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Tree of Life Media Contributed By Philippe Janvier

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ID Thumbnail Media Data
713
Scientific Name Astraspis desiderata
Location Colorado
Comments Astraspids are still poorly known but recent discoveries of partially complete specimens of Astraspis desiderata, from the Ordovician of Colorado, have considerably increased their knowledge. Their dorsal headshield is made up by large, polygonal bone units and the gill openings are situated more dorsally than in arandaspids.
Reference After Janvier 1996, modified from Elliott, D. K. (1987). A reassessment of Astraspis desiderata, the oldest North American vertebrate. Science, 237:190-192.
Specimen Condition Fossil -- Period: Ordovician
Image Use creative commons This media file is licensed under the Creative Commons Attribution License - Version 3.0.
Copyright © 1997
Attached to Group Astraspida: view page image collection
Title astraspida.gif
Image Type Drawing/Painting
Image Content Specimen(s)
ID 713
722
Scientific Name Tauraspis, Hoelaspis, Tremataspis, Zenaspis
Comments Osteostracans are known from the Silurian and Devonian of Europe, Siberia and North America. They are characterized by peculiar "cephalic fields" of unknown function, on the dorsal surface of the head-shield (red). Although jawless, they share with jawed vertebrates well-developed paired fins, an epicercal tail, cellular bone, and a sclerotic ring in eyes. Their mouth and gill opening are ventrally placed, as in galeaspids and pituriaspids. Their median, dorsal, nasohypophysial aperture, anterior to the eyes, is strikingly similar to that of lampreys but is now regarded as a convergence. All the osteostracans reconstructed here belong to the major clade Cornuata, whose generalized morphology is exemplified by the zenaspidid Zenaspis (bottom left). Some highly derived head-shield morphologies are exemplified by the benneviaspidids Hoelaspis (top right) and Tauraspis (top left), or the thyestiid Tremataspis (bottom right). The latter has lost the paired fins, possibly as a consequence of an adaptation to burrowing habits.
Reference based on Janvier, P. 1985. Les Céphalaspides du Spitsberg. Anatomie, phylogénie et systématique des Ostéostracés siluro-dévoniens. Révision des Ostéostracés de la Formation de Wood Bay (Dévonien inférieur du Spitsberg). Cahiers de Paléontologie, Centre national de la Recherche scientifique, Paris. AND Janvier, P. 1985. Les Thyestidiens (Osteostraci) du Silurien de Saaremaa (Estonie). Première partie: Morphologie et anatomie, Annales de Paléontologie, 71(2), p.83-147. Deuxième partie: Analyse phylogénétique, répartition stratigraphique, remarques sur les genres Auchenaspis, Timanaspis, Tyriaspis, Didymaspis, Sclerodus et Tannuaspis. Annales de Paléontologie, 71(3), p.187-216. AND Mark-Kurik, E. & Janvier, P. 1995. Early Devonian osteostracans from Severnaya Zemlya, Russia. Journal of Vertebrate Paleontology. 15(3):449-462.
Image Use creative commons This media file is licensed under the Creative Commons Attribution License - Version 3.0.
Copyright © 1997
Attached to Group Osteostraci: view page image collection
Title osteostraci.gif
Image Type Drawing/Painting
Image Content Specimen(s)
ID 722
1056
Comments The craniates are characterized by a skull; that is, a complex ensemble of skeletal elements which surrounds the brain and sensory capsules. The skull of hagfishes (top) consists of cartilaginous bars (blue), but the brain is mostly surrounded by a fibrous sheath (yellow) underlain by the notochord (green). The skull of lampreys (middle) has a more elaborate braincase and comprises a large "branchial basket" surrounding the gills. In the gnathostomes (bottom), the braincase is generally closed (after Janvier 1996b).
Reference after Janvier, P. (1996). Early Vertebrates. Oxford Monographs in Geology and Geophysics, 33, Oxford University Press, Oxford.
Body Part skull
Image Use creative commons This media file is licensed under the Creative Commons Attribution License - Version 3.0.
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Attached to Group Craniata: view page image collection
Title craniata.gif
Image Type Drawing/Painting
Image Content Body Parts
ID 1056
1808
Comments Anaspids are characterized by a large, tri-radiate spine (red) posteriorly to the series of branchial openings. Typical anaspids are restricted to the Silurian but some doubtful forms occur in the Late Devonian. It is assumed that the most primitive anaspids, such as Pharyngolepis (top), possessed a long, ribon-shaped, ventrolateral fin-fold (green). More advanced forms, such as Rhyncholepis (bottom), possessed a shorter paired fin-fold (green) and enlarged, spine-shaped, median dorsal scutes.
