The Lopez de Bertodano Formation is a geological formation in the James Ross archipelago of the Antarctic Peninsula. The strata date from the end of the Late Cretaceous (upper-lower Maastrichtian stage[1]) to the Danian stage of the lower Paleocene, from about 70 to 65.5 million years ago, straddling the Cretaceous-Paleogene boundary.[2]
Lopez de Bertodano Formation | |
---|---|
Stratigraphic range: Maastrichtian-Danian ~ | |
Type | Geological formation |
Unit of | Marambio & Seymour Island Groups |
Sub-units | Cape Lamb & Lower Sandwich Bluff Members |
Underlies | Sobral Fm., La Meseta Fm. |
Overlies | Snow Hill Island Formation |
Lithology | |
Primary | Siltstone, mudstone |
Other | Sandstone with concretions |
Location | |
Coordinates | 64°00′S 57°24′W / 64.0°S 57.4°W |
Approximate paleocoordinates | 61°54′S 68°06′W / 61.9°S 68.1°W |
Region | Seymour Island, James Ross Island group, Vega Island |
Country | Antarctica |
Type section | |
Named for | López de Bertodano Bay |
Cretaceous-Paleogene boundary
editThe Cretaceous–Paleogene boundary (K–Pg) crops out on Seymour Island in the upper levels of the Lopez de Bertodano Formation.[3] A small (but significant) iridium anomaly occurs at the boundary on Seymour Island, as at lower latitudes, thought to be fallout from the Chicxulub impactor in the Gulf of Mexico.[4] Directly above the boundary a layer of disarticulated fish fossils occurs, victims of a disturbed ecosystem immediately following the impact event.[3] Multiple reports have described evidence for climatic changes in Antarctica prior to the mass extinction,[5] but the extent to which these affected marine biodiversity is debated. Based on extensive marine fossil collections from Seymour Island, recent work has confirmed that a single and severe mass extinction event occurred at this time in Antarctica just as at lower latitudes.[6]
Climate
editDuring the Maastrichtian, Seymour Island was located within the Antarctic polar circle at around ~65°S latitude.[7] Chemical studies on oxygen-18 isotopes found in shells and benthic foraminifera have calculated intermediate-depth and deep-sea ocean temperatures at a mean average of 6 °C (43 °F) with fluctuations of 4–12 °C (39–54 °F) throughout the Maastrichtian; one of the same studies has also suggested that sea surface temperatures may have been colder, possibly dropping below freezing and forming sea ice at times.[8][9] Alternatively, a study using data acquired from ancient bacterial membrane lipids yielded a slightly warmer temperature of 12 ± 5 °C (54 ± 9 °F) around 66 Ma. Nevertheless, these estimated climates characterize primarily cool temperate environments with possible subpolar and warm episodes.[7]
Fossil content
editThe Lopez de Bertodano Formation has provided many fossils of flora, dinosaurs and birds.[10][11][12] Also the first fossil egg from Antarctica, Antarcticoolithus, was found in the formation.[13]
Dinosaur remains are among the fossils that have been recovered from the formation[14] and include at least two and probably as much as six lineages of indisputably modern birds: one related to waterfowl, a primitive shorebird or related form, 1 to 2 species of possible loons, a large and possibly flightless bird belonging to a lineage extinct today as well as a partial skull that might belong to either of the smaller species or represent yet another one. The formation also contains a rich fossil invertebrate fauna, including bivalves, gastropods,[15] and cephalopods (ammonites and nautiloids).[16]
The fish assemblage of the López de Bertodano Formation was dominated by Enchodus and ichthyodectiformes, accounting for 21.95% and 45.6% of local fish diversity respectively. Of the remaining percentages, sand sharks made up 10.5%, the cow shark Notidanodon 6.8%, chimaeras 3.9%, saw sharks 2.7%, various other teleost fish 2.4%, and the remaining 6% were shared between other sharks like Paraorthacodus, frilled sharks, Protosqualus, and Cretalamna.[17]
Dinosaurs
editColor key
|
Notes Uncertain or tentative taxa are in small text; |
