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La Meseta Formation
The La Meseta Formation is a sedimentary sequence deposited during the Eocene on Seymour Island off the coast of the Antarctic Peninsula. It is noted for its fossils, which include both marine organisms and the only terrestrial vertebrate fossils from the Cenozoic of Antarctica.

Description

La Meseta Formation lies unconformably on the Cretaceous Lopez de Bertodano Formation. It is an approximately 557 metres (1,827 ft) thick sequence of poorly consolidated sandstones and siltstones. The depositional environment was probably coastal, deltaic or estuarine in character. The top of the sequence is an erosional unconformity to Pleistocene glacial gravels. La Meseta Formation is one of the sequences that make up the fill of the Late Jurassic to Paleogene James Ross Basin.

Paleoenvironment

The terrestrial environment surrounding the deposition area is thought to have been a temperate polar forest, including podocarp and araucarian conifers, as well as Nothofagus. Most of the fossilized woods and flowers discovered on Seymour Islands consist of extinct species of conifer trees and lilies during warm climate.

Paleobiota

La Meseta Formation is extremely rich in fossils. Among mammals, the meridiungulata Antarctodon and Trigonostylops have been found in the formation. as well as marsupial Derorhynchidae, Microbiotheria, and polydolopimorphia. It is famous for its penguin fossils, for example the two genera Archaeospheniscus and Palaeeudyptes. Other bird fossils include Dasornis, a genus of pseudotooth birds. There is also an abundance of trace fossils. Diplocraterion, Helminthopsis, Muensteria, Oichnus, Ophiomorpha, Skolithos, Teredolites and Zapfella have been described. Over 35 species and 26 families of fish, which includes sharks, have been described from the Ypresian Cucullaea bed.

Mammals

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Meriduingulata

Astrapotheria
Taxa Species Locality Stratigraphic position Material Notes Images
Antarctodon A. sobrali Locality DVP 2/84 and IAA 1/90. Cucullaea I allomember (Telm 5). MLP 08-XI-30-1, an isolated right p4 or m1. An astrapothere
Trigonostylops T. indet. Cucullaea I allomember (Telm 5). An astrapothere
Litopterna
Taxa Species Locality Stratigraphic position Material Notes Images
Notiolofos N. arquinotiensis Locality IAA 1/13 and DPV 16/84. Acantilados II, Campamento, Cucullaea I Allomember (Telm 4) and Submeseta Member (Telm 7). A Brachyodont lower right molar fragment, probably m1 or m2, preserves a portion of the talonid with most of the lingual side (MLP 13-I-25-1) and left M3 incomplete (MLP 95-I-10-6). A sparnotheriodontid litoptern.
N. regueroi Locality IAA 2/16 Lower coquina bed of Cucullaea I Allomember. IAA-PV 173, Isolated complete left m3.
Victorlemoinea V. sp. Cucullaea I allomember (Telm 5). A sparnotheriodontid litoptern.

Cetacean

Taxa Species Locality Stratigraphic position Material Notes Images
Basilosaurus undetermined
Llanocetus L. denticrenatus Locality DPV 10/84 and DVP 13/24. Unit III Member and Telm 7. A partial mandible with two teeth (specimen USNM 183022) and an endocast of the braincase. a toothed baleen whale.
Zygorhiza undetermined

