Cryolophosaurus(/ˌkrəˌlfəˈsɔːrəs/or/krˌɒləfəˈsɔːrəs/;KRY-ə-LOH-fə-SAWR-əs) is agenusof largetheropoddinosaur known from only a singlespeciesCryolophosaurus ellioti,from the earlyJurassicofAntarctica.It was one of the largest theropods of the Early Jurassic, with the subadult being estimated to have reached 6–7 metres (20–23 ft) long and weighed 350–465 kilograms (772–1,025 lb).

Cryolophosaurus
Temporal range:Early Jurassic(Pliensbachian),186–182Ma
[1]
Reconstructed holotype skeleton
Reconstructed skeleton,Field Museum of Natural History
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Neotheropoda
Genus: Cryolophosaurus
Hammer&Hickerson,1994
Type species
Cryolophosaurus ellioti
Hammer & Hickerson, 1994

Cryolophosauruswas first excavated from Antarctica's Early Jurassic,PliensbachianagedHanson Formation,formerly the upper Falla Formation, bypaleontologistDr. William Hammerin 1991. It was the firstcarnivorousdinosaur to be discovered in Antarctica and the first non-avian dinosaur from the continent to be officially named. The sediments in which its fossils were found have been dated at ~196 to 188 million years ago, representing the Early JurassicPeriod.

Cryolophosaurusis known from a skull, a femur and other material, all of which have caused its classification to vary greatly. The femur possesses many primitive characteristics that have classifiedCryolophosaurusas adilophosauridor a neotheropod outside of Dilophosauridae and Averostra, whereas the skull has many advanced features, leading the genus to be considered a tetanuran, an abelisaurid, a ceratosaur and even an allosaurid.[2][3]Cryolophosaurusis currently considered to be a derivedneotheropod,close toAverostra.Additionally,Cryolophosauruspossessed a distinctive "pompadour"crest that spanned the head from side to side. Based on evidence from related species and studies of bone texture, it is thought that this bizarre crest was used forintra-species recognition.ThebrainofCryolophosauruswas also more primitive than those of other theropods.

Discovery and naming

edit
Map showing location of theMount Kirkpatrickdinosaur site, withstratigraphiccontext on the right

Cryolophosaurusoriginally was collected during the 1990–91 austral summer onMount Kirkpatrickin theBeardmore Glacierregion of theTransantarctic Mountains.The discovery was made by Hammer, a professor atAugustana College,and his team. The fossils were found in thesiliceoussiltstoneof theHanson Formation,formerly the upper Falla Formation, and dated to thePliensbachian Stageof the earlyJurassic.Cryolophosauruswas the second dinosaur, and first theropod, to be discovered in Antarctica. It was discovered afterAntarctopelta,but named earlier.[4]

In 1991, both Hammer and theOhio State UniversitygeologistDavid Elliotexcavated separate outcrops near Beardmore Glacier, sharing logistical expenses. Elliot's team first came across the remains ofCryolophosaurusin a rock formation around the altitude of 4,000 m (13,000 ft) high and about 640 km (400 mi) from the South Pole. When the discovery was made, they soon notified Hammer. Over the next three weeks, Hammer excavated 2,300 kg (5,100 lb) of fossil-bearing rock. The team recovered over 100 fossil bones, including those ofCryolophosaurus.[4]The specimens were formally named and described in 1994 by Hammer and Hickerson, in the journalScience.[4]

During the 2003 season, a field team returned and collected more material from the original site. A second locality was discovered about 30 metres (98 ft) higher in the section on Mt. Kirkpatrick.[5]

The nameCryolophosaurus elliotiis derived from theGreekwords κρυος (meaning 'cold' or 'frozen', in reference to its discovery in Antarctica), λοφος (meaning 'crest') andσαυρος(meaning 'lizard'), thus "cold crest lizard". Hammer and Hickerson named the speciesC. ellioti,after David Elliot, who had made the initial discovery of the fossils.[4]

Description

edit
Size comparison

Cryolophosauruswas a large, well-builttheropod,one of the largest of its time. The holotype specimen is estimated to have reached 6–7 m (20–23 ft) long and weighed 350–465 kg (772–1,025 lb).[6][7][8]In 2016 Molina-Pérez and Larramendi gave a larger estimation of 7.7 meters (25.3 ft) and 780 kg (1,720 lb).[9]Some researchers noted that the holotype individual probably represents a sub-adult, so adults could have been larger.[7][10]Despite having slender proportions,Cryolophosaurusis one of the largest knownEarly Jurassictheropods.[10][11]

