Steropodon galmani (lat.) - a species of extinct mammals from the family of platypus (Ornithorhynchidae) order of single pass (Monotremata), who lived in the Lower Cretaceous era ( Albanian century ) in Australia . Type and only species of the genus Steropodon [1] .
| † Steropodon galmani | |||||||||||||||||||||||||||||||||||||||||
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 One of the possible reconstructions of the appearance. Australian Museum , Sydney | |||||||||||||||||||||||||||||||||||||||||
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Steropodon galmani | |||||||||||||||||||||||||||||||||||||||||
| Geochronology Albanian age 113.0-100.5 Ma
◄ Nowadays◄ Cretaceous-Paleogene extinction◄ Triassic extinction◄ Mass Permian Extinction◄ Devonian extinction◄ Ordovician-Silurian extinction◄ Cambrian explosion | |||||||||||||||||||||||||||||||||||||||||
Content
- 1 Study History
- 2 Description
- 3 Systematics
- 4 notes
- 5 Literature
Study History
The view is known one at a time.a fragmented lower jaw fragment with three molar m1 – m3 found in the Griman Creek Formation , New South Wales , Australia, by the brothers David and Alan Galman, in whose honor the animal received the specific name galmani . The generic name Steropodon is derived from other Greek. στέροψ ὀδούς - “sparkling tooth”.
Description
According to estimates, Steropodon reached a length of 40-50 cm, which is large for Mesozoic mammals. The lower molars are 5–7 mm long and 3-4 mm wide, while the mammals of that era are typically 1–2 cm long. From the same formation, a find of another one-pass is known — Kollikodon ritchiei .
The mandibular canal probably indicates the presence of a beak, like the fossil platypus obdurodon , and the modern platypus . The molars of the steropodon in their tribosthenic structure are very similar to the molars of the living teria animals ( Theria ), and nevertheless, there are some differences. Steropodon did not have entoconide (the main tubercle on the lingual part of the crown of the lower molars), and by the absence of characteristic wear, we can conclude that there was no protocone on the upper molars (a tubercle similar to entoconid). This confirms the double origin of tribosphenic type teeth, independently in the group of animals (actually tribosphenic teeth) and in the group of single pass (pseudotribosphenic teeth).
Systematics
Scientists have not come to a final conclusion about the position of the genus Steropodon in the subclass of primitives . A group of paleontologists who described the species in 1985 placed it in the platypus family (Ornithorhynchidae) [2] . In 1995, the genus was separated into a separate family of Steropodontidae Flannery et al. , 1995 , and in 2002, in the treasure of Australosphenida , which made the genus more primitive than the detachment of monotremes (Monotremata) [1] . The work of Rowe et al. 2008 rejected the treasure of Australosphenida, returning the Steropodon taxon to its original position - the platypus family [3] .
Notes
- ↑ 1 2 Steropodon galmani (English) information on the Paleobiology Database website. (Retrieved December 5, 2018) .
- ↑ Archer et al., 1985 , p. 363-366.
- ↑ Rowe T., Rich TH, Vickers-Rich P., Springer M., and Woodburne MO The oldest platypus and its bearing on divergence timing of the platypus and echidna clades // Proceedings of the National Academy of Sciences. - 2008. - Vol. 105, no. 4. - P. 1238-1242.
Literature
- Archer M., Flannery TF, Ritchie A., Molnar RE First Mesozoic mammal from Australia - an early Cretaceous monotreme // Nature. - 1985. - Vol. 318. - P. 363-366.