et al. (2019) This study is the first to infer Ordovician also recovered several dispersal events between diploporan blastozoan speciation and dispersal Laurentia and Baltica from the Dapingian to events within a rigorous statistically informed Sandbian ages for trilobites and brachiopods. phylogenetic framework. Probabilistic infer- Interestingly, the majority of the Lam et al. ence of ancestral ranges was conducted within (2018) dispersal paths are from Laurentia to Bal- the R package BioGeoBEARS to determine the tica, whereas those reconstructed in this analysis origin for these organisms and most likely are bidirectional between these areas (Figs. 3, 4). mode of speciation through time. The number For brachiopods and trilobites, there are a num- and percent of dispersal events was estimated ber of dispersal events, mainly from Laurentia to using BSM to determine how dispersal paths Gondwana, during the Middle Ordovician changed across three time slices through the (Lam et al. 2018) and between the two areas Ordovician. The first time slice includes the (Congreve et al. 2019). This study indicates dis- Early to early Middle Ordovician; the Darriwi- persals of these blastozoan species between lian Age time slice includes the GOBE; and the Laurentia and Gondwana were more restricted Late Ordovician time slice includes several during this interval but still prevalent (Fig. 4). Earth system perturbations and the LOME. There are several differences and similarities The results of the BioGeoBEARS analysis when Ordovician dispersal paths are compared indicate that all models that included the + j within Laurentia across clades. In the Middle parameter for jump dispersal improved model

fit, with the best-fit model being DIVALIKE + j. invertebrate groups. A larger dataset of blas- This suggests that jump dispersal was an tozoan taxa with additional and broader occur- important speciation mode for these species. rence data and improved stratigraphic and From the DIVALIKE + j model, there are sev- temporal ranges will help reveal further drivers eral potential source regions for the earliest of speciation and dispersal during the early ancestors of the diploporans, with true diplo- Paleozoic. porans appearing in the Early Ordovician and We acknowledge that a geographic bias in likely originating in either Baltica or Gon- sampling toward Baltica and Laurentia exists dwana, potentially during the late Cambrian. across many invertebrate taxa, with Gondwana Results from the BSM analysis indicate that and other paleocontinents being less broadly founder-event speciation accounted for nearly explored (Miller 2000; Tarver et al. 2007;Sumrall half of all speciation events within all three and Zamora 2011;Lefebvreetal.2013). This time slices. biases overall interpretations of paleoecological Directionality of dispersal events was and biogeographic trends, as Laurentia and inferred from both range expansion and jump- South China were primarily situated in more dispersal speciation. Within the Early to early tropical, carbonate regimes, whereas Gondwa- Middle Ordovician time slice, the highest num- nan depositional environments were more silici- ber of dispersal events was recovered, with sev- clastic during the Ordovician. More accurate eral occurring among Laurentia, Baltica, and paleobiogeographic trends will be assessed Gondwana. Several events were also recovered with better global sampling, as new fossil species among Laurentian basins. The Middle Ordovi- incorporated into phylogenetically informed cian time slice, characterized by the GOBE, paleobiogeographic studies can drastically includes the least amount of recovered disper- change interpretations of diversity and bio- sal events, but with important dispersal events geography (Lefebvre et al. 2005; Sumrall et al. between Baltica and the Cincinnati Basin. The 2015; Zamora et al. 2016). Future work should Late Ordovician again shows an increased focus on sampling more global occurrences of number of dispersals among Laurentia, Baltica, blastozoan echinoderms to be included in and Gondwana, with dispersals most prevalent future biogeographic studies, so that we on the southern edge of the Laurentian paleo- might be able to better assess the abiotic factors continent. These findings indicate that distance driving Paleozoic echinoderm speciation and did not impede dispersal, and species likely uti- biogeography. lized the major current and gyre systems that flowed between continents. Intracontinental Acknowledgments Laurentian dispersal events were likely mediated We would like to thank J. E. Bauer and by surface currents and strong storm activity, and M. R. Limbeck for reading earlier versions of perhaps the lack of tectonically emplaced thermal this article. We thank B. Deline and an anonym- and physical barriers that did not develop until ous reviewer for critical comments and sugges- the Middle Ordovician. tions that greatly strengthened this contribution. Compared with geochemical data and model A.R.L. was supported by a Cushman Foundation results for the Ordovician, blastozoan dispersal for Foraminiferal Research Johanna M. Resig and jump dispersal