- Theropod
Theropods recorded from Lopez de Bertodano Formation | |||||
---|---|---|---|---|---|
Genus | Species | Member | Material | Description | Image |
Charadriiform[18] | Unnamed species | Cape Lamb | Partial skeleton | ||
Conflicto | C. antarcticus | Partial skeleton | An anseriform | ||
Neornithes | Indeterminate. | Partial skull | Relationships undetermined, cranium some 5–6 centimetres (2.0–2.4 in) long | ||
Polarornis | P. gregorii | Lower Sandwich Bluff | Partial skull and skeleton, holotype | A loon?[14] | |
P.? sp. | Lower Sandwich Bluff | Partial skeleton including wing and hindlimbs | Possibly a more primitive form with strong flight ability and lighter bones | ||
Vegavis | V. iaai[19] | Lower Sandwich Bluff | Partial skeleton, holotype | An anseriform | |
V. sp. | Cape Lamb | Isolated femur | Initially identified as a fossil of a member of Cariamae,[20] but subsequently reinterpreted as a fossil of an unnamed large-bodied member of the genus Vegavis.[21] | ||
Theropoda | Indeterminate. | Fragments[1] |
- Ornithopods
Ornithopods recorded from Lopez de Bertodano Formation | |||||
---|---|---|---|---|---|
Genus | Species | Member | Material | Description | Image |
Hadrosauridae | Indeterminate. | Sandwich Bluff Member | Isolated cheek tooth, MLP 98-I-10-1.[1] |
Reptiles
edit- Elasmosaurs
Elasmosaurs recorded from Lopez de Bertodano Formation | |||||
---|---|---|---|---|---|
Genus | Species | Member | Material | Description | Image |
Aristonectes[22] | A. parvidens | Seymour Island | Partial postcranial skeleton (MLP 89-III-3-1) | A giant elasmosaur | |
Marambionectes[23] | M. molinai | Seymour Island | Partially articulated incomplete skeleton including cranial material, many vertebrae, ribs, an ilium, limb bones (right humerus and ulna, a femur), and gastroliths (IAA-Pv 752) | A weddellonectian elasmosaur |
|
Morturneria[24] | M. seymourensis | Seymour Island | several cervical vertebrae, a right humerus, a nearly complete left forelimb missing the proximal end of the humerus, and a left femur (TTU P9217) | An elasmosaur |
- Mosasaurs
Mosasaurs recorded from Lopez de Bertodano Formation | |||||
---|---|---|---|---|---|
Genus | Species | Member | Material | Description | Image |
Antarcticoolithus | A. bradyi | Seymour Island. | A fossilized eggshell. | A mosasaur. | |
Kaikaifilu[25] | K. hervei | Seymour Island | Several incomplete parts of a skull, jawbone, 30 isolated teeth, and a partial left humerus (SGO.PV.6509) | A tylosaurine mosasaur |
Other fossils
editAmong others, the following fossils have been found in the formation:
- Ammonites[16]
Ammonites recorded from Lopez de Bertodano Formation | |||||
---|---|---|---|---|---|
Genus | Species | Member | Material | Description | Image |
Diplomoceras | D. cylindraceum | A paperclip-shaped Ammonite. | |||
Gaudryceras | G. seymouriense | ||||
Grossouvrites | G. joharae | ||||
Kitchinites | K. laurae | ||||
Maorites | M. densicostatus | ||||
Pachydiscus | P. (Pachydiscus) ultimus | ||||
Pseudophyllites | P. cf. loryi | ||||
Zelandites | Z. varuna |
- Other invertebrates
Invertebrates recorded from Lopez de Bertodano Formation | |||||
---|---|---|---|---|---|
Genus | Species | Member | Material | Description | Image |
Eutrephoceras | E. dorbignyanum | ||||
Cyathocidaris | C. nordenskjoldi | ||||
C. patera | |||||
Rotularia | R. fallax |
- Flora
- Antarctoxylon juglandoides
- Eucryphiaceoxylon eucryphioides
- Myrceugenelloxylon antarcticus
See also
editReferences
edit- ^ a b c Olivero, E.B.; Ponce, J.J.; Marsicano, C.A.; Martinioni, D.R. (2007). "Depositional settings of the basal Lopez de Bertodano Formation, Maastrichtian, Antarctica". Revista de la Asociación Geológica Argentina. 62 (4): 521–529.
- ^ Bowman, V.; Ineson, J.; Riding, J.; Crame, J.; Francis, J.; Condon, D.; Whittle, R.; Ferraccioli, F. (2016). "The Paleocene of Antarctica: Dinoflagellate cyst biostratigraphy, chronostratigraphy and implications for the palaeo-Pacific margin of Gondwana". Gondwana Research. 38: 132–148. Bibcode:2016GondR..38..132B. doi:10.1016/j.gr.2015.10.018.