Metatherians

Derorhynchidae
Taxa Species Locality Stratigraphic position Material Notes Images
Derorhynchus D. minutus Locality IAA 1/90. Allomember Cucullaea I (Telm 5). MLP 96-1-5-44, incomplete right horizontal ramus of the dentary fragment with m2-3.
Pauladelphys P. juanjoi Locality IAA 2/95 and IAA 1/90. Allomember Cucullaea I (Telm 5). An isolated lower molar (MLP 95-1-10-2) and an upper left molar (MLP 96-1-5-44).
Xenostylos X. peninsularis Locality IAA 1/90. Allomember Cucullaea I (Telm 5). MLP 94-111-15-10, an isolated upper right molar.
Microbiotheria
Taxa Species Locality Stratigraphic position Material Notes Images
Marambiotherium M. glacialis Locality IAA 1/90 and RV-8200. Cucullaea I allomember (Telm 5). MLP 95-1-10-1, a fragment of a right mandibular ramus with a complete m4 and the posterior alveolus of m3 and MLP 88-1-1-1, an edentulous left mandibular ramus with the alveoli for p3-m4. Members of Microbiotheria
Woodburnodon W. casei Locality IAA 1/95. Cucullaea I allomember (Telm 5). MLP 04-III-1-2, an isolated, worn upper right molar (M2 or M3).
Polydolopimorphia
Taxa Species Locality Stratigraphic position Material Notes Images
Antarctodolops A. dailyi Locality IAA 2/95, DPV 2/84, and DPV 6/84. Cucullaea I allomember (Telm 5). UCR 20910, a left dentary with p3-m2. A polydolopimorphian metatherian.
A. mesetaense Locality IAA 1/90 and DPV 6/84. Cucullaea I allomember (Telm 5). Right dentary fragments.
Perrodelphys P. coquinense Locality IAA 1/90. Cucullaea I allomember (Telm 5). MLP 96-1-5-11, an isolated left lower molar. A polydolopimorphian metatherian.
Polydolops P. dailyi Locality IAA 1/90 & DPV 3/84. Cucullaea I allomember (Telm 5). A polydolopimorphian metatherian.
P. seymouriensis Locality IAA 1/90 & DPV 3/84. Cucullaea I allomember (Telm 5).
P. thomasi Locality IAA 1/90 & DPV 3/84. Cucullaea I allomember (Telm 5).
Pujatodon P. ektopos Locality IAA 1/90. Cucullaea I Allomember (Telm 5). Specimen MLP 14-I-10-20, a lower left molar (m2 or m3) partially worn. A polydolopimorphian metatherian.

Other mammals

Taxa Species Locality Stratigraphic position Material Notes Images
Sudamerica S. ameghinoi Locality IAA 1/90 upper level. Cucullaea I Allomember. MLP 95-I-10-5, anterior part of a left dentary with the rodent-like incisor partially preserved. A gondwanathere
Meridiolestida? Indeterminate Locality IAA 1/90 upper level. Cucullaea I Allomember. A single tooth, now lost.
Xenarthra? Indeterminate. Locality S124. Cucullaea I Allomember/ Telm 4. TMM 44190-1, left metacarpal II and A phalanx and a partial tooth

Birds

Sphenisciformes

Taxa Species Locality Stratigraphic position Material Notes Images
Anthropornis A. grandis Locality IAA 4/12, IAA 1/90, DPV 13/84, and DVP 2/84. Telm 4 member, Telm 7 member, and Submeseta Allomember. Humerus: MLP 93-X-1-4 (proximal epiphysis), MLP 82-IV-23-4 (proximal epiphysis), MLP 83-I-1-190(proximal epiphysis) and MLP 88-I-1-463(proximal epiphysis). Relatives of giant penguins.
A. nordenskjoldi Submeseta Allomember. Humerus: MLP CX-60-25 (proximal epiphysis), MLP 83-V-30-5 (diaphysis) and MLP 93-X-1-104(complete humerus).
Archaeospheniscus A. lopdelli Submeseta Allomember. Relatives of giant penguins
A. wimani Submeseta Allomember.
Delphinornis D. arctowskii DPV 14/84 Cucullaea I Allomember (Telm 7).
D. graclis DPV 14/84 Cucullaea I Allomember (Telm 7).
D. larseni DPV 13/84 and DPV 14/84. Cucullaea I Allomember (Telm 5 and Telm 7) and Submeseta Allomember.
Marambiornis M. exilis DVP 2/84, IAA 1/12, and ZPAL 4 Telm 7 Member. A limb element (right tarsometatarsus). An early relative of penguin.
Mesetaornis M. polaris Telm 7 member. A nearly complete right femur and two distal left tibiotarsi.
Orthopteryx O. gigas
Palaeeudyptes P. antarcticus Cucullaea I Allomember (Telm 3, Telm 4, Telm 5, and Telm 7) and Submeseta Allomember. The narrow-flippered penguin.
P. gunnari DVP 2/84, DVP 10/84, DVP 13/84, DVP 14/84, DVP 15/84, and ZPAL 4. Cucullaea I Allomember (Telm 3, Telm 5, and Telm 7) and Submeseta Allomember. Multiple specimens consist of coracoids, ulna, and humerus.
P. klekowskii DVP 2/84, DVP 10/84, DVP 13/84, DVP 14/84, DVP 16/84, and ZPAL 4. Cucullaea I Allomember (Telm 3, Telm 5, and Telm 7) and Submeseta Allomember. Several specimens consist of humerus, coracoid, ulna, and tibiotarsus.
Wimanornis W. seymourensis DPV 14/84. Cucullaea I Allomember (Telm 7) and Submeseta Allomember.
Tonniornis T. mesetaensis DPV 14/84. Cucullaea I Allomember (Telm 7) and Submeseta Allomember.
T. minimum DPV 14/84. Cucullaea I Allomember (Telm 7) and Submeseta Allomember.