do not cluster during times Foraminiferal Research Fellowship and the of global cooling or atmospheric oxygenation, Binghamton University Presidential Diversity as has been found for brachiopods and trilo- Postdoctoral Fellowship. S.L.S. was supported bites. This indicates that the blastozoans may by the Paleontological Society Arthur James have had different environmental tolerances Boucot Research Grant. N.J.M.’s development than other marine invertebrates and did not of BioGeoBEARS and BEASTmasteR were sup- respond similarly to abiotic factors. Further ported by the National Institute for Mathemat- analyses may also help to understand how bio- ical and Biological Synthesis, an institute geographic patterns and oxygen levels may sponsored by the National Science Foundation have played different roles in blastozoan evolu- (NSF), the U.S. Department of Homeland tionary patterns, as compared with other Security, and the U.S. Department of

Agriculture through NSF award no. Brenchley, P. J. 1995. Environmental changes associated with the “first strike” of the Late Ordovician mass extinction. Modern EFJ0832858, with additional support from the Geology 20:69–72. University of Tennessee, Knoxville. N.J.M. was Brenchley, P. J., and J. D. Marshall. 1999. Relative timing of also funded by the Australian Research Council’s critical events during the late Ordovician mass extinction—new data from Oslo. Acta-Universitatis Carolinae-Geologica 43:187– Discovery Early Career Researcher award no. 190. DE150101773, and by the Australian National Brenchley, P. J., J. D. Marshall, G. A. F. Carden, D. B. R. Robertson, University. He is currently supported by the Uni- D. G. F. Long, T. Meidla, L. Hints, and T. F. Anderson. 1994. Bathymetric and isotopic evidence for a short-lived Late Ordovi- versity of Auckland and New Zealand Marsden cian glaciation in a greenhouse period. Geology 22:295–298. Grants 16–UOA–277 and 18–UOA–034. Fund- Burnham, K. P., and D. R. Anderson. 2002. Model selection and ing for publication was kindly provided by multimodel inference: a practical information-theoretical approach. Springer-Verlag, New York. the University of South Florida Libraries. Sup- Censullo, S. M., and A. L. Stigall. 2019. Did alternating dispersal plementary Files 1 and 2 can be found at and vicariance drive biodiversity increase during the Great Ordo- https://doi.org/10.5061/dryad.4tmpg4f6j. vician Biodiversification Event? A phylogenetic test using brachiopods. Geological Society of America Abstracts with Programs 51, doi: 10.1130/abs/2019AM-333129. Clausen, S. 2004. New early Cambrian eocrinoids from the Iberian Chains (NE Spain) and their role in nonreefal benthic communi- Literature Cited ties. Eclogae Geologicae Helveiae 97:371–379. Albanesi, G. L., C. R. Barnes, J. A. Trotter, I. S. Williams, and Clausen, S., and A. B. Smith. 2005. Palaeoanatomy and biological S. M. Bergström. 2019. Comparative Lower–Middle Ordovician affinities of a Cambrian deuterostome. Nature 438:351–354. conodont oxygen isotope palaeothermometry of the Argentine Clausen, S., and A. B. Smith. 2008. Stem structure and evolution in Precordillera and Laurentian margins. Palaeogeography, Palaeo- the earliest pelmatozoan echinoderms. Journal of Paleontology climatology, Palaeoecology. doi: 10.1016/j.palaeo.2019.03.016. 82:737–748. Amberg, C. E. A, T. Collart, W. Salenbien, L. M. Egger, A. Munnecke, Cocks, L. R. M., and T. H. Torsvik. 2011. The Palaeozoic geography A. T. Nielsen, C. Monnet, Ø. Hammer, and T. R. AVandenbroucke. of Laurentia and western Laurussia: a stable craton with mobile 2016. The nature of Ordovician limestone-marl alternations in the margins. Earth-Science Reviews 106:1–51. Oslo-Asker District (Norway): witnesses of primary glacio-eustasy Cole, S. R. 2019. Phylogeny and evolutionary history of diploba- or diagenetic rhythms? Scientific Reports 6:18787. thrid crinoids (Echinodermata). Palaeontology 62:357–373. Amsden, T. W. 1974. Late Ordovician and Early Silurian articulate Congreve, C. R., A. Z. Krug, and M. E. Patzkowsky. 2019. Evolu- brachiopods from Oklahoma, southwestern Illinois, and eastern tionary and biogeographical shifts in response to the Late Ordo- Missouri. Oklahoma Geological Survey Bulletin 119:1–154p. vician mass extinction. Palaeontology 62:267–285. Amsden, T. W. 1986. Part I. Paleoenvironment of the Keel- Crowell, J. C. 1999. Pre-Mesozoic ice ages: their bearing on under- Edgewood oolitic province and the Hirnantian strata of Europe, standing the climate system. Geological Society of America USSR, and China. Oklahoma Geological Survey Bulletin 139:1–55. Memoir 192. Baarli, B., M. C. D. Malay, A. Santos, M. E. Johnson, C. M. Silva, Crowley, T. J., and S. K. Baum. 1991. Toward reconciliation of Late ∼ J. Meco, M. Cachão, and E. J. Mayoral. 2017. Miocene to Pleisto- Ordovician ( 440 Ma) glaciation with very high CO2 levels. Jour- cene transatlantic dispersal of Ceratoconcha coral-dwelling nal of Geophysical Research: Atmospheres 96:22597–22610. barnacles and North Atlantic island biogeography. Palaeogeog- Dabard, M.-P., A. Loi, F. Paris, J.-F. Ghienne, M. Pistis, and M. Vidal. raphy, Palaeoclimatology, Palaeoecology 468:520–528. 