DOCSLIB.ORG

Phyllolepis Rossimontina Sp. Nov. (Placodermi) from the Uppermost Devonian at Red Hill, North-Central Pennsylvania

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Phyllolepis Rossimontina Sp. Nov. (Placodermi) from the Uppermost Devonian at Red Hill, North-Central Pennsylvania Revista Brasileira de Paleontologia 8(2):117-126, Maio/Agosto 2005 © 2005 by the Sociedade Brasileira de Paleontologia PHYLLOLEPIS ROSSIMONTINA SP. NOV. (PLACODERMI) FROM THE UPPERMOST DEVONIAN AT RED HILL, NORTH-CENTRAL PENNSYLVANIA JENNIFER A. LANE Division of Paleontology (Vertebrate), American Museum of Natural History, Central Park West at 79th Street, New York 10024, USA. [email protected] ROGER J. CUFFEY Department of Geosciences, 412 Deike Bldg., Pennsylvania State University, University Park, Pennsylvania 16802,USA. [email protected] ABSTRACT - Phyllolepid placoderms were heretofore known almost entirely from Greenland, western Europe, Australia, and Antarctica. Now, a suite of 31 specimens are here recognized from the United States. The locality yielding these fossils is Red Hill, a roadcut exposing late Famennian redbeds (Duncannon Member, Catskill Formation, Uppermost Devonian), east of Renovo, Clinton County, north-central Pennsylvania. One partially articulated individual, plus several isolated plates, represent Phyllolepis rossimontina sp. nov., described herein. Additional dissociated plates may represent variants of this new species, or alternatively may belong to the previously recognized species Phyllolepis concentrica, P. nielseni, P. undulata, or P. woodwardi. A single plate described as P. delicatula over a century ago from slightly older strata farther east in Pennsylvania is morphologically distinct from any of the Red Hill specimens. Key words: Phyllolepids, placoderms, fishes, Devonian, Famennian, Pennsylvania. RESUMO - Até o presente, placodermos filolepídeos eram conhecidosAS somente na Groenlândia, oeste da Europa, Austrália e Antártica. Recentemente, um conjunto de 31 espécimens foi reconhecido na localidade de Red Hill nos Estados Unidos. Nesta localidade, os fósseis provêm de um corte de estrada, expondo redbeds” do Fameniano Superior (Membro Duncannon, Formação Catskill, parte superior do Devoniano Superior), leste de Renovo, Distrito de Clinton, central-norte de Pensilvânia. Um indivíduo parcialmente articulado, além de várias placas isoladas, representam Phyllolepis rossimontina sp.nov., aqui descrita. Outras placas adicionais, disarticuladas, podem representar variações desta nova espécie ou, alternativamente, podem pertencer a outras espécies já conhecidas, tais como: Phyllolepis concentrica, P. nielseni, P. undulata, ou P. woodwardi. Há mais de um século, uma única placa foi descrita como P. delicatula, proveniente de camadas ligeiramente mais antigas, ao leste da Pensilvânia. Phyllolepis delicatula é morfológicamente distinta dos espécimens de Red Hill. Palavras-chave: Filolepídeos, placodermos,PRO peixes, Devoniano,V Famenniano, Pensilvania. INTRODUCTION described (Thomson, 1968; Daeschler et al., 1994; Daeschler, 2000a, 2000b). The objectives of this paper are to describe a new species of phyllolepid placoderm, and to report on the suite of GEOLOGIC SETTING phyllolepid specimens, from the Late Devonian Red Hill locality in north-central Pennsylvania.These phyllolepids Red Hill is a long, high roadcut located along Pennsylvania represent the first sizeable suite of specimens found in North Highway 120, 5.8-6.8 km east of the junction of PA Highways America (exclusive of Greenland), and hence are of special 120 and 144 (southbound) on the northeastern side of Renovo scientific significance (Lane et al., 2001). Phyllolepids have (Figure 1). previously been described from Greenland, Scotland, Belgium, Rock strata exposed at this locality belong to the Lithuania, Turkey, Russia, Australia, and Antarctica (Denison, Duncannon Member of the deltaic Catskill Formation, of Late 1978; Long, 1984; Ritchie, 1984). Famennian (Latest Devonian) age (Woodrow et al., 1995; Basal tetrapod (early amphibian) fossils, as well as other Inners, 1987; Harper, 1999; Daeschler, 2000b; Lane, 2001). placoderm, chondrichthyan, actinopterygian, and The phyllolepids come from a thin (2 m) zone low in the cliff crossopterygian fishes from Red Hill have already been in the eastern part of the roadcut (Woodrow et al., 1995). 