TheholotypeFMNH PR1821 is the only fully described specimen ofCryolophosaurus.The specimen consists of an incompleteskullandmandibleslacking most of their front half; nine maxillaryteeth;a fragmentary sixth cervical centrum; cervicalvertebrae7–10; several posterior cervicalribs;several anterior dorsal vertebrae; most mid and posterior dorsal vertebrae; several dorsal ribs; the fifth sacral vertebrae; threechevrons;many partial and complete caudal vertebrae and centra; two partialhumeri;a proximalradius;a proximalulna;a partialilium;a proximalpubis;bothischia,but only onedistal;two incompletefemora;the distal end of atibia;the distal end of afibula,and the astragalus and calcaneum.[7]In 2013, new material ofCryolophosauruswas unearthed in Antarctica. The description of this material has not yet been published in a non-abstract form.[12]

Skull

edit
Life restoration

The holotype ofCryolophosaurusconsists of a high, narrow skull, which was discovered articulated with the rest of the skeleton.[6]The skull is an estimated 65 centimetres (26 in) long. It has a peculiar nasal crest that runs just over the eyes, where it rises perpendicular to the skull and fans out. It is thin and highly furrowed, giving it a unique"pompadour"appearance and earned it the nickname "Elvisaurus. "[13]The crest is an extension of the skull bones, near the tear ducts, fused on either side to orbital horns which rise from the eye sockets. While other theropods like theMonolophosaurushave crests, they usually run along the skull instead of across it.[14]

An unpublished study conducted by Vernon Meidlinger-Chin in 2013 suggested that previous studies lacked focus on endocranial details. The study found that theCryolophosaurusfossil has a nearly complete, undistorted cranial cavity which is complete enough to give an approximate shape and size of the living brain. The endocast features clarified the dissimilarity of the skull with those ofAllosauroidsandCoelurosaursgivingCryolophosaurusabasalposition in Theropoda.[11]Closer examination of how the skull bones fused reviewed details in the snout and forehead that are exceptionally similar toDilophosaurus.[15]

Classification

edit
The unrestoredholotypeskull,FMNHPR1821.
Fossil pelvis ofCryolophosaurus.The loop at the widest part of the pubis is large compared to later theropods.

ClassificationofCryolophosaurusis difficult because it has a mix of primitive and advanced characteristics.[16]The femur has traits of early theropods, while the skull resembles much later species of thecladeTetanurae,like China'sSinraptorandYangchuanosaurus.This ledPaul Serenoet al.(1994) to placeCryolophosaurusin the taxon Allosauridae.[17]Originally, Hammer and colleagues suspected thatCryolophosaurusmight be aceratosauror even an earlyabelisaur,with some traitsconvergentwith those of more advanced tetanurans, but ultimately concluded that it was itself the earliest known member of the tetanuran group.[4]While a subsequent study by Hammer (along with Smith and Currie) again recoveredCryolophosaurusas a tetanuran, a later (2007) study by the same authors found that it was more closely related toDilophosaurusandDracovenator.[14][18]Sterling Nesbittet al.(2009), using the characters ofTawafoundCryolophosaurusto be neither a dilophosaurid nor averostran neotheropod but instead the sister group of a clade composed ofdilophosauridsandaverostrans.[19]However, in 2012, Matthew Carrano found thatCryolophosauruswas a tetanuran, related toSinosaurus,but unrelated toDilophosaurus.[20]In 2020, a monograph ofDilophosaurusfoundCryolophosaurusto be a derived neotheropod, close to Averostra, in a more derived position thanZupaysaurus,but less thanDilophosaurus.[21]

The following cladogram illustrates a synthesis of the relationships of the early theropod groups compiled by Hendrickxet al.in 2015.[22]

Neotheropoda
Restoration of aCryolophosaurusin its environment

However, a 2020 study conducted by Adam Marsh and Timothy Rowe found Cryolophosaurus to be a basal Neotheropod. While it was still closer to Averostra than Coelophysoidea was, it was still more basal than Dilophosaurus.[23]