2015. Sea-level curve for the Middle to early Late Ordovician in Barrick, J. E. 1986. Conodont faunas of the Keel and Cason Forma- the Armorican Massif (western France): icehouse third-order tions. Oklahoma Geological Survey Bulletin 139:57–89. glacio-eustatic cycles. Palaeogeography, Palaeoclimatology, Bauer, J. E. 2020. Paleobiogeography, paleoecology, diversity, and Palaeoecology 436:96–111. speciation patterns in the Eublastoidea (Blastozoa: Echinoder- Davis, K. E., J. Hill, T. I. Astrop, and M. A. Wills. 2016. Global cool- mata). Paleobiology. doi: 10.1017/pab.2020.27. ing as a driver of diversification in a major marine clade. Nature Bauer, J. E., and A. L. Stigall. 2014. Phylogenetic paleobiogeogra- Communications 7:13003. phy of Late Ordovician Laurentian brachiopods. Estonian Journal Deline, B. 2015. Quantifying morphological diversity in of Earth Sciences 63:189–194. Early Paleozoic Echinoderms. Pp. 45–48 in S. Zamora and Bergström, S. M., X. Chen, J. C. Gutierrez-Marco, and A. Dronov. I. Rábano, eds. Progress in echinoderm palaeobiology. Cuademos 2009. The new chronostratigraphic classification of the Ordovi- del Museo Geominero 19. Instituto Geológico y Minero de España, cian system and its relations to major regional series and stages Madrid. and to δ13C chemostratigraphy. Lethaia 42:97–107. Deline, B., and J. R. Thomka. 2017. The role of preservation on the Beuf, S., B. Biju-Duval, O. de Charpal, P. Rognon, O. Gariel, and quantification of morphology and patterns of disparity with A. Bennacef. 1971. Les Grés du Paléozoique inférieur au Sahara: Paleozoic echinoderms. Journal of Paleontology 91:618–632. sédimentation et discontinuités, évolution structurale d’un cra- Deline, B. J. R. Thompson, N. S. Smith, S. Zamora, I. A. Rahman, S. ton. Publications de l’Institut Français du Pe´trole, Editions Tech- L. Sheffield, W. I. Ausich, T. W. Kammer, and C. D. Sumrall. nip 18:1–464. 2020. Evolution and development at the origin of a phylum. Cur- Bollback, J. 2006. SIMMAP: Stochastic character mapping of dis- rent Biology 30. doi: 10.1016/j.cub.2020.02.054. crete traits on phylogenies. BMC Bioinformatics 7:88. Dickson, J. A. D. 2004. Echinoderm skeletal preservation: Bouckaert, R., J. Heled, D. Kühnert, T. Vaughan, C.-H. Wu, D. Xie, calcite-aragonite seas and the Mg/Ca ratio of Phanerozoic M. A. Suchard, A. Rambaut, and A. J. Drummond. 2014. BEAST oceans. Journal of Sedimentary Research 74:355–365. 2: a software platform for Bayesian evolutionary analysis. PLoS Dupin, J., N. J. Matzke, T. Särkinen, S. Knapp, R. G. Olmstead, Computational Biology 10:e1003537. L. Bohs, and S. D. Smith. 2017. Bayesian estimation of the global Branson, E. R., and R. E. Peck. 1940. A new cystoid from the Ordo- biogeographical history of the Solanaceae. Journal of Biogeog- vician of Oklahoma. Journal of Paleontology 14:89–92. raphy 44:887–899.

Edwards, C. T., M. R. Saltzman, D. L. Royer, and D. A. Fike. 2017. integration of faunal and palaeomagnetic constraints. Palaeo- Oxygenation as a driver of the Great Ordovician Biodiversiﬁca- geography, Palaeoclimatology, Palaeoecology 121:297–312. tion Event. Nature Geoscience 10:925–929. Herrmann, A. D., B. J. Haupt, M. E. Patzkowsky, D. Seidov, and R. Edwards, C. T., C. M. Jones, and D. A. Fike. 2018. Oxygen isotope L. Slingerland. 2004. Response of the Late Ordovician paleocea- (δ18O) trends measured from Early–Middle Ordovician conodont nography to changes in sea level, continental drift, and atmos-

apatite using secondary ion mass spectrometry (SIMS): implica- pheric pCO2: potential causes for long-term cooling and tions for ocean paleothermometry studies. Annual meeting of glaciation. Palaeogeography, Palaeoclimatology, Palaeoecology the International Geoscience Programme Project 653: Onset of 210:385–401. the Great Ordovician Biodiversification Event 3, p. 31. Holland, S. M., and M. E. Patzkowsky. 1997. Distal orogenic effects Elias, R. J. 1983. Middle and Late Ordovician solitary rugose corals on peripheral bulge sedimentation: Middle and Upper Ordovi- of the Cincinnati Arch region. U.S. Geological Survey Profes- cian of the Nashville Dome. Journal of Sedimentary Research sional Paper 1066-N:I–III. 67:250–263. Ettensohn, F. R. 2004. Modeling the nature and development of Huelsenbeck, J. P., R. Nielsen, and J. P. Bollback. 2003. Stochastic major Paleozoic clastic wedges in the Appalachian Basin, USA. mapping of morphological characters. Systematic Biology Journal of Geodynamics 37:657–681. 52:131–158. Ettensohn, F. R. 2010. Origin of Late Ordovician (mid-Mohawkian) Hutton, D. H. W., and F. C. Murphy. 1987. The Silurian of the temperate-water conditions on southeastern Laurentia: glacial or Southern Uplands and Ireland as a successor basin to the tectonic. The Ordovician earth system. Geological Society of end-Ordovician closure of Iapetus. Journal of the Geological America Special Paper 466:163–175. Society 144:765–772. Ettensohn, F. R., C. R. Barnes, and S. H. Williams. 1991. Flexural Jin, J., D. A. T. Harper, L. R. M. Cocks, P. J. A. McCausland, interpretation of relationships between Ordovician tectonism C. M. Ø. Rasmussen, and P.M. Sheehan. 