117 118 REVISTA BRASILEIRA DE PALEONTOLOGIA, 8(2), 2005 The classification of phyllolepids used here is based on Denison (1978). An alternative classification has been suggested by Long (1984:303-304), in which phyllolepids are placed in the Order Euarthrodira Gross, 1932, under the Suborder Actinolepidoidei Miles & Young, 1977, and Infraorder Phyllolepidi Long, 1984. Abbreviations used in text and figures. Al, anterior lateral; Figure 1. Location of Red Hill roadcut (arrow); base from Avl, anterior ventrolateral; csl, central sensory line canal; Williamsport West 0.5°x1.0° topographic quadrangle (U.S. Geological Md, median dorsal; Nu, nuchal; Pn, postnasal; ppl, posterior Survey, 1984); inset shows location within Pennsylvania; upper pit line canal;Pnu, paranuchal; Pvl, posterior ventro-lateral; scale in kilometers, lower in miles; north towards top of page. Sp, spinal; soc, supraorbital canal. MATERIALS AND METHODS SYSTEMATIC PALEONTOLOGY A total of 31 phyllolepid specimens from Red Hill were Class PLACODERMI M’Coy, 1848 examined for the purposes of this study (Lane, 2001). These Order PHYLLOLEPIDA Stensiö, 1934 specimens are all curated at the Academy of Natural Sciences Suborder PHYLLOLEPINA Stensiö, 1934 of Philadelphia (ANSP). In addition to these, the holotype of Family PHYLLOLEPIDAE Woodward, 1891 Phyllolepis delicatula Newberry, 1889, housed in the Genus PHYLLOLEPIS Agassiz, 1844 American Museum of Natural History (AMNH 6807) was examined and compared to the Red Hill material. Most of the Type Species. Phyllolepis concentrica Agassiz, 1844. literature comparisons focus on Stensiö’s (1934, 1936, 1939) Diagnosis. Stensiö (1934:34). Full generic description: Stensiö descriptions. (1934:13-34; 1936:8-28). The most nearly complete, partly articulated, Red Hill specimen (ANSP 20822; Figures 2-3) differs enough from Phyllolepis rossimontina sp. nov . previously published phyllolepid species that it warrants (Figures 2-4) description as a new species of the order. Following the new species description are comments about some isolated Red Holotype. ANSP 20822, a partially articulated individual Hill plates which more closely resemble other species preserved as part and counterpart (Figure 2-3); including previously described in the literature. Possible alternative nuchal, postnasal, right and left paranuchals, left spinal interpretations are discussed where appropriate. (Figure 4C), right and left anterior ventro-laterals, right and When confronted with a number of isolated bones, left posterior ventro-laterals, and possible additional small especially if representing several different plate types, it is head plates (perhaps instead broken chips of the adjacent difficult to determine which ones may represent the same nuchal). species. A little variability almost always exists among such Referred materials. Isolated plates essentially identical to specimens, thus leading to debates about considering all as those preserved in the holotype: Nuchals (Nu): ANSP 20810, variants of only one species, versus viewing most as ANSP 20821 (Figure 4A-B), ANSP 21186; Anterior ventro- belonging to many different species. Not enough is yet known laterals (Avl): ANSP 20818A and B, ANSP 20826A and B PROVAS(Figure 4D-E), ANSP 20827A and B, ANSP 21405; also about phyllolepid morphology and variation to be able to diagnostically characterize every loose plate with certainty. possibly