Paleobiology

edit

Cranial ornamentation

edit
Reconstructed skull

Cranial display features, such as the one possessed byCryolophosaurus,make sense in social, gregarious animals, where other members of the species are available to observe and interpret messages of sexual status.[24]Kevin Padianet al.(2004) challenged conventional hypotheses that the purpose of bizarre cranial structures and post-cranial armor in dinosaurs, was either for attracting mates, intimidating/fighting rivals in the group, or intimidating potential predators of other species. Padianet al.noted that based on phylogenetic, histological, and functional evidence these bizarre structures can be explained by the phenomenon ofintra-species recognition,which is supported by the fossil evidence.[25][26]Thomas R. Holtz Jr.(2010) found that the bizarre crest ofCryolophosauruswas primarily for intra-species recognition, based on evidence from related species and studies of bone texture.[27]According to Thomas Rich and his colleagues, the crest would have been ineffective as a weapon and may have possibly functioned as a display feature during certain types of social behavior such as mating.[28]In 2019, a species recognition function was disputed but a socio-sexual display structure model was suggested.[29]

Diet

edit
Cryolophosaurus caudal vertebrae dorsal view

When the type specimen was discovered, several long cervical ribs, of a supposed prosauropod dinosaur were found in the mouth ofCryolophosaurus,which led Hammer (1998) to conclude that it was feeding on the prosauropod when it died. Hammer further noted that since the ribs were found extending all the way back to the theropod's neck region, this individual may have choked to death on these ribs.[6]However, Smithet al.concluded that these remains belonged to theCryolophosaurusspecimen itself, and not to Hammer's "prosauropod".[18]Hammer also concluded that a post-canine tooth belonging to atritylodont(an early mammal relative), found with the remains, was part of its stomach contents when it died.[30]

Paleopathology

edit
Cryolophosaurusleft tibia (upper) and left tibia and fibula (lower) with calcaneum and astragalus

SomeCryolophosaurusbones have pathologies that show evidence of scavenging. Broken teeth from a juvenileCryolophosauruswere found nearby.[28]These teeth have no roots and likely shed naturally while scavenging the adultCryolophosauruscarcass.

Another possible pathology is found in theastragalus(ankle bone) ofCryolophosaurus.This bone was preserved with a small splint from thefibulalocated just above the ankle. The splint, however, may also be just a unique morphological feature ofCryolophosaurus.[7]

Paleoenvironment

edit
Some sediments in theHanson Formationare of volcanic origin, suggestingPlinian eruptionsduring the deposition

All known specimens ofCryolophosaurushave been recovered in the Hanson Formation, which is one of only two major dinosaur-bearing rock formations found on the continent of Antarctica.Cryolophosauruswas found about 650 kilometres (400 mi) from theSouth Polebut,[6]at the time it lived, this was about 1,000 km (621 mi) or so farther north.[31]The Hanson Formation accumulated in a rift environment located between c. 60 and 70S, fringing theEast Antarctic Cratonbehind the activePanthalassanmargin of southern Gondwana, being dominated by two types of facies: "tuffaceous" siltstone of fluvial and volcanic strata, deposited maybe more than 10 million years based on the thickness.[32]In the Early Jurassic, Antarctica was closer to theequatorand the world was considerably warmer than today, but theclimatewas still cooltemperatesimilar to that of modern southernChile,and humid, with a temperature interval of 17–18 degrees. Models of Jurassic air flow indicate that coastal areas probably never dropped much below freezing, although more extreme conditions existed inland.[33]

This formation has produced the remains of two smaller theropods, the sauropodomorphGlacialisaurus,[34]a crow-sizedpterosaur(adimorphodontid), atritylodont,herbivorous synapsid, and two small unnamed sauropodomorphs.[35][36]Beyond vertebrates, Insects (Blattodea,Coleoptera),Ostracodans,Conchostracansand arthropod ichnofossils (Diplichnites,Planolites,Scoyenia) are know from other coeval localities, likeGair Mesa,Mount CarsonorShafer Peak.[37]Plant remains are also very common, from large tree trunks (+50 cm) at Mount Carson to Palynomorphs at Shafer Peak.[38]Macrofoliar and cuticle remains have also been recovered from several localities, including Conifers (Araucariaceae,Cheirolepidiaceae,Cupressaceae,PinaceaeorVoltziales), Cycadophytes (Bennettitales), Pteridosperms (Corystospermaceae), Ferns (Dipteridaceae,Matoniaceae,OsmundaceaeandPolypodiales),Equisetaceae,IsoetaceaeandLiverworts(Marchantiales).[39]Some of the plant remains are relictual genera, like the youngest record ofDicroidium.[40]Common presence of the invertebrate ichnogenusPlanolitesindicates the local fluvial, alluvial or lacustrine waters where likely continuous all year, as well the presence of abundantOtozamitestrends to suggest high humidity.[39]Overall points to a setting with strong seasonality in day-length given the high latitude, perhaps similar to warm-temperate, frost-free forest and open woodland as in North Island ofNew Zealand.Despite the proper conditions, peat accumulation was rare, mostly due to the influence of local volcanism, with common wildfire activity as shown by charred coalified plant remains.[39]

