Product: 075 Silurian and Lower Devonian thelodonts and putative chondrichthyans from the Canadian Arctic Archipelago

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Special papers in Plaeaeontology 75.
<br />
<br />Silurian and Lower Devonian thelodonts and putative chondrichthyans from the Canadian Arctic Archipelago.
<br />
<br />T. Marss, M.V.H. Wilson and R. Thorsteinsson.
<br />
<br />143pp., 29pls
<br />
<br />ABSTRACT: Thelodonts and putative chondrichthyans from
<br />rocks of upper Llandovery (Lower Silurian) to Lochkovian
<br />(Lower Devonian): mainly from Baillie-Hamilton and Cornwallis islands, Arctic Canada, are treated according to taxonomic content, spatio-temporal distribution, and possible
<br />significance for recognition of geological event levels. The systematics of numerous groups of thelodonts can, for the first time, be based on both articulated specimens and isolated scales. Some 39 thelodont species ( 12 of them preserved as
<br />articulated squamations) belonging to 25 genera, 16 families, and five orders, together with two putative chondrichthyan taxa (both represented by articulated squamations) are treated.
<br />
<br />The thelodont order Loganelliiformes Turner, contains herein the family Loganelliidae
<br />Karatajut??-Talimaa, with the genera Loganellia Turner, represented by L. scotica (Traquair), L. sulcata M??rss et al., L. prolata M??rss et al., L. grossi
<br />Fredholm, and L. exilis M??rss et al., and Illoganellia M??rss
<br />et al., including f. colossea M??rss et al., and the family
<br />Nunavutiidae M??rss et al., with the genus Nunavutia Marss
<br />et al., comprising N. fasciata M??rss et al.
<br />
<br />The order Shieliiformes M??rss et al. includes the family Shieliidae M??rss et al., with the genus Shielia Marss, represented
<br />by S. parca M??rss et al. and S. gibba M??rss et al., along with
<br />the genus Paralogania Karatajut??-Talimaa, incorporating
<br />P. martinssoni (Gross) and P. readbayensis Marss et al.
<br />The order Phlebolepidiformes Berg comprises the family
<br />Phlebolepididae Berg, with the genus Erepsilepis M??rss et al.
<br />with its species E. margaritifera M??rss et al.., and the family
<br />Katoporodidae M??rss et al., with the genera Katoporodus
<br />Turner and Peel, represented by K. tricavus (Gross), K serratus M??rss et al., and K. gemellus M??rss et al., Overia Soehn
<br />et al., containing O. adraini Soehn et al., and Goniporus
<br />Gross, characterized by G. alatus (Gross).
<br />
<br />The order Thelodontiformes Kiaer includes the family Coelolepididae Pander, with the genus Tbelodus Agassiz, represented by T. inauditus M??rss et al. and Thelodus? sp. indet. The family Lanarkiidae Obruchev contains the genera Lanarkia Traquair, exemplified by L. horrida Traquair and Lanarkia? sp.,
<br />and Phillipsilepis M??rss et al., characterized by P. crassa M??rss
<br />et al., P cornuta M??rss et al., and P pusilla Mtirss et al. The
<br />family Archipelepididae M??rss, in Soehn et al., has one genus,
<br />Archipelepis M??rss (in Soehn et al.), with one species, A. bifurcata Marss et al. The family Boothialepididae M??rss contains
<br />the genus Boothialepis M??rss, represented by B. thorsteinssoni
<br />M??rss. The family Turiniidae Obruchev comprises the genus
<br />Turinia Traquair with the species T. polita Karatajut??-Talimaa.
<br />The family Nikoliviidae Karatajut??-Talimaa includes the genera
<br />Nikolivia Karatajut??-Talimaa, represented by N. gutta Karatajut??-Talimaa and N. auriculata M??rss et al., and Chattertonodus M??rss et al., represented by C cometoides M??rss et al.
<br />
<br />The family Talivaliidae M??rss et al. embraces the genera Talivalia
<br />M??rss et al., represented by T. elongata ( Karatajut??-Talimaa):
<br />and Glacialepis M??rss et al. with G. corpulenta Marss et al.
<br />Questionably assigned to the order Thelodontiformes is the
<br />family Eestilepididae Marss et al., with one genus, Eestilepis
<br />M??rss et al., represented by F. prominens M??rss et al.
<br />The order Furcacaudiformes Wilson and Caldwell, occurs in
<br />the sections studied as the family Furcacaudidae Wilson and
<br />Caldwell, with the genus Canonia Vieth comprising three species: C. grossi Vieth, C. costulata Marss et al. and Canonia? sp.
<br />
<br />Questionably assigned to the order Furcacaudiformes is
<br />the family Barlowodidae M??rss et al., with the genera
<br />Barlowodus M??rss et al., containing B. excelsus M??rss et al.,
<br />B. floralis M??rss et al., and B. tridens Marss et al., and Sophialepis M??rss et al., represented by S. ancorata M??rss et al.
<br />Taxa of putative chondrichthyans of uncertain ordinal position comprise the family Kannathalepididae Marss and Gagnier, with the genus Frigorilepis M??rss et al., including F. caldwelli M??rss et al. , along with the family Wellingtonellidae M??rss et al., with the genus Wellingtonella Marss et al.,
<br />represented by W. gagnieri M??rss et al.
<br />
<br />Both taxonomic and morphological diversity of thelodonts
<br />is much greater than previously known; new anatomical
<br />information will allow greater precision in future phylogenetic
<br />studies of thelodonts and related vertebrates. Biostratigraphic
<br />distribution of taxa allows improved correlation of strata
<br />between Europe, the Canadian Arctic islands, and the Mackenzie Mountains, and greater precision in identification of
<br />the Llandovery/Wenlock boundary and the associated
<br />carbon-isotope excursion event.