ANSP 21185; Anterior ventro-lateral (Avl) However, some published species are known from relatively overlapped upon a posterior ventro-lateral (Pvl): ANSP 21293. complete specimens, showing the shapes, sizes, and details Etymology. From Italian, after the locality name (Red Hill): of particular bone plates; some of the isolated plates can be rossi meaning red, montina meaning small mountain or hill. matched with individual bones in those complete specimens, Diagnosis. Phyllolepis with the following unique combination thereby suggesting tentative or possible identification with of morphologic character states: Nuchal (Nu) plate broader those species. than long, the length 80% of the breadth (on the holotype; Other previously described species are known from such varying 70-85% on additional isolated Nu plates); ornamented fragmentary remains that relating isolated Red Hill plates to with numerous pits and tubercles on its anterior portion; them is nearly impossible. Finally, studies of placoderm corners “flared” or projecting where the anterolateral and intraspecific variability (especially in the abundant posterolateral corners of the nuchal are joined; posterior bothriolepids; Werdelin & Long, 1986) may stimulate margin of nuchal straight/non-curved, and posterolateral additional insight into such questions, although the Red Hill margins strongly curved. Anterior ventro-lateral plates with phyllolepid suite presently available is too limited for a an exaggerated forward-extending point on the anteromedial comprehensive allometric study like theirs. corner as the most distinctive character; anterior margin LANE & CUFFEY – NEW PHYLLOLEPID FROM DEVONIAN OF NORTH AMERICA 119 Figure 2. Phyllolepis rossimontina sp. nov., photographs of ANSP 20822 (holotype); scale bars =10 mm. A, entire specimen (“part”), showing Nu, right and left Pnu, possible other smaller head plates, right and left Avl, left Sp, and right Pvl; B, entire counterpart, showing Nu, right and left Pnu, Pn, right and left Avl, left Sp, and right and left Pvl. sloping steeply
Load more

Recommended publications
  • FISHING for DUNKLEOSTEUS You’Re Definitely Gonna Need a Bigger Boat by Mark Peter
    OOhhiioo GGeeoollooggyy EEXXTTRRAA July 31, 2019 FISHING FOR DUNKLEOSTEUS You’re definitely gonna need a bigger boat by Mark Peter At an estimated maximum length of 6 to 8.8 meters (20–29 sediments that eroded from the Acadian Mountains, combined feet), Dunkleosteus terrelli (Fig. 1) would have been a match for with abundant organic matter from newly evolved land plants even the Hollywood-sized great white shark from the and marine plankton, settled in the basin as dark organic movie Jaws. Surfers, scuba divers, and swimmers can relax, muds. Over millions of years, accumulation of additional however, because Dunkleosteus has been extinct for nearly 360 overlying sediments compacted the muds into black shale rock. million years. Dunkleosteus was a placoderm, a type of armored The rocks that formed from the Late Devonian seafloor fish, that lived during the Late Devonian Period from about sediments (along with fossils of Dunkleosteus) arrived at their 375–359 million years ago. Fossil remains of the large present location of 41 degrees north latitude after several species Dunkleosteus terrelli are present in the Cleveland hundred million years of slow plate tectonic movement as the Member of the Ohio Shale, which contains rocks that are North American Plate moved northward. approximately 360–359 million years old. Figure 1. A reconstruction of a fully-grown Dunkleosteus terrelli, assuming a length of 29 feet, with angler for scale. Modified from illustration by Hugo Salais of Metazoa Studio. Dunkleosteus cruised Late Devonian seas and oceans as an Figure 2. Paleogeographic reconstruction of eastern North America during apex predator, much like the great white shark of today.