2013. Precisely locating and stratigraphic sequences, central and southern Appalachians, the Ordovician equator in Laurentia. Geology 41:107–110. USA. Pp. 213–224 in J. D. Witman and K. Roy, eds. Advances in Jones, D. S., A. M. Martini, D. A. Fike, and K. Kaiho. 2017. A vol- Ordovician geology. Geological Survey of Canada Paper 90-9. canic trigger for the Late Ordovician mass extinction? Mercury Ettensohn, F. R., J. C. Hohman, M. A. Kulp, and N. Rast. 2002. Evi- data from South China and Laurentia. Geology 45:631–634. dence and implications of possible far-field responses to Taconian Keith, B. D. 1989. Regional facies of the Upper Ordovician Series of orogeny: Middle–Late Ordovician Lexington Platform and Sebree eastern North America. The Trenton Group (Upper Ordovician Trough, east-central United States. Southeastern Geology 41:1–36. Series) of Eastern North America. American Association of Pet- Eyles, N. 1993. Earth’s glacial record and its tectonic setting. Earth- roleum Geologists Studies in Geology 26:1–16. Science Reviews 35:1–248. Klaus, K., N. J. Matzke. 2019. Statistical comparison of trait- Felsenstein, J. 2003. Inferring phylogenies. Oxford University dependent biogeographical models indicates that podocarpaceae Press, Oxford. dispersal is influenced by both seed cone traits and geographical Finnegan, S., K. Bergmann, J. M. Eiler, D. S. Jones, D. A. Fike, distance. Systematic Biology 69:61–75. I. Eisenman, N. C. Hughes, A. K. Tripati, and W. W. Fischer. Kolata, D. R., W. D. Huff, and S. M. Bergstro¨m. 2001. The Ordovi- 2011. The magnitude and duration of Late Ordovician–Early cian Sebree trough: an oceanic passage to the Midcontinent Silurian glaciation. Science 331:903–906. United States. Geological Society of America Bulletin 113:1067– Finnegan,S.,N.A.Heim,S.E.Peters,andW.W.Fischer.2012. Climate 1078. change and the selective signature of the Late Ordovician mass Krause, A. J., B. J. W. Mills, S. Zhang, N. J. Planavsky, T. M. Lenton, extinction. Proceedings of the National Academy of Sciences and S. W. Poulton. 2018. Stepwise oxygenation of the Paleozoic USA 109:6829–6834. atmosphere. Nature Communications 9:4081. Finnegan, S. N., C. M. Ø. Rasmussen, and D. A. T. Harper. 2016. Kröger, B., and K. Lintulaakso. 2017. RNames, a stratigraphical Biogeographic and bathymetric determinants of brachiopod database designed for the statistical analysis of fossil occurrences. extinction and survival during the Late Ordovician mass Palaeontologia Electronica 20:20.1.1T. extinction. Proceedings of the Royal Society of London B Lam, A. R., and R. M. Leckie. 2020. Late Neogene and Quaternary 283:201600007. diversity and taxonomy of subtropical to temperate planktic for- Fitton, J. G., and D. J. Hughes. 1970. Volcanism and plate tectonics aminifera across the Kuroshio Current Extension, northwest in the British Ordovician. Earth and Planetary Science Letters Pacific Ocean. Micropaleontology 66:177–268. 8:223–228. Lam, A. R., and A. L. Stigall. 2015. Pathways and mechanisms Fortey, R. A. 1984. Global earlier Ordovician transgressions and of Late Ordovician (Katian) faunal migrations of Laurentia and regressions and their biological implications. Pp. 37–50 in D. L. Baltica. Estonian Journal of Earth Sciences 64:62–67. Bruton, ed. Aspects of the Ordovician system. Universitetsforla- Lam, A. R., A. L. Stigall, and N. J. Matzke. 2018. Dispersal in the get Oslo, Oslo. Ordovician: speciation patterns and paleobiogeographic analyses Fraass, A. J., D. C. Kelly, and S. E. Peters. 2015. Macroevolutionary of brachiopods and trilobites. Palaeogeography, Palaeoclimat- history of the planktic foraminifera. Annual Review of Earth and ology, Palaeoecology 489:147–165. Planetary Sciences 43:139–166. Lamsdell, J. C., C. R. Congreve, M. J. Hopkins, A. Z. Krug, and M. E. Glen, R. A., J. L. Walshe, L. M. Barron, and J. J. Watkins. 1998. Ordo- Patzkowsky. 2017. Phylogenetic palaeoecology: tree-thinking vician convergent-margin volcanism and tectonism in the Lach- and ecology in deep time. Trends in Ecology and Evolution lan sector of east Gondwana. Geology 26:751–754. 32:452–463. Hambrey, M. J. 1985. The Late Ordovician—Early Silurian glacial Landis, M., N. J. Matzke, B. R. Moore, and J. P. Huelsenbeck. 2013. period. Palaeogeography, Palaeoclimatology, Palaeoecology Bayesian analysis of biogeography when the number of areas is 51:273–289. large. Systematic Biology 62:789–804. Haq, B. U., and S. R. Schutter. 2008. A chronology of Paleozoic sea- Lefebvre, B. 2007. Early Palaeozoic palaeobiogeography and level changes. Science 322:64–68. palaeoecology of stylophoran echinoderms. Palaeogeography, Harper, D. A. T. 2006. The Ordovician biodiversification: setting an Palaeoclimatology, Palaeoecology 245:156–199. agenda for marine life. Palaeogeography, Palaeoclimatology, Lefebvre, B., M. Ghobadipour, and E. Nardin. 2005. Ordovician Palaeoecology 232:148–166. echinoderms from the Tabas and Damghan regions, Iran: palaeo- Harper, D. A. T., C. Mac Niocaill, and S. H. Williams. 1996. The biogeographical implications. Bulletin de la Société géologique de palaeogeography of early Ordovician Iapetus terranes: an France 176:231–242.