Other birds

Taxa Species Locality Stratigraphic position Material Notes Images
Antarctoboenus A. carlinii IAA 2/95 locality Cucullaea I Allomember MLP 95-I-10-8, distal end of left tarsometatarsus A stem Falconiform
Dasornis D. sp. A pseudotooth bird
Phorusrhacidae? Indeterminate. Locality IAA 2/13 Cucullaea I Allomember A right ungual phalanx (MLP-PV 13-XI-28-546) and an incomplete ungual phalanx (MLP-PV 14-I-10-199) A large flightless cariamiform bird

Amphibians

Taxa Species Locality Stratigraphic position Material Notes Images
Calyptocephalella C. sp. Locality IAA 2/95. Cucullaea I Allomember (Telm 5). The fragmentary right ilium (NRM-PZ B282) and a skull bone (NRM-PZ B281). Calyptocephalellid frog

Fish

Chondrichthyes

Carcharhinidae
Taxa Species Locality Stratigraphic position Material Notes Images
Scoliodon S. sp. Multiple teeth. A requiem shark.
Hexanchidae
Taxa Species Locality Stratigraphic position Material Notes Images
Heptranchias H. howellii Upper lateral teeth. Relatives of sevengill sharks.
Hexanchus H. sp.
Lamnidae
Taxa Species Locality Stratigraphic position Material Notes Images
Isurus I. praecursor
Lamna L. cf. nasus
Otodus O. auriculatus
Mitsukurinidae
Taxa Species Locality Stratigraphic position Material Notes Images
Anomotodon A. multidenticulata An extinct relative of goblin shark.
Odontaspididae
Taxa Species Locality Stratigraphic position Material Notes Images
Odontaspis O. rutoti Relatives of sand shark.
O. winkleri
Striatolamia S. macrota An early relative of sand shark.
Orectolobidae
Taxa Species Locality Stratigraphic position Material Notes Images
Stegostoma S. cf. varium
Pseudoginglymostoma P. cf. P. brevicaudatum
Pristiophoridae
Taxa Species Locality Stratigraphic position Material Notes Images
Pristiophorus P. lanceolatus
P. laevis
Squalidae
Taxa Species Locality Stratigraphic position Material Notes Images
Squalus S. weltoni UCR RV-8200, Telm 4. Lower A complete lateral tooth. An early dogfish relative.
S. woodburnei UCR RV-8200, Telm 4. Lower. A complete lateral tooth.

Actinopterygii

Xiphiidae
Taxa Species Locality Stratigraphic position Material Notes Images
Xiphiorhynchus X. cf. sp.
Notothenioids
Taxa Species Locality Stratigraphic position Material Notes Images
Mesetaichthys M. jerzmanskae Fragmentary skull bones and vertebra. An early member of the Notothenioidei, the dominant marine fish of Antarctica today. Initially assigned to the Gadiformes.