- ^ a b Zinsmeister, W.J. (1998). "Discovery of fish mortality horizon at the K-T Boundary on Seymour Island: Re-evaluation of events at the end of the Cretaceous". Journal of Paleontology. 72 (3): 556–571. Bibcode:1998JPal...72..556Z. doi:10.1017/S0022336000024331. S2CID 132206016.
- ^ Elliot D.H.; Askin RA; Kyte FT; Zinsmeister WJ (1994). "Iridium and dinocysts at the Cretaceous-Tertiary boundary on Seymour Island, Antarctica: Implications for the K-T event". Geology. 22 (8): 675. Bibcode:1994Geo....22..675E. doi:10.1130/0091-7613(1994)022<0675:IADATC>2.3.CO;2.
- ^ Petersen, S.V.; Dutton A; Lohmann KC (2016). "End-Cretaceous extinction in Antarctica linked to both Deccan volcanism and meteorite impact via climate change". Nature Communications. 7: 12079. Bibcode:2016NatCo...712079P. doi:10.1038/ncomms12079. PMC 4935969. PMID 27377632.
- ^ Witts J.D.; Whittle RJ; Wignall PB; Crame JA; Francis JE; Newton RJ; Bowman VC (2016). "Macrofossil evidence for a rapid and severe Cretaceous-Paleogene mass extinction in Antarctica". Nature Communications. 7: 11738. Bibcode:2016NatCo...711738W. doi:10.1038/ncomms11738. PMC 4894978. PMID 27226414.
- ^ a b David B. Kemp; Stuart A. Robinson; J. Alistair Crame; Jane E. Francis; Jon Ineson; Rowan J. Whittle; Vanessa Bowman; Charlotte O'Brien (2014). "A cool temperate climate on the Antarctic Peninsula through the latest Cretaceous to early Paleogene". Geology. 42 (7): 583–586. Bibcode:2014Geo....42..583K. doi:10.1130/g35512.1. hdl:2164/4380.
- ^ Vanessa C. Bowman; Jane E. Francis; James B. Riding (2013). "Late Cretaceous winter sea ice in Antarctica?" (PDF). Geology. 41 (12): 1227–1230. Bibcode:2013Geo....41.1227B. doi:10.1130/G34891.1. S2CID 128885087.
- ^ Thomas S. Tobin; Peter D. Ward; Eric J. Steig; Eduardo B. Olivero; Isaac A. Hilburn; Ross N. Mitchell; Matthew R. Diamond; Timothy D. Raub; Joseph L. Kirschvink (2012). "Extinction patterns, δ18 O trends, and magnetostratigraphy from a southern high-latitude Cretaceous–Paleogene section: Links with Deccan volcanism". Palaeogeography, Palaeoclimatology, Palaeoecology. 350–352 (2012): 180–188. Bibcode:2012PPP...350..180T. doi:10.1016/j.palaeo.2012.06.029.
- ^ Marambio Group - Lopez de Bertodano Formation at Fossilworks.org
- ^ Seymour Island Group - Lopez de Bertodano Formation at Fossilworks.org
- ^ Upper Lopez de Bertodano Formation at Fossilworks.org
- ^ Legendre et al., 2020
- ^ a b Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Cretaceous, Antarctica)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. p. 606. ISBN 0-520-24209-2.
- ^ Crame, J.A.; Beu, A.G.; Ineson J.R.; Francis J.A.; Whittle R.J.; Bowman V.C. (2014). "The Early Origin of the Antarctic Marine Fauna and Its Evolutionary Implications". PLOS ONE. 7 (12): e114743. Bibcode:2014PLoSO...9k4743C. doi:10.1371/journal.pone.0114743. PMC 4262473. PMID 25493546.
- ^ a b Witts, J.D.; Bowman V.C.; Wignall P.B.; Crame J.A.; Francis, J.E.; Newont, R.J. (2015). "Evolution and extinction of Maastrichtian (Late Cretaceous) cephalopods from the López de Bertodano Formation, Seymour Island, Antarctica" (PDF). Palaeogeography, Palaeoclimatology, Palaeoecology. 418: 193–212. Bibcode:2015PPP...418..193W. doi:10.1016/j.palaeo.2014.11.002.