Lefebvre, V., T. Servais, L. François, and O. Averbuch. 2010. Did Pedersen, R. B., D. L. Bruton, and H. Furnes. 1992. Ordovician fau- a Katian large igneous province trigger the Late Ordovician nas, island arcs and ophiolites in the Scandinavian Caledonides. glaciation? A hypothesis tested with a carbon cycle model. Terra Nova 4:217–222. Palaeogeography, Palaeoclimatology, Palaeoecology 296:310– Pohl, A., Y. Donnadieu, G. Le Hir, J.-B. Ladant, C. Dumas, 319. J. Alvarez-Solas, and T. R. A Vandenbroucke. 2016a. Glacial Lefebvre, B., C. D. Sumrall, R. A. Shroat-Lewis, M. Reich, G. D. onset predated Late Ordovician climate cooling. Paleoceanogra- Webster, A. W. Hunter, E. Nardin, S. V. Rozhnov, T. E. Guens- phy 31:800–821. berg, and A. Touzeau. 2013. Palaeobiogeography of Ordovician Pohl, A., E. Nardin, T. R. A. Vandenbroucke, and Y. Donnadieu. echinoderms. Geological Society of London Memoir 38:173–198. 2016b. High dependence of Ordovician ocean surface circulation

Lenton, T. M., S. J. Daines, and B. J. W. Mills. 2018. COPSE on atmospheric CO2 levels. Palaeogeography, Palaeoclimatology, reloaded: an improved model of biogeochemical cycling over Palaeoecology 458:39–51. Phanerozoic time. Earth-Science Reviews 178:1–28. Pohl, A., D. A. T. Harper, Y. Donnadieu, G. Le Hir, E. Nardin, and Lewis, P. O. 2001. A likelihood approach to estimating phylogeny T. Servais. 2018. Possible patterns of marine primary productiv- from discrete morphological character data. Systematic Biology ity during the Great Ordovician Biodiversiﬁcation Event. Lethaia 50:913–925. 51:187–197. Liljeroth, M., D. A. T. Harper, H. Carlisle, and A. T. Nielsen. 2017. Pope, M. C., and J. B. Steffen. 2003. Widespread, prolonged late Ordovician rhynchonelliformean brachiopods from Co. Water- Middle to Late Ordovician upwelling in North America: a ford, SE Ireland: Palaeobiogeography of the Leinster Terrane. proxy record of glaciation? Geology 31:63–66. Wiley, Hoboken, N.J. Poussart, P. F., A. J. Weaver, and C. R. Barnes. 1999. Late Ordovi-

Matzke, N. J. 2013. Probabilistic historical biogeography: new mod- cian glaciation under high atmospheric CO2: a coupled model els for founder-event speciation, imperfect detection, and fossils analysis. Paleoceanography 14:542–558. allow improved accuracy and model-testing. Frontiers in Bio- Pruss, S. B., Finnegan, W. W. Fischer, and A. H. Knoll. 2010. Carbo- geography 5:242–248. nates in skeleton-poor seas: new insights from Cambrian and Matzke, N. J. 2014. Model selection in historical biogeography Ordovician strata of Laurentia. Palaios 25:73–84. reveals that founder-event speciation is a crucial process in island Quinton, P. C., I. G. Percival, Y. Zhen, and K. G. Macleod. 2015. clades. Systematic Biology 63:951–970. Ordovician temperature trends: constraints from δ18O analysis of Matzke, N. J. 2019. BEASTMasteR code archive. https://github. conodonts from New South Wales, Australia. Stratigraphy 12:61–66. com/nmatzke/BEASTmasteR, accessed 12 December 2019. Quinton, P. C., S. Law, K. G. Macleod, A. D. Herrmann, J. T. Haynes, Matzke, N. J., and R. B. Irmis. 2018. Including autapomorphies in and S. A. Leslie. 2017. Testing the early Late Ordovician cool- paleontological datasets is important for tip-dating with clocklike water hypothesis with oxygen isotopes from conodont apatite. data, but not with non-clock data. PeerJ 6:e4553. Geological Magazine 155:1727–1741. Matzke, N. J., and A. Wright. 2016. Inferring node dates from tip Quinton, P. C., L. Speir, J. Miller, R. Ethington, and K. G. MacLeod. dates in fossil Canidae: the importance of tree priors. Biology Let- 2018. Extreme heat in the Early Ordovician. Palaios 33:353–360. ters 12:20160328. Rahman, I. A., and S. Zamora. 