    [Show full text]
  • Cambridge University Press 978-1-107-17944-8 — Evolution And
    Cambridge University Press 978-1-107-17944-8 — Evolution and Development of Fishes Edited by Zerina Johanson , Charlie Underwood , Martha Richter Index More Information Index abaxial muscle,33 Alizarin red, 110 arandaspids, 5, 61–62 abdominal muscles, 212 Alizarin red S whole mount staining, 127 Arandaspis, 5, 61, 69, 147 ability to repair fractures, 129 Allenypterus, 253 arcocentra, 192 Acanthodes, 14, 79, 83, 89–90, 104, 105–107, allometric growth, 129 Arctic char, 130 123, 152, 152, 156, 213, 221, 226 alveolar bone, 134 arcualia, 4, 49, 115, 146, 191, 206 Acanthodians, 3, 7, 13–15, 18, 23, 29, 63–65, Alx, 36, 47 areolar calcification, 114 68–69, 75, 79, 82, 84, 87–89, 91, 99, 102, Amdeh Formation, 61 areolar cartilage, 192 104–106, 114, 123, 148–149, 152–153, ameloblasts, 134 areolar mineralisation, 113 156, 160, 189, 192, 195, 198–199, 207, Amia, 154, 185, 190, 193, 258 Areyongalepis,7,64–65 213, 217–218, 220 ammocoete, 30, 40, 51, 56–57, 176, 206, 208, Argentina, 60–61, 67 Acanthodiformes, 14, 68 218 armoured agnathans, 150 Acanthodii, 152 amphiaspids, 5, 27 Arthrodira, 12, 24, 26, 28, 74, 82–84, 86, 194, Acanthomorpha, 20 amphibians, 1, 20, 150, 172, 180–182, 245, 248, 209, 222 Acanthostega, 22, 155–156, 255–258, 260 255–256 arthrodires, 7, 11–13, 22, 28, 71–72, 74–75, Acanthothoraci, 24, 74, 83 amphioxus, 49, 54–55, 124, 145, 155, 157, 159, 80–84, 152, 192, 207, 209, 212–213, 215, Acanthothoracida, 11 206, 224, 243–244, 249–250 219–220 acanthothoracids, 7, 12, 74, 81–82, 211, 215, Amphioxus, 120 Ascl,36 219 Amphystylic, 148 Asiaceratodus,21
    [Show full text]
  • 'Placoderm' (Arthrodira)
    Jobbins et al. Swiss J Palaeontol (2021) 140:2 https://doi.org/10.1186/s13358-020-00212-w Swiss Journal of Palaeontology RESEARCH ARTICLE Open Access A large Middle Devonian eubrachythoracid ‘placoderm’ (Arthrodira) jaw from northern Gondwana Melina Jobbins1* , Martin Rücklin2, Thodoris Argyriou3 and Christian Klug1 Abstract For the understanding of the evolution of jawed vertebrates and jaws and teeth, ‘placoderms’ are crucial as they exhibit an impressive morphological disparity associated with the early stages of this process. The Devonian of Morocco is famous for its rich occurrences of arthrodire ‘placoderms’. While Late Devonian strata are rich in arthrodire remains, they are less common in older strata. Here, we describe a large tooth-bearing jaw element of Leptodontich- thys ziregensis gen. et sp. nov., an eubrachythoracid arthrodire from the Middle Devonian of Morocco. This species is based on a large posterior superognathal with a strong dentition. The jawbone displays features considered syna- pomorphies of Late Devonian eubrachythoracid arthrodires, with one posterior and one lateral row of conical teeth oriented postero-lingually. μCT-images reveal internal structures including pulp cavities and dentinous tissues. The posterior orientation of the teeth and the traces of a putative occlusal contact on the lingual side of the bone imply that these teeth were hardly used for feeding. Similar to Compagopiscis and Plourdosteus, functional teeth were pos- sibly present during an earlier developmental stage and have been worn entirely. The morphological features of the jaw element suggest a close relationship with plourdosteids. Its size implies that the animal was rather large. Keywords: Arthrodira, Dentition, Food web, Givetian, Maïder basin, Palaeoecology Introduction important to reconstruct character evolution in early ‘Placoderms’ are considered as a paraphyletic grade vertebrates.
    [Show full text]
  • Arthrodira, Homostiidae) from the Emsian of Aragón, Spain, and Its Distribution
    FISH FROM THE EMSIAN OF ARAGÓN 139 Tityosteus, A MARINE FISH (ARTHRODIRA, HOMOSTIIDAE) FROM THE EMSIAN OF ARAGÓN, SPAIN, AND ITS DISTRIBUTION Elga MARK-KURIK1 and Peter CARLS2 1 Institute of Geology. Tallinn University of Technology, Estonia Avenue 7, 10143 Tallinn, Estonia. E-mail: [email protected] 2 Institut für Umweltgeologie, Technische Universität, Braunschweig, Pockels- Str. 3, D 38106, Germany. Mark-Kurik, E. and Carls, P. 2004. Tityosteus, a marine fish (Arthrodira, Homostiidae) from the Emsian of Aragón, Spain, and its distribution. [Tityosteus, un pez marino (Arthrodira, Homostiidae) del Emsiense de Aragón, España, y su distribución.] Revista Española de Paleontología, 19 (2), 139-144. ISSN 0213-6937. ABSTRACT A right marginal plate (over 11 cm long) of Tityosteus cf. rieversae Gross, 1960, emend., has been found in the late part of the Early Emsian (late Zlichovian) in the Mariposas Fm. of the Eastern Iberian Cordillera in south- ern Aragón. The palaeoecological conditions correspond to a hemipelagic ensialic basin, with predominant ele- ments of Hercynic biofacies but still with photic bottom. The Emsian genus Tityosteus is now known from the Hunsrück Schiefer of Germany and the closely connected Ibero-Armorican Trough and also from the more dis- tant Minusinsk Basin of southern Siberia. Palaeo-oceans between western Europe and southern Siberia were no zoogeographical barriers for these large, possibly microphagous fishes in open sea. The name of the type spe- cies of Tityosteus is emended. Keywords: Placodermi, marginal plate, palaeoecology, palaeozoogeography, late Zlichovian. RESUMEN Se describe una placa marginal derecha (más de 11 cm de longitud) de Tityosteus cf. rieversae Gross, 1960, emend., de la parte tardía del Emsiense Inferior (Zlichoviense tardío) de la Fm.