- ^ Alberto L. Cione; Sergio Santillana; Soledad Gouiric-Cavalli; Carolina Acosta Hospitaleche; Javier N. Gelfo; Guillermo M. Lopez; Marcelo Reguero (2018). "Before and after the K/Pg extinction in West Antarctica: New marine fish records from Marambio (Seymour) Island". Cretaceous Research. 85: 250–265. Bibcode:2018CrRes..85..250C. doi:10.1016/j.cretres.2018.01.004. hdl:11336/99687.
- ^ Cordes (2002). "A new charadriiform avian specimen from the Early Maastrichtian of Cape Lamb, Vega Island, Antarctic Peninsula". Journal of Vertebrate Paleontology. 22 (3): 46A.
- ^ Clarke, J.A.; Tambussi, C.P.; Noriega, J.I.; Erickson, G.M.; Ketcham, R.A. (2005). "Definitive fossil evidence for the extant avian radiation in the Cretaceous" (PDF). Nature. 433 (7023): 305–308. Bibcode:2005Natur.433..305C. doi:10.1038/nature03150. PMID 15662422. S2CID 4354309. Supporting information
- ^ Case, J.; Reguero, M.; Martin, J.; Cordes-Person, A. (2006). "A cursorial bird from the Maastrictian of Antarctica". Journal of Vertebrate Paleontology. 26 (3): 48A. doi:10.1080/02724634.2006.10010069. S2CID 220413406.
- ^ Abagael R. West; Christopher R. Torres; Judd A. Case; Julia A. Clarke; Patrick M. O'Connor; Matthew C. Lamanna (2019). "An avian femur from the Late Cretaceous of Vega Island, Antarctic Peninsula: removing the record of cursorial landbirds from the Mesozoic of Antarctica". PeerJ. 7: e7231. doi:10.7717/peerj.7231. PMC 6626523. PMID 31333904.
- ^ O'Gorman, J. P., Gasparini, Z., & Salgado, L. (2012). Postcranial morphology of Aristonectes (Plesiosauria, Elasmosauridae) from the Upper Cretaceous of Patagonia and Antarctica. Antarctic Science, 25(1), 71–82. https://doi.org/10.1017/S0954102012000673
- ^ O'Gorman, Jose P.; Canale, Juan I.; Bona, Paula; Tineo, David E.; Reguero, Marcelo; Cárdenas, Magalí (2024-12-31). "A new elasmosaurid (Plesiosauria: Sauropterygia) from the López de Bertodano Formation: new data on the evolution of the aristonectine morphology". Journal of Systematic Palaeontology. 22 (1). Bibcode:2024JSPal..2212302O. doi:10.1080/14772019.2024.2312302. ISSN 1477-2019.
- ^ Chatterjee, S.; Small, B. J. (1989). "New plesiosaurs from the Upper Cretaceous of Antarctica". Geological Society Special Publications. 47 (1): 197–215. Bibcode:1989GSLSP..47..197C. doi:10.1144/GSL.SP.1989.047.01.15. S2CID 140639013.
- ^ Rodrigo A. Otero; Sergio Soto-Acuña; David Rubilar-Rogers; Carolina S. Gutstein (2017). "Kaikaifilu hervei gen. et sp. nov., a new large mosasaur (Squamata, Mosasauridae) from the upper Maastrichtian of Antarctica". Cretaceous Research. 70: 209–225. Bibcode:2017CrRes..70..209O. doi:10.1016/j.cretres.2016.11.002. S2CID 133320233.
Bibliography
edit- Legendre, Lucas J.; Rubilar Rogers, David; Musser, Grace M.; Davis, Sarah N.; Otero, Rodrigo A.; Vargas, Alexander O.; Clarke, Julia A. (2020), "A giant soft-shelled egg from the Late Cretaceous of Antarctica", Nature, 583 (7816): 411–414, Bibcode:2020Natur.583..411L, doi:10.1038/s41586-020-2377-7, PMID 32555453, retrieved 2020-06-17
Further reading
edit- Poole, I.; Mennega, A. M. W.; Cantrill, D. J. (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 (1–2): 9–27. Bibcode:2003RPaPa.124....9P. doi:10.1016/s0034-6667(02)00244-0. hdl:1874/31608. S2CID 129281012.