2009. The oldest cinctan caproid McDonald-Spicer, C., N. J. Knerr, F. Encinas-Viso, and A. N. (stem-group Echinodermata), and the evolution of the water Schmidt-Lebuhn. 2019. Big data for a large clade: bioregionaliza- vascular system. Zoological Journal of the Linnean Society tion and ancestral range estimation in the daisy family (Astera- 157:420–432. ceae). Journal of Biogeography 46:255–267. Rasmussen, C. M. Ø., and D. A. T. Harper. 2011. Did the amalgam- Melchin, M. J., C. E. Mitchell, C. Holmden, and P. Štorch. 2013. ation of continents drive the end Ordovician mass extinctions?. Environmental changes in the Late Ordovician–early Silurian: Palaeogeography, Palaeoclimatology, Palaeoecology 311:48–62. review and new insights from black shales and nitrogen isotopes. Rasmussen, C. M. Ø., C. V. Ullmann, K. G. Jakobsen, A. Lindskog, GSA Bulletin 125:1635–1670. J. Hansen, T. Hansen, M. E. Eriksson, A. Dronov, R. Frei, C. Korte, Miller, A. I. 1997. Dissecting global diversity patterns: examples A. T. Nielsen, and D. A. T. Harper. 2016. Onset of main Phanero- from the Ordovician Radiation. Annual Review of Ecology and zoic marine radiation sparked by emerging Mid Ordovician ice- Systematics 28:85–104. house. Scientific Reports 6:18884. Miller, A. I. 2000. Conversations about Phanerozoic global diver- Ree, R. H., and I. Sanmartín. 2018. Conceptual and statistical pro- sity. Paleobiology 26:53–73. blems with the DEC + J model of founder-event speciation and Mohibullah, M., M. Williams, T. R. A. Vandenbroucke, K. Sabbe, its comparison with DEC via model selection. Journal of Biogeog- and J. A. Zalasiewicz. 2012. Marine ostracod provinciality in raphy 45:741–774. the Late Ordovician of paleocontinental Laurentia and its Ree R. H., and S. A. Smith. 2008. Maximum likelihood inference of environmental and geographic expression. PLoS ONE 7: geographic range evolution by dispersal, local extinction, and e41682. cladogenesis. Systematic Biology 57:4–14. Nardin, E., and B. Lefebvre. 2010. Unravelling extrinsic and intrin- Richards, V. P., M. B. DeBiasse, and M. S. Shivii. 2015. Genetic evi- sic factors of the early Palaeozoic diversification of blastozoan dence supports larval retention in the western Caribbean for an echinoderms. Palaeogeography, Palaeoclimatology, Palaeoecol- invertebrate with high dispersal capability (Ophiothrix suensonii: ogy 294:142–160. Echinodermata, Ophiuroidea). Coral Reefs 34:313–325. Nielsen, R. 2002. Mapping mutations on phylogenies. Systematic Robison, R. A. 1965. Middle Cambrian eocrinoids from western Biology 51:729–739. North America. Journal of Paleontology 39: 355–364. Ogg, J. G., G. Ogg, and F. M. Gradstein. 2016. A concise geologic Ronquist, F. 1997. Dispersal-vicariance analysis: a new approach to time scale: 2016. Elsevier, Amsterdam. the quantification of historical biogeography. Systematic Biology O’Meara, B. C., C. Ané, M. J. Sanderson, and P. C. Wainwright. 46:195–203. 2006. Testing for different rates of continuous trait evolution Rozhnov, S. V. 2013. A new genus of Parablastoidea (Echinoder- using likelihood. Evolution 60:922–933. mata) from the Middle Ordovician of Ladoga glint on the Paul, C. R. C. 1968. Morphology and function of dichoporite Volkhov River (Ladoga region). Paleontological Journal 47: pore-structures in cystoids. Palaeontology 11:697–730. 154–161. Paul, C. R. C. 1988. The phylogeny of the cystoids. Pp. 199–213 in Saltzman, M. R., and S. A. Young. 2005. Long-lived glaciations in C. R. C. Paul and A. B. Smith, eds. Echinoderm phylogeny and the Late Ordovician? Isotopic and sequence-stratigraphic evi- evolutionary biology. Clarendon Press, Oxford. dence from western Laurentia. Geology 33:109–112.

