Steropodon is a genus of prehistoric monotreme, or egg-laying mammal. It contains a single species, Steropodon galmani, that lived about 105 to 93.3 million years ago (mya) in the Early to Late Cretaceous period. It is one of the oldest monotremes discovered, and is one of the oldest Australian mammal discoveries.
Model of Steropodon galmani at the Australian Museum, Sydney
The dentition of Steropodon is somewhat similar to that of therians—the placentals and the marsupials—specifically the presence of the tribosphenic molar tooth which was thought to be exclusive to therians since the Cretaceous. This, along with the tribosphenic molar discoveries of monotreme-relatives Ausktribosphenos and Ambondro mahabo of which the latter evolved in the Jurassic, led to the conclusion that the molar evolved independently in the two lineages. This inspired the creation of the subclassesAustralosphenida—the monotremes and extinct relatives—and Tribosphenida—placentals and marsupials. However, given this classification is based only on jaw and lower-tooth remains, insufficient evidence may exist to definitively make this conclusion.[2]
It may be only described member of the family Steropodontidae. Another proposed member is Teinolophos that was moved into its own family, Teinolophidae, by Flanneryet al. (2022).[3] Edentulous partial mandible from the Finch Clay facies of the Griman Creek Formation was attributed to undescribed steropodontid by Musser (2013).[4] On other side, Flannery et al. assumed that this mandible may belong to a new genus and species of stemornithorhynchid.[3]
The specific epithet is derived from the surname of the jaw's collectors, when combined with the genus name Steropodon is intended to translate as "Galman's lightning tooth".[5]
Description
The Steropodon jaw on display at the American Museum of Natural History, New York City, USA
Steropodon is known only from a single opalisedjaw with three molars, discovered at the Griman Creek Formation, Lightning Ridge, New South Wales, Australia, by brothers David and Alan Galman. It was a large mammal for the Mesozoic, being 40–50 centimetres (16–20 in) long. The lower molars are 5–7 millimetres (0.20–0.28 in) in length, with a width of 3–4 millimetres (0.12–0.16 in). A length of 1–2 centimetres (0.39–0.79 in) is more typical for Mesozoic mammals.[6]
Woodburne (2003, p. 212) reports that the holotype is a right mandible named AM F66763. The preserved molars are m1–m3. Examination of the jaw fragment revealed a mandibular canal, which has been proposed to indicate the presence of a bill, similar to those of the extinct species Obdurodon dicksoni and the modern platypus Ornithorhynchus anatinus.
^Bell, Phil R.; Fanti, Federico; Hart, Lachlan J.; Milan, Luke A.; Craven, Stephen J.; Brougham, Thomas; Smith, Elizabeth (2019). "Revised geology, age, and vertebrate diversity of the dinosaur-bearing Griman Creek Formation (Cenomanian), Lightning Ridge, New South Wales, Australia". Palaeogeography, Palaeoclimatology, Palaeoecology. 514: 655–671. Bibcode:2019PPP...514..655B. doi:10.1016/j.palaeo.2018.11.020. hdl:11585/651841. S2CID 134264936.
^Stokstad, E. (2001). "Tooth theory revises history of mammals". Science. 291 (5501): 26. doi:10.1126/science.10.1126/SCIENCE.291.5501.26. PMID 11191993. S2CID 6297739.
^ abFlannery, T. F.; Rich, T. H.; Vickers-Rich, P.; Ziegler, T.; Veatch, E. G.; Helgen, K. M. (2022). "A review of monotreme (Monotremata) evolution". Alcheringa: An Australasian Journal of Palaeontology. 46: 3–20. doi:10.1080/03115518.2022.2025900. S2CID 247542433.
^Musser, A. M. (2013). "Classification and evolution of the monotremes". In Ashwell, K. (ed.). Neurobiology of Monotremes: Brain Evolution in Our Distant Mammalian Cousins. Melbourne: CSIRO Publishing. pp. 1–17. ISBN9780643103153.
^M. Archer, F. A. Jenkins, S. J. Hand, P. Murray, and H. Godthelp. 1992. Description of the skull and non-vestigial dentition of a Miocene platypus (Obdurodon dicksoni n. sp.) from Riversleigh, Australia, and the problem of monotreme origins. Platypus and Echidnas 15-27.
^Archer, M.; Flannery, T. F.; Ritchie, A.; Molnar, R. E. (1985). "First Mesozoic mammal from Australia — an early Cretaceous monotreme". Nature. 318 (6044): 363–366. Bibcode:1985Natur.318..363A. doi:10.1038/318363a0. S2CID 4342084.