Cephalopods

Taxa Species Locality Stratigraphic position Material Notes Images
Antarcticeras A. nordenskjoeldi NRM 8, below IAA 1/90 (Ungulate Site). Cucullaea I shell bed, Telm 4. A fragmentary preserved straight shell. An enigmatic cephalopod that is either considered a descendant of the orthocerids or an oegopsid squid.
Euciphoceras E. sp. NRM 8, below IAA 1/90 (Ungulate Site). Cucullaea I shell bed, Telm 4. A fragmentary preserved straight shell. A nautiloid.

Plants

Taxa Species Locality Stratigraphic position Material Notes Images
Agathoxylon A. pseudoparenchymatosum Locality 5 Cucullaea I allomember Fossilized wood.
fossilized seed of Notonuphar
Cupressinoxylon C. hallei Localities 4, 5, 6 and 7. Campamento and Cucullaea I allomember. Fossilized wood.
Notonuphar N. antarctica IAA 2/95. Cucullaea I Allomember (Telm 5). Fossilized seeds. A water lily.
Nelumbo ? Nelumbo sp.
Protophyllocladoxylon P. francisiae
Phyllocladoxylon P. antarcticum
P. pooleae

See also

References

  1. ^ Zinsmeister, Jeffrey D. Stilwell ; William J. (1992). Molluscan systematics and biostratigraphy : Lower Tertiary La Meseta Formation, Seymour Island, Antarctic Peninsula. Washington, DC: American Geophysical Union. ISBN 978-0875907703.{{cite book}}: CS1 maint: multiple names: authors list (link)
  2. ^ Pezzetti, T.F.; KRISSEK, L.A (1986). "Re-evaluation of the Eocene La Meseta Formation of Seymour Island, AntarcticPeninsula": 75. {{cite journal}}: Cite journal requires |journal= (help)
  3. ^ Reguero, Marcelo A.; Sergio A. Marenssi; Sergio N. Santillana (2012). "Weddellian marine/coastal vertebrates diversity from a basal horizon (Ypresian, Eocene) of the Cucullaea I Allomember, La Meseta formation, Seymour (Marambio) Island, Antarctica". Rev. Peru. Biol. 19 (3): 275–284. doi:10.15381/rpb.v19i3.1006.
  4. ^ Vega, Greta C.; Olalla-Tárraga, Miguel Ángel (2020), "Past changes on fauna and flora distribution", Past Antarctica, Elsevier, pp. 165–179, doi:10.1016/b978-0-12-817925-3.00009-4, ISBN 978-0-12-817925-3, retrieved 2023-09-20
  5. ^ Pujana, Roberto R.; Santillana, Sergio N.; Marenssi, Sergio A. (January 2014). "Conifer fossil woods from the La Meseta Formation (Eocene of Western Antarctica): Evidence of Podocarpaceae-dominated forests". Review of Palaeobotany and Palynology. 200: 122–137. Bibcode:2014RPaPa.200..122P. doi:10.1016/j.revpalbo.2013.09.001. hdl:11336/17151.
  6. ^ Reguero, Marcelo A.; Marenssi, Sergio A.; Santillana, Sergio N. (May 2002). "Antarctic Peninsula and South America (Patagonia) Paleogene terrestrial faunas and environments: biogeographic relationships". Palaeogeography, Palaeoclimatology, Palaeoecology. 179 (3–4): 189–210. Bibcode:2002PPP...179..189R. doi:10.1016/S0031-0182(01)00417-5.
  7. ^ Pujana, R. R., Wilf, P., & Gandolfo, M. A. (2020). Conifer wood assemblage dominated by Podocarpaceae, early Eocene of Laguna del Hunco, central Argentinean Patagonia. PhytoKeys, 156, 81–102. https://doi.org/10.3897/phytokeys.156.54175
  8. ^ Friis, Else M.; Iglesias, Ari; Reguero, Marcelo A.; Mörs, Thomas (2017-08-01). "Notonuphar antarctica, an extinct water lily (Nymphaeales) from the Eocene of Antarctica". Plant Systematics and Evolution. 303 (7): 969–980. Bibcode:2017PSyEv.303..969F. doi:10.1007/s00606-017-1422-y. ISSN 2199-6881. S2CID 254058613.
  9. ^ Antarctodon at Fossilworks.org
  10. ^ Trigonostylops at Fossilworks.org
  11. ^ Chornogubsky, L. (2009). A Reassessment of Antarctic Polydolopid Marsupials (Middle Eocene, La Meseta Formation). Antarctic Science.