    [Show full text]
  • Contributions in BIOLOGY and GEOLOGY
    MILWAUKEE PUBLIC MUSEUM Contributions In BIOLOGY and GEOLOGY Number 51 November 29, 1982 A Compendium of Fossil Marine Families J. John Sepkoski, Jr. MILWAUKEE PUBLIC MUSEUM Contributions in BIOLOGY and GEOLOGY Number 51 November 29, 1982 A COMPENDIUM OF FOSSIL MARINE FAMILIES J. JOHN SEPKOSKI, JR. Department of the Geophysical Sciences University of Chicago REVIEWERS FOR THIS PUBLICATION: Robert Gernant, University of Wisconsin-Milwaukee David M. Raup, Field Museum of Natural History Frederick R. Schram, San Diego Natural History Museum Peter M. Sheehan, Milwaukee Public Museum ISBN 0-893260-081-9 Milwaukee Public Museum Press Published by the Order of the Board of Trustees CONTENTS Abstract ---- ---------- -- - ----------------------- 2 Introduction -- --- -- ------ - - - ------- - ----------- - - - 2 Compendium ----------------------------- -- ------ 6 Protozoa ----- - ------- - - - -- -- - -------- - ------ - 6 Porifera------------- --- ---------------------- 9 Archaeocyatha -- - ------ - ------ - - -- ---------- - - - - 14 Coelenterata -- - -- --- -- - - -- - - - - -- - -- - -- - - -- -- - -- 17 Platyhelminthes - - -- - - - -- - - -- - -- - -- - -- -- --- - - - - - - 24 Rhynchocoela - ---- - - - - ---- --- ---- - - ----------- - 24 Priapulida ------ ---- - - - - -- - - -- - ------ - -- ------ 24 Nematoda - -- - --- --- -- - -- --- - -- --- ---- -- - - -- -- 24 Mollusca ------------- --- --------------- ------ 24 Sipunculida ---------- --- ------------ ---- -- --- - 46 Echiurida ------ - --- - - - - - --- --- - -- --- - -- - - ---
    [Show full text]
  • Ornamentation of Dermal Bones of Placodermi from the Lower Devonian of Morocco As a Measure of Biodiversity
    Mateusz Antczak, Błażej Berkowski Geologos 23, 2 (2017): 65–73 doi: 10.1515/logos-2017-0009 Ornamentation of dermal bones of Placodermi from the Lower Devonian of Morocco as a measure of biodiversity Mateusz Antczak1*, Błażej Berkowski1 1Adam Mickiewicz University, Faculty of Geographical and Geological Sciences, Institute of Geology, Department of Palaeontology and Stratigraphy, Krygowskiego 12, 61-680 Poznań, Poland * corresponding author, e-mail: [email protected] Abstract Dermal bones are formed early during growth and thus constitute an important tool in studies of ontogenetic and evo- lutionary changes amongst early vertebrates. Ornamentation of dermal bones of terrestrial vertebrates is often used as a taxonomic tool, for instance in Aetosauria, extant lungfishes (Dipnoi) and ray-finned fishes (Actinopterygii), for which it have been proved to be of use in differentiating specimens to species level. However, it has not been utilised to the same extent in placoderms. Several features of the ornamentation of Early Devonian placoderms from Hamar Laghdad (Morocco) were examined using both optical and scanning electron microscopy to determine whether it is possible to distinguish armoured Palaeozoic fishes. Four distinct morphotypes, based on ornamentation of dermal bones, are dif- ferentiated. These distinct types of ornamentation may be the result of either different location of dermal plates on the body or of ontogenetic (intraspecific) and/or interspecific variation. Keywords: Arthrodira, interspecific variation, ontogeny, fishes, North Africa 1. Introduction both between species and ontogenetic stages (Tri- najstic, 1999); acanthodians are almost exclusively Dermal bones, or membranous bones, form known by scale taxa (Brazeau & Friedman, 2015), as without a chondral stage; in extant fish taxa these are many sharks (e.g., Martin, 2009).
