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New avian records from the late Eocene of Antarctica (1 Viewer)

Fred Ruhe

Well-known member
Netherlands
Sarah N. Davis, Christopher R. Torres, Grace M. Musser, James V. Proffitt, Nicholas M.A. Crouch, Ernest L. Lundelius, Matthew C. Lamanna and Julia A. Clarke, 2020

New mammalian and avian records from the late Eocene La Meseta and Submeseta formations of Seymour Island, Antarctica

PeerJ. 8: e8268.
doi:10.7717/peerj.8268

Abstract and free pdf: https://peerj.com/articles/8268.pdf

The middlelate Eocene of Antarctica was characterized by dramatic change as the continent became isolated from the other southern landmasses and the Antarctic Circumpolar Current formed. These events were crucial to the formation of the permanent Antarctic ice cap, affecting both regional and global climate change. Our best insight into how life in the high latitudes responded to this climatic shift is provided by the fossil record from Seymour Island, near the eastern coast of the Antarctic Peninsula. While extensive collections have been made from the La Meseta and Submeseta formations of this island, few avian taxa other than penguins have been described and mammalian postcranial remains have been scarce. Here, we report new fossils from Seymour Island collected by the Antarctic Peninsula Paleontology Project. These include a mammalian metapodial referred to Xenarthra and avian material including a partial tarsometatarsus referred to Gruiformes (cranes, rails, and allies). Penguin fossils (Sphenisciformes) continue to be most abundant in new collections from these deposits. We report several penguin remains including a large spear-like mandible preserving the symphysis, a nearly complete tarsometatarsus with similarities to the large penguin clade Palaeeudyptes but possibly representing a new species, and two small partial tarsometatarsi belonging to the genus Delphinornis. These findings expand our view of Eocene vertebrate faunas on Antarctica. Specifically, the new remains referred to Gruiformes and Xenarthra provide support for previously proposed, but contentious, earliest occurrence records of these clades on the continent.

Enjoy,

Fred
 
SYSTEMATIC PALEONTOLOGY
MAMMALIA Linnaeus, 1758
EUTHERIA Gill, 1872
XENARTHRA Cope, 1889
Gen. et sp. indet.

Material TMM 44190-1, left metacarpal II.
Locality S124, Seymour Island, Antarctic Peninsula.
Formation/Age Cucullaea I Allomember (TELM 4), La Meseta Formation, late Eocene.

AVES Linnaeus, 1758
NEOGNATHAE Pycraft, 1900
GRUIFORMES Bonaparte, 1854 sensu Hackett et al., 2008
?GRUOIDEA Vigors, 1825 sensu Clarke, Norell & Dashzeveg, 2005
Gen. et sp. indet.

Material TMM 44189-2, distal end of left tarsometatarsus.
Locality S123, Seymour Island, Antarctic Peninsula.
Formation/Age Submeseta I Allomember (TELM 7), Submeseta Formation, late Eocene.

SPHENISCIFORMES Sharpe, 1891 sensu Clarke, Olivero & Puerta, 2003
Delphinornis sp.

Material TMM 44189-1, left tarsometatarsus.
Locality S123, Seymour Island, Antarctic Peninsula.
Formation/Age Submeseta I Allomember (TELM 7), Submeseta Formation, late Eocene.

Material TMM 44188-2, left tarsometatarsus.
Locality S122, Seymour Island, Antarctic Peninsula.
Formation/Age Submeseta I Allomember (TELM 7), Submeseta Formation, late Eocene.

Palaeeudyptes sp.

Material TMM 44188-1, left tarsometatarsus.
Locality S117, Seymour Island, Antarctic Peninsula.
Formation/Age Submeseta I Allomember (TELM 7), Submeseta Formation, late Eocene.

Gen. et sp. indet.

Material TMM 44187-1, rostral portion of mandible with associated fragments of caudal rami.
Locality S074, Seymour Island, Antarctic Peninsula.
Formation/Age Cucullaea II Allomember (TELM 5), La Meseta Formation, late Eocene.

Fred
 
Figure 1 Distal end of a left tarsometatarsus (TMM 44189-2) compared to those of extant gruiforms. The fossil (AE) and comparative materials (FY) shown in dorsal, plantar, medial, lateral, and distal views. Abbreviations: II, trochlea II; III, trochlea III; IV, trochlea IV; dvf, distal vascular foramen. Scale bar D 10 mm.

Figure 2 New sphenisciform fossil material. A small left tarsometatarsus (TMM 44189-1) in (A) dorsal, (B) plantar, (C) proximal, and (D) distal views; a small left tarsometatarsus (TMM 44188-2) in (E) dorsal, (F) plantar, (G) proximal, and (H) distal views; a large left tarsometatarsus (TMM 44188-1) in (I) dorsal, (J) plantar, (K) proximal, and (L) distal views; and a partial mandible (TMM 44187-1) in (M) dorsal, (N) ventral, (O) right (with associated material), and (P) left (with associated material) views. Abbreviations: II, trochlea II; III, trochlea III; dvf, distal vascular foramen; es, extensor sulcus; fs, flexor sulcus; h, hypotarsus; ia, intercotylar area; ie, intercotylar eminence; lc, lateral cotyla; mc, medial cotyla; ms, mandibular symphysis; pvf, proximal vascular foramen. Scale bar D 10 mm.

Fred
 

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