Saltzman, M. R., C. T. Edwards, J. M. Adrain, and S. R. Westrop. Sumrall, C. D., and S. Zamora. 2018. New Upper Ordovician 2015. Persistent oceanic anoxia and elevated extinction rates separ- edrioasteroids from Morocco. Geological Society of London Spe- ate the Cambrian and Ordovician radiations. Geology 43:807–810. cial Publication 485:SP485.6. Samygin, S. G. 2019. Formation of the back-arc slope of the island Sumrall, C. D., S. Heredia, C. M. Rodríguez, and A. I. Mestre. 2013. arc of Chingiz Caledonide Range in the Eastern Kazakhstan. Geo- The first report of South American edrioasteroids and the paleo- tectonics 53:231–238. ecology and ontogeny of rhenopyrgid echinoderms. Acta Saupe, E. E., H. Qiao, Y. Donnadieu, A. Farnsworth, A. T. Palaeontologica Polonica 58:763–777. Kennedy-Asser, J.-B. Ladant, D. J. Lunt, A. Pohl, P. Valdes, and Sumrall, C. D., B. Deline, J. Colmenar, S. L. Sheffield, S. Zamora. S. Finnegan. 2020. Extinction intensity during Ordovician and 2015. New data on late Ordovician (Katian) echinoderms from Cenozoic glaciations explained by cooling and palaeogeography. Sardinia, Italy. Pp. 159–162 in S. Zamora and I. Rábano, eds. Pro- Nature Geoscience 13:65–70. gress in echinoderm palaeobiology. Cuademos del Museo Geo- Scotese, C. R., and W. S. McKerrow. 1991. Ordovician plate tectonic minero 19. Instituto Geológico y Minero de España, Madrid. reconstructions. Geological Survey of Canada Paper 90:225–234. Sutcliffe, O. E., J. A. Dowdeswell, R. J. Whittington, J. N. Theron, Scotese, C. R., A. J. Boucot, and W. S. McKerrow. 1999. Gondwanan and J. Craig. 2000. Calibrating the Late Ordovician glaciation palaeogeography and paleoclimatology. Journal of African Earth and mass extinction by the eccentricity cycles of Earth’s orbit. Sciences 28:99–114. Geology 28:967–970. Shanmugam, G., and G. G. Lash. 1982. Analogous tectonic evolu- Tarver, J. E., S. J. Braddy, and M. J. Benton. 2007. The effects of sam- tion of the Ordovician foredeeps, southern and central Appala- pling bias on Palaeozoic faunas and implications for macroevolu- chians. Geology 10:562–566. tionary studies. Palaeontology 50:177–184. Sheehan, P. M. 2001. The late Ordovician mass extinction. Annual Thompson, T. L., and T. L. Satterfield. 1975. Stratigraphy and cono- Review of Earth and Planetary Sciences 29:331–364. dont biostratigraphy of strata contiguous to the Ordovician–Silur- Sheffield, S. L., and C. D. Sumrall. 2017. Generic revision of the ian boundary in eastern Missouri. Missouri Geological Survey Holocystitidae of North America (Diploporita, Echinodermata) Report of Investigations 57:61–108. based on universal elemental homology. Journal of Paleontology Torsvik, T. H., and L. R. M. Cocks. 2013. New global palaeogeo- 91:755–766. graphical reconstructions for the Early Palaeozoic and their gen- Sheffield, S. L., and C. D., Sumrall. 2019a. The phylogeny of the eration. Geological Society of London Memoir 38:5–24. Diploporita: a polyphyletic assemblage of blastozoan echino- Trotter, J. A., I. S. Williams, C. R. Barnes, C. Leécuyer, and R. S. derms. Journal of Paleontology 93:740–752. Nicoll. 2008. Did cooling oceans trigger Ordovician biodiversifica- Sheffield, S. L., and C. D. Sumrall. 2019b. A re-interpretation of the tion? Evidence from conodont thermometry. Science 25:550–554. ambulacral system of Eumorphocystis (Blastozoa: Echinodermata) Trubovitz, S., and A. L. Stigall. 2016. Synchronous diversification of and its bearing on the evolution of early crinoids. Palaeontology Laurentian and Baltic rhynchonelliform brachiopods: implica- 62:163–173. tions for regional versus global triggers of the Great Ordovician Sheffield, S. L., W. I. Ausich, and C. D. Sumrall. 2017. Late Ordovi- Biodiversification Event. Geology 44:743–746. cian (Hirnantian) diploporitan fauna of Anticosti Island, Quebec, Turner, B. R., H. A. Armstrong, C. R. Wilson, and I. M. Makhlouf. Canada: implications for evolutionary and biogeographic pat- 2012. High frequency eustatic sea-level changes during the Mid- terns. Canadian Journal of Earth Sciences 55:1–7. dle to early Late Ordovician of southern Jordan: indirect evidence Sinnesael, M., A. Desrochers, C. M. Ø. Rasmussen, P. Claeys, and for a Darriwilian Ice Age in Gondwana. Sedimentary Geology T. R. A. Vandenbroucke. 2019. Identifying precession and obli- 251:34–48. quity cycles in the Ordovician? Geological Society of America, Vandenbroucke, T. R. A., H. A. Armstrong, M. Williams, J. A. Abstracts with Programs 51. doi: 10.1130/abs/2019AM-341409. Zalasiewicz, and K. Sabbe. 