  12. ^ Goin, F. J.; Zimicz, N.; Reguero, M. A.; Santillana, S. N.; Marenssi, S. A.; Moly, J. J. (October 2007). "New marsupial (Mammalia) from the Eocene of Antarctica, and the origins and affinities of the Microbiotheria". Revista de la Asociación Geológica Argentina. 62 (4): 597–603. ISSN 1851-8249. Retrieved 2017-02-12.
  13. ^ Tambussi, Claudia & Acosta Hospitaleche, Carolina & Reguero, Marcelo & Marenssi, Sergio. (2006). Late Eocene penguins from West Antarctica: Systematics and biostratigraphy. Geological Society London Special Publications. 258. 145-161. 10.1144/GSL.SP.2006.258.01.11.
  14. ^ Hospitaleche, C. A., & Reguero, M. (2011). Taxonomic status of the Eocene penguinsOrthopteryx gigasWiman, 1905 andIchtyopteryx gracilisWiman, 1905 from Antarctica. Alcheringa: An Australasian Journal of Palaeontology, 35(3), 463–466. https://doi.org/10.1080/03115518.2011.527476
  15. ^ Uchman, Alfred; Andrzej GAŹDZICKI (2006). "New trace fossils from the La Meseta Formation (Eocene) of Seymour Island, Antarctica". Pol. Polar Res. 27: 153–170.
  16. ^ Long, Douglas. (1992). Sharks from the La Meseta Formation (Eocene), Seymour Island, Antarctic Peninsula. Journal of Vertebrate Paleontology. 12. 11-32. 10.1080/02724634.1992.10011428.
  17. ^ Goin, Francisco J. New Discoveries of "Opposum [sic]-Like" Marsupials from Antarctica (Seymour Island, Medial Eocene). OCLC 1196811246.
  18. ^ "Antarctic Paleontological Heritage: Late Cretaceous–Paleogene vertebrates from Seymour (Marambio) Island, Antarctic Peninsula". Advances in Polar Science. 30. 20 August 2019. doi:10.13679/j.advps.2019.0015.
  19. ^ Francisco J. Goin; Emma C. Vieytes; Javier N. Gelfo; Laura Chornogubsky; Ana N. Zimicz; Marcelo A. Reguero (2020). "New metatherian mammal from the early Eocene of Antarctica". Journal of Mammalian Evolution. 27 (1): 17–36. doi:10.1007/s10914-018-9449-6. S2CID 91932037.
  20. ^ Gelfo, Javier N.; Goin, Francisco J.; Bauzá, Nicolás; Reguero, Marcelo (30 September 2019). "The fossil record of Antarctic land mammals: Commented review and hypotheses for future research". Advances in Polar Science: 274–292. doi:10.13679/j.advps.2019.0021.
  21. ^ Cenizo, Marcos; Noriega, Jorge I.; Reguero, Marcelo A. (2016-01-12). "A stem falconid bird from the Lower Eocene of Antarctica and the early southern radiation of the falcons". Journal of Ornithology. 157 (3): 885–894. doi:10.1007/s10336-015-1316-0. hdl:11336/54190. ISSN 2193-7192.
  22. ^ Acosta Hospitaleche, Carolina; Jones, Washington (2024). "Were terror birds the apex continental predators of Antarctica? New findings in the early Eocene of Seymour Island". Palaeontologia Electronica. 27 (1): 1–31. doi:10.26879/1340.
  23. ^ Mörs, Thomas; Reguero, Marcelo; Vasilyan, Davit (2020-04-23). "First fossil frog from Antarctica: implications for Eocene high latitude climate conditions and Gondwanan cosmopolitanism of Australobatrachia". Scientific Reports. 10 (1): 5051. Bibcode:2020NatSR..10.5051M. doi:10.1038/s41598-020-61973-5. ISSN 2045-2322. PMC 7181706. PMID 32327670.
  24. ^ Engelbrecht; Mörs; Reguero; Kriwet, Andrea; Thomas; Marcelo A.; Jürgen (May 2017). "A new saw shark, Pristiophorus laevis, from the Eocene of Antarctica with comments on Pristiophorus lanceolatus". Historical Biology. 29 (6): 841–853. Bibcode:2017HBio...29..841E. doi:10.1080/08912963.2016.1252761. PMC 5447807. PMID 28579693.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  25. ^ Bieńkowska-Wasiluk, M.; Bonde, N.; Møller, P. R.; Gaździcki, A. (2013). "Eocene relatives of cod icefishes (Perciformes: Notothenioidei) from Seymour Island, Antarctica". Geological Quarterly. 57 (4). ISSN 1641-7291.