References

edit
  1. ^Bomfleur, B.; Schöner, R.; Schneider, J. W.; Viereck, L.; Kerp, H.; McKellar, J. L. (2014)."From the Transantarctic Basin to the Ferrar Large Igneous Province—new palynostratigraphic age constraints for Triassic–Jurassic sedimentation and magmatism in East Antarctica".Review of Palaeobotany and Palynology.207(1): 18–37.Bibcode:2014RPaPa.207...18B.doi:10.1016/j.revpalbo.2014.04.002.Retrieved20 February2022.
  2. ^Evans, D.C.; Vavrek, M.J. (2012).Ultimate Dinosaurs: Giants from Gondwana.Toronto:Royal Ontario Museum. pp. 30–1.
  3. ^Pickrell, John (2004)."Two New Dinosaurs Discovered in Antarctica".National Geographic.Archived fromthe originalon March 11, 2004.Retrieved20 December2013.
  4. ^abcdeHammer, W. R.; Hickerson, W. J. (1994). "A Crested Theropod Dinosaur from Antarctica".Science.264(5160): 828–830.Bibcode:1994Sci...264..828H.doi:10.1126/science.264.5160.828.PMID17794724.S2CID38933265.
  5. ^Leslie, M (2007)."The Strange Lives of Polar Dinosaurs".Smithsonian Magazine.Archived fromthe originalon 2012-07-02.Retrieved2008-01-24.
  6. ^abcdHammer, W.R.; Hickerson, W.J. (1999). Tomida, Y.; Rich, T.H.; Vickers-Rich, Y. (eds.). "Gondwana Dinosaurs from the Jurassic of Antarctica".Proceedings of the Second Gondwana Dinosaur Symposium National Science Museum Monographs.15: 211–217.
  7. ^abcdSmith, N.D.; Makovicky, P.J.; Hammer, W.R.; Currie, P.J. (2007)."Osteology ofCryolophosaurus ellioti(Dinosauria: Theropoda) from the Early Jurassic of Antarctica and implications for early theropod evolution "(PDF).Zoological Journal of the Linnean Society.151(2): 377–421.doi:10.1111/j.1096-3642.2007.00325.x.[permanent dead link]
  8. ^Paul, Gregory S. (2010). "Theropods".The Princeton Field Guide to Dinosaurs.Princeton: Princeton University Press. pp. 67–162.doi:10.1515/9781400836154.67b.ISBN9781400836154.
  9. ^Molina-Pérez & Larramendi (2016).Récords y curiosidades de los dinosaurios Terópodos y otros dinosauromorfos.Barcelona, Spain: Larousse. p. 254.
  10. ^abBenson, R.; Brusatte, S.; Hone, D.; Naish, D.; Xu, X.; Anderson, J.; Clack, J.; Duffin, C.; Milner, A.; Parsons, K.; Prothero, D.; Johanson, Z.; Dennis-Bryan, K. (2012) [2009]. Ambrose, Jamie; Gilpin, David; Hirani, Salima; Jackson, Tom; Joyce, Nathan; Maiklem, Lara; Marriott, Emma; Nottage, Claire; van Zyl, Meizan (eds.).Prehistoric Life: A Definitive Visual History of Life on Earth.Dorling Kindersley.pp. 1–512.ISBN978-0-7566-9910-9.OCLC444710202.
  11. ^abMeidlinger-Chin, V. (2013)."Braincase and Endocranial anatomy ofCryolophosaurus ellioti(Dinosauria: Theropoda) from the Early Jurassic of Antarctica ".Geological Society of America Abstracts with Programs.45(4): 65.
  12. ^Smith, N.D.; Hammer, W.R.; Makovicky, P.J. (2013)."New Dinosaurs from the Early Jurassic Hanson Formation of Antarctica, and Patterns of Diversity and Biogeography in Early Jurassic Sauropodomorphs".Geological Society of America Abstracts with Programs:405–406. Archived fromthe originalon 2017-12-22.Retrieved2013-12-20.
  13. ^swigodner (2017-08-02)."Antarctic Dinosaurs".Field Museum.Retrieved2018-12-31.