Reference after Ritchie, A. (1964). New light on the morphology of the Norwegian Anaspida. Skrifter utgitt av det Norske Videnskaps-Akademi, 1, Matematisk-Naturvidenskapslige Klasse, 14, 1-35. and Ritchie, A. (1980). The Late Silurian anaspid genus Rhyncholepis from Oesel, Estonia, and Ringerike, Norway. American Museum Novitates, 2699, 1-18.
Specimen Condition Fossil
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Copyright © 1997
Attached to Group Anaspida: view page image collection
Title anaspida.gif
Image Type Drawing/Painting
Image Content Specimen(s)
ID 1808
1895 Hippopotamus with mouth wide open
Scientific Name Hippopotamus amphibius
Location Okavango Delta of Botswana
Sex Male
Body Part head
Copyright © 1997 Greg and Marybeth Dimijian
Image Use ToL use only
Attached to Group Hippopotamus amphibius (Hippopotamidae): view page image collection
Title 01035hippo.jpg
Image Type Photograph
Image Content Specimen(s)
ALT Text Hippopotamus with mouth wide open
ID 1895
2241
Comments Galeaspids are characterized by a large, median dorsal inhalent opening (red arrow).
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Copyright © 1997
Attached to Group Galeaspida: view page image collection
Title opening.gif
Image Type Drawing/Painting
Image Content Specimen(s)
ID 2241
2346
Scientific Name Homo sapiens
Acknowledgements The Digital Human Osteology Guide
Body Part skull
Copyright © 1997 John Kappelman
Image Use restricted
Attached to Group Craniata: view page image collection
Title skull.250.gif
Image Type Photograph
Image Content Specimen(s)
ID 2346
2367 Pterygolepis nitidus fossil
Scientific Name Pterygolepis nitidus
Location Norway
Specimen Condition Fossil -- Period: Lower Silurian
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Attached to Group Pterygolepis (Vertebrata): view page image collection
Title pterygolepis.jpeg
Image Type Photograph
Image Content Specimen(s)
ALT Text Pterygolepis nitidus fossil
ID 2367
2387
Comments Heterostracans are the most diverse group of pteraspidomorphs and lived during the Silurian and Devonian periods. Among the most primitive heterostracans are tolypelepids (top right). Most heterostracans are pteraspidiforms, such as the pteraspidids (bottom right), protopteraspidids (bottom left) and the huge psammosteids (top left), which are the youngest known members of the group.
Reference After Janvier 1996 AND Soehn, K. L. and Wilson, M. K. V. (1990). A complete, articulated heterostracan from Wenlockian (Silurian) beds of the Delorme Group, Mackenzie Mountains, Northwest territories, Canada. Journal of Vertebrate Paleontology, 10:405-419.
Specimen Condition Fossil
Image Use creative commons This media file is licensed under the Creative Commons Attribution License - Version 3.0.
Copyright © 1997
Attached to Group Protopteraspididae (Pteraspidomorphi): view page image collection
Pteraspididae (Pteraspidomorphi): view page image collection
Tolypelepidida (Heterostraci): view page image collection
Psammosteidae (Pteraspidomorphi): view page image collection
Title heterostraci.gif
Image Type Drawing/Painting
Image Content Specimen(s)
ID 2387
2486
Comments The vertebrates are characterized by a vertebral column; that is, a variable number of endoskeletal elements aligned along the notochord (green) and flanking the spinal cord (yellow). In lampreys (top), the vertebral elements are only the basidorsal (red) and the interdorsals (blue). In the gnathostomes, there are in addition ventral elements, the basiventrals (purple) and interventrals (orange), and the notochord may calcify into centra (pink).
Reference After Janvier, P. (1996). Early vertebrates. Oxford Monographs in Geology and Geophysics, 33, Oxford University Press, Oxford.
Body Part vertebral column
Image Use creative commons This media file is licensed under the Creative Commons Attribution License - Version 3.0.
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Attached to Group Vertebrata: view page image collection
Title vertebrata.gif
Image Type Drawing/Painting
Image Content Body Parts
ID 2486
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