Further reading
Mackness, Brian, Prehistoric Australia, Sydney, Golden Press, 1987.
steropodon, genus, prehistoric, monotreme, laying, mammal, contains, single, species, galmani, that, lived, about, million, years, early, late, cretaceous, period, oldest, monotremes, discovered, oldest, australian, mammal, discoveries, temporal, range, albian. Steropodon is a genus of prehistoric monotreme or egg laying mammal It contains a single species Steropodon galmani that lived about 105 to 93 3 million years ago mya in the Early to Late Cretaceous period It is one of the oldest monotremes discovered and is one of the oldest Australian mammal discoveries SteropodonTemporal range Albian Cenomanian 105 93 3 Ma 1 PreꞒ Ꞓ O S D C P T J K Pg NScientific classificationKingdom AnimaliaPhylum ChordataClass MammaliaOrder MonotremataFamily SteropodontidaeGenus SteropodonArcher Flannery Ritchie amp Molnar 1985Species S galmaniBinomial name Steropodon galmaniArcher Flannery Ritchie amp Molnar 1985 Contents 1 Taxonomy 2 Description 3 See also 4 References 5 Further reading 6 External linksTaxonomy Edit Model of Steropodon galmani at the Australian Museum Sydney The dentition of Steropodon is somewhat similar to that of therians the placentals and the marsupials specifically the presence of the tribosphenic molar tooth which was thought to be exclusive to therians since the Cretaceous This along with the tribosphenic molar discoveries of monotreme relatives Ausktribosphenos and Ambondro mahabo of which the latter evolved in the Jurassic led to the conclusion that the molar evolved independently in the two lineages This inspired the creation of the subclasses Australosphenida the monotremes and extinct relatives and Tribosphenida placentals and marsupials However given this classification is based only on jaw and lower tooth remains insufficient evidence may exist to definitively make this conclusion 2 It may be only described member of the family Steropodontidae Another proposed member is Teinolophos that was moved into its own family Teinolophidae by Flannery et al 2022 3 Edentulous partial mandible from the Finch Clay facies of the Griman Creek Formation was attributed to undescribed steropodontid by Musser 2013 4 On other side Flannery et al assumed that this mandible may belong to a new genus and species of stem ornithorhynchid 3 The specific epithet is derived from the surname of the jaw s collectors when combined with the genus name Steropodon is intended to translate as Galman s lightning tooth 5 Description Edit The Steropodon jaw on display at the American Museum of Natural History New York City USA Steropodon is known only from a single opalised jaw with three molars discovered at the Griman Creek Formation Lightning Ridge New South Wales Australia by brothers David and Alan Galman It was a large mammal for the Mesozoic being 40 50 centimetres 16 20 in long The lower molars are 5 7 millimetres 0 20 0 28 in in length with a width of 3 4 millimetres 0 12 0 16 in A length of 1 2 centimetres 0 39 0 79 in is more typical for Mesozoic mammals 6 Woodburne 2003 p 212 reports that the holotype is a right mandible named AM F66763 The preserved molars are m1 m3 Examination of the jaw fragment revealed a mandibular canal which has been proposed to indicate the presence of a bill similar to those of the extinct species Obdurodon dicksoni and the modern platypus Ornithorhynchus anatinus See also EditFossil monotremesReferences Edit Bell Phil R Fanti Federico Hart Lachlan J Milan Luke A Craven Stephen J Brougham Thomas Smith Elizabeth 2019 Revised geology age and vertebrate diversity of the dinosaur bearing Griman Creek Formation Cenomanian Lightning Ridge New South Wales Australia Palaeogeography Palaeoclimatology Palaeoecology 514 655 671 Bibcode 2019PPP 514 655B doi 10 1016 j palaeo 2018 11 020 hdl 11585 651841 S2CID 134264936 Stokstad E 2001 Tooth theory revises history of mammals Science 291 5501 26 doi 10 1126 science 10 1126 SCIENCE 291 5501 26 PMID 11191993 S2CID 6297739 a b Flannery T F Rich T H Vickers Rich P Ziegler T Veatch E G Helgen K M 2022 A review of monotreme Monotremata evolution Alcheringa An Australasian Journal of Palaeontology 46 3 20 doi 10 1080 03115518 2022 2025900 S2CID 247542433 Musser A M 2013 Classification and evolution of the monotremes In Ashwell K ed Neurobiology of Monotremes Brain Evolution in Our Distant Mammalian Cousins Melbourne CSIRO Publishing pp 1 17 ISBN 9780643103153 M Archer F A Jenkins S J Hand P Murray and H Godthelp 1992 Description of the skull and non vestigial dentition of a Miocene platypus Obdurodon dicksoni n sp from Riversleigh Australia and the problem of monotreme origins Platypus and Echidnas 15 27 Archer M Flannery T F Ritchie A Molnar R E 1985 First Mesozoic mammal from Australia an early Cretaceous monotreme Nature 318 6044 363 366 Bibcode 1985Natur 318 363A doi 10 1038 318363a0 S2CID 4342084 Further reading EditMackness Brian Prehistoric Australia Sydney Golden Press 1987 External links EditSteropodon at Fossilworks Data related to Steropodon at Wikispecies Media related to Steropodon at Wikimedia CommonsPortals Paleontology Prehistoric mammals Retrieved from https en wikipedia org w index php title Steropodon amp oldid 1149570573, wikipedia, wiki, book, books, library,