    [Show full text]
  • Copyrighted Material
    06_250317 part1-3.qxd 12/13/05 7:32 PM Page 15 Phylum Chordata Chordates are placed in the superphylum Deuterostomia. The possible rela- tionships of the chordates and deuterostomes to other metazoans are dis- cussed in Halanych (2004). He restricts the taxon of deuterostomes to the chordates and their proposed immediate sister group, a taxon comprising the hemichordates, echinoderms, and the wormlike Xenoturbella. The phylum Chordata has been used by most recent workers to encompass members of the subphyla Urochordata (tunicates or sea-squirts), Cephalochordata (lancelets), and Craniata (fishes, amphibians, reptiles, birds, and mammals). The Cephalochordata and Craniata form a mono- phyletic group (e.g., Cameron et al., 2000; Halanych, 2004). Much disagree- ment exists concerning the interrelationships and classification of the Chordata, and the inclusion of the urochordates as sister to the cephalochor- dates and craniates is not as broadly held as the sister-group relationship of cephalochordates and craniates (Halanych, 2004). Many excitingCOPYRIGHTED fossil finds in recent years MATERIAL reveal what the first fishes may have looked like, and these finds push the fossil record of fishes back into the early Cambrian, far further back than previously known. There is still much difference of opinion on the phylogenetic position of these new Cambrian species, and many new discoveries and changes in early fish systematics may be expected over the next decade. As noted by Halanych (2004), D.-G. (D.) Shu and collaborators have discovered fossil ascidians (e.g., Cheungkongella), cephalochordate-like yunnanozoans (Haikouella and Yunnanozoon), and jaw- less craniates (Myllokunmingia, and its junior synonym Haikouichthys) over the 15 06_250317 part1-3.qxd 12/13/05 7:32 PM Page 16 16 Fishes of the World last few years that push the origins of these three major taxa at least into the Lower Cambrian (approximately 530–540 million years ago).
    [Show full text]
  • Redescription of Yinostius Major (Arthrodira: Heterostiidae) from the Lower Devonian of China, and the Interrelationships of Brachythoraci
    bs_bs_banner Zoological Journal of the Linnean Society, 2015. With 10 figures Redescription of Yinostius major (Arthrodira: Heterostiidae) from the Lower Devonian of China, and the interrelationships of Brachythoraci YOU-AN ZHU1,2, MIN ZHU1* and JUN-QING WANG1 1Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China 2University of Chinese Academy of Sciences, Beijing 100049, China Received 29 December 2014; revised 21 August 2015; accepted for publication 23 August 2015 Yinosteus major is a heterostiid arthrodire (Placodermi) from the Lower Devonian Jiucheng Formation of Yunnan Province, south-western China. A detailed redescription of this taxon reveals the morphology of neurocranium and visceral side of skull roof. Yinosteus major shows typical heterostiid characters such as anterodorsally positioned small orbits and rod-like anterior lateral plates. Its neurocranium resembles those of advanced eubrachythoracids rather than basal brachythoracids, and provides new morphological aspects in heterostiids. Phylogenetic analysis based on parsimony was conducted using a revised and expanded data matrix. The analysis yields a novel sce- nario on the brachythoracid interrelationships, which assigns Heterostiidae (including Heterostius ingens and Yinosteus major) as the sister group of Dunkleosteus amblyodoratus. The resulting phylogenetic scenario suggests that eubrachythoracids underwent a rapid diversification during the Emsian, representing the placoderm response to the Devonian Nekton Revolution. The instability of the relationships between major eubrachythoracid clades might have a connection to their longer ghost lineages than previous scenarios have implied. © 2015 The Linnean Society of London, Zoological Journal of the Linnean Society, 2015 doi: 10.1111/zoj.12356 ADDITIONAL KEYWORDS: Brachythoraci – Heterostiidae – morphology – phylogeny – Placodermi.
