RV-8200, Seymour Island (Eocene of Antarctica)

Where: Antarctica (64.2° S, 56.6° W)

• Paleocoordinates: 62.6° S, 66.3° W (Wright 2013)

• coordinate stated in text

• outcrop-level geographic resolution

When: Telm 5 Member (La Meseta Formation), Bartonian (41.0 - 37.7 Ma)

• From the lowest part of Telm5 or the Cucullaea I allomember. The age model for the La Meseta Formation (and recently-defined Submeseta Formation) is controversial. Strontium isotopes (Ivany et al., 2008) suggest earlier ages, with the La Meseta (Telm1-Telm5) almost entirely Ypresian and the Submeseta (Telm6-Telm7) Middle-Late Eocene. Montes et al. (2013) also created an age model incorporating magnetostratigraphy to support the largely-Ypresian age for the La Meseta and Middle-Late Eocene for the Submeseta. Some mammals are similar to the radiometrically-constrained late early Eocene Paso del Sapo assemblage of Patagonia (Gelfo et al., 2009, Tejedor et al., 2009), but the mammals are not exactly similar (Bond et al., 2011). However, Douglas et al. (2014) re-evaluated the strontium data and used dinoflagellate biostratigraphy to argue for a Lutetian (Telm2-4) and younger (Bartonian to mid-Priabonian for Telm5-6) age range. Amenábar et al. (2020) also found younger ages from dinoflagellates: Lutetian (Telm1-mid Telm 3), Bartonian (mid Telm 3-mid Telm 5), and Priabonian (upper Telm 5), SPDZ10-SPDZ13. This age range is more consistent with the presence of basilosaurid whales in Telm4 and Telm7, as basilosaurids are globally-distributed first in the middle Eocene (Buono et al., 2016). Although the ages are still debated, the dinoflagellate age model of Amenábar et al. (2020) is used here.

• group of beds-level stratigraphic resolution

Environment/lithology: paralic; burrowed, silty sandstone and poorly lithified, concretionary, shelly/skeletal sandstone

• The environment of deposition of this complex unit has been subject to different interpretations, all agreeing in general that Telm5 represents a shallow-marine setting. A study by Wiedman and Feldmann (1988) on the ichnofossil fauna and depositional environment of the La Meseta Formation concluded that the Telm5 setting was a littoral to very shallow sublittoral clastic marine terrain, definitely above storm base and most probably above normal wave base. They agreed with Elliot and Trautrnan (1982) that Units II and III probably represent a tidally dominated environment, but evidence from sedimentary structures is also consistent with a barrier bar model and does not represent a shallowing upward sequence. Elliot and Trautman (1982) favored a deltaic model. The analysis of trace fossils and body fossils (including vertebrate remains and large, abundant wood fragments) indicates variable nearshore, shallow-marine environments. A scenario for the depositional environment could include a combination ebb-tidal (or possibly flood-tidal) delta-barrier island complex (Stilwell & Zinsmeister, 1992).
• Finely laminated beds of silty sandstone, some of which are interbedded with pebbly conglomeratic units interpreted to represent shell banks. The finer-grained beds between the shell banks are finely laminated, and exhibit ripple marks and flaser bedding. Vertical and oblique burrows are common throughout the finer-grained units. Small to large cut-and-fill channel features occur within the sandy siltstone facies. Prominent slump structures and lenses of gravel are associated with these channels. The shell banks consist of individual beds that range in thickness from .5 to 2m, and extend laterally as much as 1km. The banks are characterized by coarse- to fine-grained, well-sorted arkosic sandstone beds that contain pebble- to cobble-sized clasts. Most of the shell banks are extremely fossiliferous.