  14. ^abSmith, N. D.; Hammer, W.R.; Currie, P.J. (2005). "Osteology and phylogenetic relationships ofCryolophosaurus ellioti(Dinosauria: Theropoda): Implications for basal theropod evolution ".Journal of Vertebrate Paleontology.25(3): 116A–117A.doi:10.1080/02724634.2005.10009942.S2CID220413556.
  15. ^"VERTEBRAL ANATOMY OF CRYOLOPHOSAURUS ELLIOTI, A THEROPOD DINOSAUR FROM THE EARLY JURASSIC OF ANTARCTICA".gsa.confex.com.Archived fromthe originalon 2019-01-01.Retrieved2018-12-31.
  16. ^Holtz, T.R. Jr.; Molnar, R.E.; Currie, P.J. (2004). "Basal Tetanurae". In Weishampel, D.B.; Dodson, P.; Osmólska, H. (eds.).The Dinosauria (Second ed.).University of California Press. pp. 71–110.ISBN978-0-520-24209-8.
  17. ^Sereno, P.C.; Wilson, J.A.; Larsson, H.C.E.; Dutheil, D.B.; Sues, H-D. (1994). "Early Cretaceous dinosaurs from the Sahara".Science.266(5183): 267–270.Bibcode:1994Sci...266..267S.doi:10.1126/science.266.5183.267.PMID17771449.S2CID36090994.
  18. ^abSmith, N. D.; Makovicky, P.J.; Pol, D.; Hammer, W.R.; Currie, P.J. (2007). "The Dinosaurs of the Early Jurassic Hanson Formation of the Central Transantarctic Mountains: Phylogenetic Review and Synthesis".US Geological Survey Open-File Report.2007(1047srp003).doi:10.3133/of2007-1047.srp003.
  19. ^Nesbitt, S.J.; Smith, N.D.; Irmis, R.B.; Turner, A.H.; Downs, A.; Norell, M.A. (2009). "A complete skeleton of a Late Triassic saurischian and the early evolution of dinosaurs".Science.326(5959): 1530–1533.Bibcode:2009Sci...326.1530N.doi:10.1126/science.1180350.PMID20007898.S2CID8349110.
  20. ^Carrano, M. T.; Benson, R. B. J.; Sampson, S. D. (2012). "The phylogeny of Tetanurae (Dinosauria: Theropoda)".Journal of Systematic Palaeontology.10(2): 211–300.doi:10.1080/14772019.2011.630927.S2CID85354215.
  21. ^Marsh, Adam D.; Rowe, Timothy B. (July 2020)."A comprehensive anatomical and phylogenetic evaluation of Dilophosaurus wetherilli (Dinosauria, Theropoda) with descriptions of new specimens from the Kayenta Formation of northern Arizona".Journal of Paleontology.94(S78): 1–103.Bibcode:2020JPal...94S...1M.doi:10.1017/jpa.2020.14.ISSN0022-3360.S2CID220601744.
  22. ^Hendrickx, C.; Hartman, S.A.; Mateus, O. (2015). "An Overview of Non- Avian Theropod Discoveries and Classification".PalArch's Journal of Vertebrate Palaeontology.12(1): 1–73.
  23. ^Marsh, Adam D.; Rowe, Timothy B. (July 2020)."A comprehensive anatomical and phylogenetic evaluation of Dilophosaurus wetherilli (Dinosauria, Theropoda) with descriptions of new specimens from the Kayenta Formation of northern Arizona".Journal of Paleontology.94(S78): 1–103.Bibcode:2020JPal...94S...1M.doi:10.1017/jpa.2020.14.ISSN0022-3360.S2CID220601744.
  24. ^Dodson, P. (1997). "Paleoecology". In Currie, P.J.; Padian, K. (eds.).Encyclopedia of Dinosaurs.Academic Press.ISBN978-0-12-226810-6.
  25. ^Glut, D.F. (2006).Dinosaurs, the Encyclopedia, Supplement 4.McFarland & Company, Inc. p. 749.ISBN978-0-7864-2295-1.
  26. ^Padian, K.; Horner, J.R.; Dhaliwal, J. (2004). "Species recognition as the principal cause of bizarre structures in dinosaurs".Journal of Vertebrate Paleontology.23(3 Suppl): 100A.doi:10.1080/02724634.2003.10010538.S2CID220410105.