    [Show full text]
  • The Earliest Phyllolepid (Placodermi, Arthrodira) from the Late Lochkovian (Early Devonian) of Yunnan (South China)
    Geol. Mag. 145 (2), 2008, pp. 257–278. c 2007 Cambridge University Press 257 doi:10.1017/S0016756807004207 First published online 30 November 2007 Printed in the United Kingdom The earliest phyllolepid (Placodermi, Arthrodira) from the Late Lochkovian (Early Devonian) of Yunnan (South China) V. DUPRET∗ &M.ZHU Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, P.O. Box 643, Xizhimenwai Dajie 142, Beijing 100044, People’s Republic of China (Received 1 November 2006; accepted 26 June 2007) Abstract – Gavinaspis convergens, a new genus and species of the Phyllolepida (Placodermi: Arthrodira), is described on the basis of skull remains from the Late Lochkovian (Xitun Formation, Early Devonian) of Qujing (Yunnan, South China). This new form displays a mosaic of characters of basal actinolepidoid arthrodires and more derived phyllolepids. A new hypothesis is proposed concerning the origin of the unpaired centronuchal plate of the Phyllolepida by a fusion of the paired central plates into one single dermal element and the loss of the nuchal plate. A phylogenetic analysis suggests the position of Gavinaspis gen. nov. as the sister group of the Phyllolepididae, in a distinct new family (Gavinaspididae fam. nov.). This new form suggests a possible Chinese origin for the Phyllolepida or that the common ancestor to Phyllolepida lived in an area including both South China and Gondwana, and in any case corroborates the palaeogeographic proximity between Australia and South China during the Devonian Period. Keywords: Devonian, China, Placodermi, phyllolepids, biostratigraphy, palaeobiogeography. 1. Introduction 1934). Subsequently, they were considered as either sharing an immediate common ancestor with the The Phyllolepida are a peculiar group of the Arthrodira Arthrodira (Denison, 1978), belonging to the Actin- (Placodermi), widespread in the Givetian–Famennian olepidoidei (Long, 1984), or being of indetermined of Gondwana (Australia, Antarctica, Turkey, South position within the Arthrodira (Goujet & Young,1995).
    [Show full text]
  • A Large Late Devonian Arthrodire (Vertebrata, Placodermi) from Poland
    Estonian Journal of Earth Sciences, 2018, 67, 1, 33–42 https://doi.org/10.3176/earth.2018.02 A large Late Devonian arthrodire (Vertebrata, Placodermi) from Poland Piotr Szreka and Olga Wilkb a Polish Geological Institute–National Research Institute, 4 Rakowiecka Street, 00-975 Warszawa, Poland; [email protected] b Faculty of Geology, University of Warsaw, 93 Żwirki i Wigury Street, 02-089 Warszawa, Poland; [email protected] Received 1 August 2017, accepted 31 October 2017, available online 19 January 2018 Abstract. The arthrodire placoderm, Dunkleosteus sp., is reported from the Upper Devonian (Frasnian) of the Holy Cross Mountains, Poland. The material comprises partially preserved remains of two individuals found in the Kellwasser-like horizon of the Płucki locality. The remains are preserved as broken bone fragments redeposited from shallower environment into deep-shelf conditions. They are labelled as Dunkleosteus sp. and seem similar to Dunkleosteus marsaisi from the Famennian of Morocco. It is likely that the form from Poland represents a new species that requires further collecting and study of new specimens. The described specimens are the oldest occurrence of the genus Dunkleosteus in Europe, the most complete one from Poland and one of the biggest placoderms with a head about 60 cm long. Key words: Dunkleosteus, Upper Devonian, Frasnian, Holy Cross Mountains, Poland. INTRODUCTION D. marsaisi Lehman, 1954 from the early Famennian of Morocco (Lehman 1956). The genus Dunkleosteus (formerly Dinichthys in part) Although tens of placoderm fossil remains were includes about eight species (if including D. belgicus collected in Płucki during long-term excavation works (Leriche), 1931) which are found in Laurussia (USA, between 1996 and 2006 (see Szrek 2008, 2009; Szrek & Canada, Belgium, Poland) and Gondwana (Morocco).