Further reading

  • R. A. Askin. 1997. Eocene-?Earliest Oligocene terrestrial palynology of Seymour Island, Antarctica. : 993-996. The Antarctic Region: Geological Evolution and Processes 993-996
  • M. A. Bitner. 1991. A supposedly new brachiopod from the Paleogene of Seymour Island, West Antarctica. Polish Polar Research 12(2):243-246
  • D. B. Blake and R. B. Aronson. 1998. Eocene stelleroids (Echinodermata) at Seymour Island, Antarctic Peninsula. Journal of Paleontology 72(2):339-353
  • M. Bond, M. A. Reguero, S. F. Vizcaino and S. A. Marenssi. 2006. A new 'South American ungulate' (Mammalia: Litopterna) from the Eocene of the Antarctic Peninsula. Geological Society, London, Special Publications 258:163-176
  • J. A. Case. 1988. Paleogene floras from Seymour Island, Antarctic Peninsula. Geology and Paleontology of Seymour Island Antarctic Peninsula 523-540
  • M. M. Cenizo. 2012. Review of the putative Phorusrhacidae from the Cretaceous and Paleogene of Antarctica: new records of ratites and pelagornithid birds. Polish Polar Research 33(3):225-244
  • A. L. Cione, M. de las Mercedes Azpelicueta, and D. R. Bellwood. 1995. An oplegnathid fish from the Eocene of Antarctica. Palaeontology 37(4):931-940
  • A. L. Cione and M. A. Reguero. 1994. New records of the sharks Isurus and Hexanchus from the Eocene of Seymour Island, Antarctica. Proceedings of the Geologists' Association 105:1-14
  • J. Kriwet. 2005. Additions to the Eocene Selachian Fauna of Antarctica with Comments on Antarctic Selachian Diversity. Journal of Vertebrate Paleontology 25(1):1-7
  • S. A. Marenssi, M. A. Regeuro, S. N. Santillana and S. F. Vizcaino. 1994. Eocene land mammals from Seymour Island, Antarctica: palaeobiogeographical implications. 6(1):3-15
  • I. Poole, A. M. W. Mennega, and D. J. Cantrill. 2003. Valdivian ecosystems in the Late Cretaceous and Early Tertiary of Antarctica: further evidence from myrtaceous and eucryphiaceous fossil wood. Review of Palaeobotany and Palynology 124:9-27
  • R. R. Pujana, S. N. Santillana, and S. A. Marenssi. 2014. Conifer fossil woods from the La Meseta Formation (Eocene of Western Antarctica): Evidence of Podocarpaceae-dominated forests. Review of Palaeobotany and Palynology (200)122-137
  • S. F. Vizcaino, M. A. Reguero, S. A. Marenssi and S. N. Santillana. 1997. New land mammal-bearing localities from the Eocene La Meseta Formation, Seymour Island, Antarctica. The Antarctic Region: Geological Evolution and Processes 997-1000
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