  27. ^Holtz, T.R. Jr. (2012).Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages.Random House Books for Young Readers. pp.90–91.ISBN978-0-375-82419-7.
  28. ^abRich, T.R.; Gangloff, R.A.; Hammer, W.R. (1997). "Polar dinosaurs". In Currie, P.J.; Padian, K. (eds.).Encyclopedia of Dinosaurs.Academic Press. pp. 562–573.ISBN978-0-12-226810-6.
  29. ^Chan-gyu, Yun. (2019). "An enigmatic theropod Cryolophosaurus: Reviews and Comments on its paleobiology".Volumina Jurassica.17:1–8.
  30. ^Glut, D.F. (1999).Dinosaurs, the Encyclopedia, Supplement 1.McFarland & Company, Inc. p. 442.ISBN978-0-7864-0591-6.
  31. ^Dodson, P. (1997). "Distribution and Diversity". In Currie, P.J.; Padian, K. (eds.).Encyclopedia of Dinosaurs.Academic Press. pp. 10–13.ISBN978-0-12-226810-6.
  32. ^Elliot, D. H.; Larsen, D.; Fanning, C. M.; Fleming, T. H.; Vervoort, J. D. (2017)."The Lower Jurassic Hanson Formation of the Transantarctic Mountains: implications for the Antarctic sector of the Gondwana plate margin"(PDF).Geological Magazine.154(4): 777–803.Bibcode:2017GeoM..154..777E.doi:10.1017/S0016756816000388.S2CID132900754.Retrieved7 March2022.
  33. ^Chandler, M. A.; Rind, D.; Ruedy, R. (1992)."Pangaean climate during the Early Jurassic: GCM simulations and the sedimentary record of paleoclimate".Geological Society of America Bulletin.104(1): 543–559.Bibcode:1992GSAB..104..543C.doi:10.1130/0016-7606(1992)104<0543:PCDTEJ>2.3.CO;2.
  34. ^Smith, Nathan D.; Pol, Diego (2007)."Anatomy of a basal sauropodomorph dinosaur from the Early Jurassic Hanson Formation of Antarctica"(PDF).Acta Palaeontologica Polonica.52(4): 657–674.[permanent dead link]
  35. ^Hammer, W.R.; Hickerson, W.J.; Slaughter, R.W. (1994)."A dinosaur assemblage from the Transantarctic Mountains"(PDF).Antarctic Journal of the United States.29(5): 31–32.
  36. ^Smith, Nathan D. (2013). "New Dinosaurs from the Early Jurassic Hanson Formation of Antarctica, and Patters of Diversity and Biogeography in Early Jurassic Sauropodomorphs".Geological Society of America Abstracts with Programs.45(7): 897.
  37. ^Bomfleur, B.; Schneider, J. W.; Schöner, R.; Viereck-Götte, L.; Kerp, H. (2011)."Fossil sites in the continental Victoria and Ferrar groups (Triassic-Jurassic) of north Victoria Land, Antarctica".Polarforschung.80(2): 88–99.Retrieved15 November2021.
  38. ^Musumeci, G.; Pertusati, P. C.; Ribecai, C.; Meccheri, M. (2006)."Early Jurassic fossiliferous black shales in the Exposure Hill Formation, Ferrar Group of northern Victoria Land, Antarctica".Terra Antartica Reports.12(1): 91–98.Retrieved17 November2021.
  39. ^abcBomfleur, B.; Pott, C.; Kerp, H. (2011)."Plant assemblages from the Shafer Peak Formation (Lower Jurassic), north Victoria Land, Transantarctic Mountains".Antarctic Science.23(2): 188–208.Bibcode:2011AntSc..23..188B.doi:10.1017/S0954102010000866.S2CID130084588.
  40. ^Bomfleur, B.; Blomenkemper, P.; Kerp, H.; McLoughlin, S. (2018)."Polar regions of the Mesozoic–Paleogene greenhouse world as refugia for relict plant groups"(PDF).Transformative Paleobotany.15(1): 593–611.doi:10.1016/B978-0-12-813012-4.00024-3.Retrieved13 February2022.
edit