Size classes: macrofossils, mesofossils

Collection methods: sieve,

• Repository: University of California, Riverside

Primary reference: M. O. Woodburne and W. J. Zinmeister. 1982. Fossil Land Mammal from Antarctica. Science 218:284-286 [J. Alroy/E. Leckey/E. Leckey]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 31173: authorized by John Alroy, entered by Erin Leckey on 15.04.2003, edited by Mark Uhen and Matthew Clapham

Creative Commons license: CC0 (CC0)

Taxonomic list

Cephalopoda
 Nautilida - Nautilidae
"Eutrephoceras argentinae" = Euciphoceras argentinae12
"Eutrephoceras argentinae" = Euciphoceras argentinae12 Del Valle and Fourcade 1976
 Nautilida - Aturiidae
Aturia sp.12 Bronn 1838
Reptilia
  -
Reptilia indet. Laurenti 1768 reptile
 Testudines -
"Chelonia indet." = Testudines
"Chelonia indet." = Testudines Batsch 1788 turtle
Aves
  -
Aves indet. Linnaeus 1758 bird
 Neornithes -
Sphenisciformes indet. penguin
penguins
Mammalia
 Tribosphenida -
Metatheria indet. Huxley 1880 metatherian
 Polydolopimorphia - Polydolopidae
Antarctodolops sp.2, "Antarctodolops dailyi n. gen. n. sp." = Antarctodolops dailyi11, "Eurydolops seymourensis n. gen. n. sp." = Antarctodolops dailyi1
Antarctodolops sp.2 Woodburne and Zinsmeister 1984 metatherian
UCR 20913, an isolated left M2. Could be _A. dailyi_, _A. mesetaense_, or a third species.
"Antarctodolops dailyi n. gen. n. sp." = Antarctodolops dailyi11 metatherian
"Eurydolops seymourensis n. gen. n. sp." = Antarctodolops dailyi1 metatherian
isolated left P3
 Tribosphenida -
Eutheria indet. eutherian
"probably marine placental mammal"
Osteichthyes
 Labriformes - Labridae
Labridae indet.8 Cuvier 1816 ray-finned fish
 Teleostei -
Teleostei indet. ray-finned fish
vertebrae and teeth of fish
Chondrichthyes
 Elasmobranchii -
Elasmobranchii indet.5 Bonaparte 1838 elasmobranch
Elasmobranchii indet.4 Bonaparte 1838 elasmobranch
 Lamniformes - Otodontidae
"Carcharocles auriculatus" = Otodus auriculatus7
"Carcharocles auriculatus" = Otodus auriculatus7 Blainville 1818 mackerel shark
 Lamniformes - Odontaspididae
Odontaspis winkleri7 Leriche 1905 sand tiger shark
Brachycarcharias lerichei9 Casier 1946 sand tiger shark
"Odontaspis rutoti" = Palaeohypotodus rutoti7 Winkler 1878 sand tiger shark
 Orectolobiformes - Hemiscylliidae
Notoramphoscyllium woodwardi5 Engelbrecht et al. 2016 carpet shark
Stegostoma cf. varium in table
 Squaliformes - Centrophoridae
Centrophorus sp.7 Müller and Henle 1837 gulper shark
 Squaliformes - Dalatiidae
Eodalatias austrinalis6 Engelbrecht et al. 2017 elasmobranch
 Squaliformes - Squalidae
Squalus woodburnei n. sp.7 Long 1992 dogfish shark
Squalus weltoni n. sp.7 Long 1992 dogfish shark
 Hexanchiformes - Hexanchidae
Hexanchidae indet.7 Gray 1851 cow shark
 Pristiophoriformes - Pristiophoridae
Pristiophorus laevis3 Engelbrecht et al. 2017 saw shark
 Squatiniformes - Squatinidae
Squatina sp.7 Dumeril 1806 angel shark
 Chimaeriformes - Callorhynchidae
Ischyodus dolloi10 Leriche 1902 plownose chimaera
Angiospermae
 Fagales - Nothofagaceae
Nothofagus sp.2 Blume 1850
leaf impressions and carbon films