Earth:Lopez de Bertodano Formation
Lopez de Bertodano Formation Stratigraphic range: Maastrichtian-Danian ~70–65.5 Ma | |
---|---|
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 |
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 |
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]
Cretaceous-Paleogene boundary
The 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
During 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
The 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
- 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
Reptiles 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 | |
Kaikaifilu | K. hervei | Seymour Island. | Several incomplete parts of a skull, jawbone, 30 isolated teeth, and a partial left humerus. | A mosasaur. | |
Morturneria | 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 |
Other fossils
Among 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
- Lists of dinosaur-bearing stratigraphic units
- List of fossiliferous stratigraphic units in Antarctica
- South Polar region of the Cretaceous
References
- ↑ 1.0 1.1 1.2 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. doi:10.1016/j.gr.2015.10.018. Bibcode: 2016GondR..38..132B.
- ↑ 3.0 3.1 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. doi:10.1017/S0022336000024331. https://www.cambridge.org/core/journals/journal-of-paleontology/article/discovery-of-fish-mortality-horizon-at-the-k-t-boundary-on-seymour-island-re-evaluation-of-events-at-the-end-of-the-cretaceous/C6F72A86DAB664F2E2315A34B3875875.
- ↑ 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. doi:10.1130/0091-7613(1994)022<0675:IADATC>2.3.CO;2. Bibcode: 1994Geo....22..675E.
- ↑ 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. doi:10.1038/ncomms12079. PMID 27377632. Bibcode: 2016NatCo...712079P.
- ↑ 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. doi:10.1038/ncomms11738. PMID 27226414. Bibcode: 2016NatCo...711738W.
- ↑ 7.0 7.1 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. doi:10.1130/g35512.1. Bibcode: 2014Geo....42..583K.
- ↑ Vanessa C. Bowman; Jane E. Francis; James B. Riding (2013). "Late Cretaceous winter sea ice in Antarctica?". Geology 41 (12): 1227–1230. doi:10.1130/G34891.1. Bibcode: 2013Geo....41.1227B. http://nora.nerc.ac.uk/id/eprint/504369/1/sea%20ice%20%20revised%20Jim%20edit.pdf.
- ↑ Thomas S. Tobin; Peter D. Ward; Eric J. Steig; Eduardo B. Olivero; Isaac A. Hilburn; Ross N. Mitchell; Matthew R. Diamond; Timothy D. Raub et al. (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. doi:10.1016/j.palaeo.2012.06.029. Bibcode: 2012PPP...350..180T. https://authors.library.caltech.edu/35186/2/mmc1.doc.
- ↑ 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
- ↑ 14.0 14.1 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. doi:10.1371/journal.pone.0114743. PMID 25493546. Bibcode: 2014PLoSO...9k4743C.
- ↑ 16.0 16.1 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". Palaeogeography, Palaeoclimatology, Palaeoecology 418: 193–212. doi:10.1016/j.palaeo.2014.11.002. Bibcode: 2015PPP...418..193W. http://nora.nerc.ac.uk/id/eprint/507013/1/Evolution%20and%20extinction%20of%20Maastrichtian%20%28Late%20Cretaceous%29%20cephalopods%20AAM.pdf.
- ↑ 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. doi:10.1016/j.cretres.2018.01.004. http://sedici.unlp.edu.ar/handle/10915/147537.
- ↑ 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". Nature 433 (7023): 305–308. doi:10.1038/nature03150. PMID 15662422. Bibcode: 2005Natur.433..305C. http://www.digimorph.org/specimens/Vegavis_iaai/nature03150.pdf. 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.
- ↑ 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. 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
Bibliography
- Legendre, Lucas J.; David Rubilar Rogers; Grace M. Musser; Sarah N. Davis; Rodrigo A. Otero; Alexander O. Vargas, and Julia A. Clarke. 2020. A giant soft-shelled egg from the Late Cretaceous of Antarctica. Nature .. .. Accessed 2020-06-17.
Further reading
- 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. doi:10.1016/s0034-6667(02)00244-0.
![]() | Original source: https://en.wikipedia.org/wiki/Lopez de Bertodano Formation.
Read more |