Abstract
The highly fossiliferous Eocene deposits of the Antarctic Peninsula are among the most productive sites for fossil remains in the Southern Hemisphere and offer rare insights into high-latitude faunas during the Palaeogene. Chondrichthyans, which are represented by abundant isolated remains, seemingly dominate the marine assemblages. Eocene Antarctic sawsharks have only been known from few isolated rostral spines up to now, that were assigned to Pristiophorus lanceolatus. Here, we present the first oral teeth of a sawshark from the Eocene of Seymour Island and a re-evaluation of previously described Pristiophorus remains from Gondwana consisting exclusively of rostral spines. The holotype of Pristiophorus lanceolatus represents a single, abraded and insufficiently illustrated spine from the Oligocene of New Zealand. All other Cenozoic rostral spines assigned to this species are morphologically very indistinct and closely resemble those of living taxa. Consequently, we regard this species as dubious and introduce a new species, Pristiophorus laevis, based on oral teeth. The combination of dental characteristics of the new species makes it unique compared to all other described species based on oral teeth. Rostral spines from the Eocene of Seymour Island are assigned to this new species whereas those from other Cenozoic Gondwana localities remain ambiguous.LSID urn:lsid:zoobank.org:pub:7177A373-527B-4315-85F6-25180DB5E087
Highlights
The family Pristiophoridae Bleeker, 1859 (Pristiophoriformes Berg, 1958) is an ancient group of squalomorph elasmobranchs with a fossil record extending back into the Early Cretaceous, some 110 Myr ago (Keyes 1982; Kemp 1991)
The purpose of this paper is to present the first unambiguous record of an extinct sawfish from the Southern Hemisphere, which is represented by isolated oral teeth and rostral spines from the Eocene of Antarctica
Most living sawshark species are restricted to the Indo-West Pacific (Figure 5), with Pristiophorus schroederi (Springer & Bullis 1960) which inhabits the western North Atlantic Pliotrema warreni (Regan 1906) and Pristiophorus nancyae (Ebert & Cailliet 2011), which are known from the western Indian Ocean being the exception (Compagno et al 2005)
Summary
The family Pristiophoridae Bleeker, 1859 (Pristiophoriformes Berg, 1958) is an ancient group of squalomorph elasmobranchs with a fossil record extending back into the Early Cretaceous, some 110 Myr ago (Keyes 1982; Kemp 1991) They are characterized by a dorso-ventrally flattened body and hypertrophied rostrum lined laterally by saw-teeth, which evolved convergently to the elongated and toothed rostrum in sawfishes of the family Pristidae Bonaparte, 1838 (Pristiformes Compagno, 1973) that belongs to batomorphs. While pristiophorids were distributed globally in the past, their modern-day occurrences are seemingly more restricted They are confined to the western North Atlantic, the south-eastern Atlantic, the western Indian Ocean, the Arabian Sea, and the western Pacific inhabiting continental and insular shelves, and upper slopes in temperate regions and deeper waters in the tropics (Compagno et al 2005). No species occurs in polar seas today (Ebert & Winton 2010)
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