    [Show full text]
  • Facies Differentiation and Late Devonian Placoderms Fossils in the Holy Cross Mountains
    Przegl¹d Geologiczny, vol. 54, nr 6, 2006 Zró¿nicowanie facjalne a skamienia³oœci póŸnodewoñskich plakodermów w Górach Œwiêtokrzyskich Piotr Szrek* Facies differentiation and Late Devonian placoderms fossils in the Holy Cross Mountains. Prz. Geol., 54: 521–524. S u m m a r y. Main Late Devonian placoderm taxa known from the Holy Cross Mountains are characterised. The distribution of the Late Devonian placoderm fossils is described. Variation in their occurrences depend on the sedimentation environment of the rocks which contain fossils of this group. Connections between the Holy Cross Mountains placoderms development and the synsedimentary tectonic processes active in this area during the Late Devonian is discussed, and the local faunas compared to classic assemblages of the same age from Latvia. Key words: Placodermi, synsedimentation tectonic, Late Devonian, facies, Holy Cross Mountains Placodermi (ryby pancerne) to gromada krêgowców Plakodermy œwiêtokrzyskie wodnych, która pojawi³a siê w sylurze, a wymar³a z koñcem dewonu. Ich maksymalny stopieñ zró¿nicowania Znalezione i opisane dotychczas póŸnodewoñskie pla- przypada na póŸny dewon — wtedy to plakodermy zdomi- kodermy z Gór Œwiêtokrzyskich mo¿na podzieliæ na dwie nowa³y niemal wszystkie morskie nisze ekologiczne, zasadnicze grupy. Kryterium zastosowanego podzia³u jest wytwarzaj¹c ró¿norodne typy specjalizacyjne, umo¿li- sposób zdobywania po¿ywienia oraz stopieñ przywi¹zania wiaj¹ce ¿ycie zarówno w otwartym basenie morskim, œro- do okreœlonych œrodowisk, a tak¿e stopieñ opancerzenia dowisku przyrafowym, jak te¿ w œrodowiskach cia³a. brakicznych. W Górach Œwiêtokrzyskich grupa ta jest Do pierwszej grupy mo¿na zaliczyæ wszystkie pla- bogato reprezentowana w materiale kopalnym i by³a oma- kodermy, bêd¹ce aktywnymi myœliwymi, u których pancerz wiana w licznych pracach od ponad stu lat (m.in.
    [Show full text]
  • Vertebrata: Placodermi) from the Famennian of Belgium
    View metadata, citationGEOLOGICA and similar papers BELGICA at core.ac.uk (2005) 8/1-2: 51-67 brought to you by CORE provided by Open Marine Archive A NEW GROENLANDASPIDID ARTHRODIRE (VERTEBRATA: PLACODERMI) FROM THE FAMENNIAN OF BELGIUM Philippe JANVIER1, 2 and Gaël CLÉMENT1 1. UMR 5143 du CNRS, Département «Histoire de la Terre», Muséum National d’Histoire Naturelle, 8 rue Buff on, 75005 Paris, France. [email protected] 2. 7 e Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom (9 fi gures, 1 table and 2 plates) ABSTRACT. A new species of the arthrodire genus Groenlandaspis is described from the upper part of the Evieux Formation (Upper Famennian), based on several specimens collected from quarries at Modave and Villers-le-Temple, Liège Province, Belgium. It is the fi rst occurrence of this widespread genus in continental Europe. O is new species is characterized by an almost smooth dermal armour, except for some scattered tubercles on its skull roof, median dorsal and spinal plates. Its median dorsal plate is triangular in shape and almost perfectly equilateral in lateral aspect and bears large, spiniform denticles on its posterior edge. All these Groenlandaspis remains occur in micaceous, dolomitic claystones or siltstones probably deposited in a subtidal environment. Outcrops of the same area have yielded other vertebrate remains, such as the placoderms Phyllolepis and Bothriolepis, acanthodians, various piscine sarcopterygians (Holoptychius, dipnoans, a rhizodontid, Megalichthys, Eusthenodon and a large tristichopterid), and a tetrapod that is probably close to Ichthyostega. O e biogeographical history of the genus Groenlandaspis is briefl y outlined, and the late Frasnian-Famennian interchange of vertebrate taxa between Gondwana and Euramerica is discussed.
    [Show full text]