2009. Ground-truthing Late Ordovi- Soper, N. J., R. A. Strachan, R. E. Holdsworth, R. A. Gayer, and R. cian climate models using the paleobiogeography of graptolites. O. Greiling. 1992. Sinistral transpression and the Silurian closure Paleoceanography 24:1–19. of Iapetus. Journal of the Geological Society 149:871–880. van de Pluijm, B. A., R., R. van der Too, and T. H. Torsvik. 1995. Sprinkle, J. 1973. Morphology and evolution of blastozoan echino- Convergence and subduction at the Ordovician margin of derms. Harvard University Museum of Comparative Zoology Laurentia. Pp. 127–136 in J. P. Hibbard, C. R. van Staal, and P. A. Special Publication. Museum of Comparative Zoology, Cam- Cawood, eds. Current perspectives in the Appalachian–Caledonian bridge, Mass. orogen. Geological Association of Canada Special Paper 41. Stigall, A. L. 2018. How is biodiversity produced? Examining spe- St. John’s, NL, Canada. ciation processes during the GOBE. Lethaia 51:165–172. Webby, B. D., F. Paris, M. L. Droser, and I. G. Percival. 2004. The Stigall, A. L., J. E. Bauer, A. R. Lam, D. F. Wright. 2017. Biotic Great Ordovician Biodiversification Event. Columbia University immigration events, speciation, and the accumulation of bio- Press, New York. diversity in the fossil record. Global and Planetary Change Wilde, P. 1991. Oceanography in the Ordovician. Pp. 225–344 in C. R. 148:242–257. Barnes and S. H. Williams, eds. Advances in Ordovician geology. Stigall, A. L., C. T. Edwards, R. L. Freeman, and C. M. Ø. Rasmussen. Geological Survey of Canada Paper 90. St. John’s, NL, Canada. 2019. Coordinated biotic and abiotic change during the Great Wright, D. F., and A. L. Stigall. 2013. Geologic drivers of Late Ordo- Ordovician Biodiversification Event: Darriwilian assembly of vician faunal change in Laurentia: investigating links between early Paleozoic building blocks. Palaeoceanography, Palaeo- tectonics, speciation, and biotic invasions. PLoS ONE 8:e68353. climatology, Palaeoecology 530:249–270. Wright, D. F., and U. Toom. 2017. New crinoids from the Baltic Sumrall, C. D. 1997. The role of fossils in the phylogenetic recon- region (Estonia): fossil tip-dating phylogenetics constrains the struction of Echinodermata. Paleontological Society Papers origin and Ordovician–Silurian diversification of the Flexibilia 3:267–288. (Echinodermata). Palaeontology 60:893–910. Sumrall, C. D. 2010. A model for elemental homology for the peri- Young, A. L., C. E. Brett, and P. I. McLaughlin. 2015. Upper Ordo- stome and ambulacra in blastozoan echinoderms. Pp. 269–276 in vician (Sandbian–Katian) sub-surface stratigraphy of the Cincin- L. G. Harris, S. A. Böttger, C. W. Walker, and M. P. Lesser, eds. nati Region (Ohio, USA): transition into the Sebree Trough. Echinoderms: Durham. CRC Press, London. Stratigraphy:12:297–305. Sumrall, C. D., and S. Zamora. 2011. Ordovician edrioasteroids Young, S. A., B. C. Gill, C. T. Edwards, M. R. Saltzman, and S. A. from Morocco: faunal exchanges across the Rheic Ocean. Journal Leslie. 2016. Middle–Late Ordovician (Darriwilian–Sandbian) of Systematic Palaeontology 9:425–454. decoupling of global sulfur and carbon cycles: isotopic evidence

from eastern and southern Laurentia. Palaeogeography, Palaeo- R. Parsley, S. V. Rozhnov, J. Sprinkle, C. D. Sumrall, climatology, Palaeoecology 458:118–132. D. Vizcaino, and A. B. Smith. 2013. Cambrian echinoderm Zagorevski, A., and C. R. Van Staal. 2011. The record of Ordovician diversity and palaeobiogeography. Geological Society of Lon- arc–arc and arc–continent collisions in the Canadian Appala- don Memoir 38:157–171. chians during the closure of Iapetus. Pp. 341–372 in D. Brown Zamora, S., C. D. Sumrall, X.-J. Zhu, B. Lefebvre. 2016. A new and P. D. Ryan, eds. Arc–continent collision. Frontiers in earth stemmed echinoderm from the Furongian of China and the origin sciences. Springer, Berlin. of Glyptocystitida (Blastozoa, Echinodermata). Geological Maga- Zamora, S., and A. B. Smith. 2008. A new Middle Cambrian stem- zine 154:465–475. group echinoderm from Spain: paleobiological implications of a Zhang, Q., S. Buckman, V. C. Bennett, and A. Nutman. 2019. highly asymmetric cinctan. Acta Palaeontologica Polonica 53: Inception and early evolution of the Ordovician Macquarie 207–221. Arc of Eastern Gondwana margin: zircon U-Pb-Hf evidence Zamora, S., B. Lefebvre, B, J. J. Àlvaro, S. Clausen, O. Elicki, from the Molong Volcanic Belt, Lachlan Orogen. Lithos 326: O. Fatka, P. Jell, A. Kouchinsky, J.-P. Lin, E. Nardin, 513–528.