Ekaltadeta

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Ekaltadeta
Life reconstruction by Ekaltadeta ima

Life reconstruction by Ekaltadeta ima

Temporal occurrence
Miocene
23.03 to 5.333 million years
Locations
Systematics
Australidelphia
Diprotodontia
Kangaroo-like (Macropodoidea)
Hypsiprymnodontidae
Propleopinae
Ekaltadeta
Scientific name
Ekaltadeta
Archer & Flannery , 1985
species
  • E. ima Archer & Flannery , 1985
  • ? E. jamiemulvaneyi Wroe , 1996

Ekaltadeta is an extinct marsupial - species from the super family of kangaroo-like (Macropodoidea). It lived in northeast Australia in the Miocene eraand is considered an at least occasional carnivore and predator due to its teeth.

Origin of name (etymology)

The generic name comes from the Aboriginal language of the MacDonnell Ranges and means something like "strong teeth". It was coined in 1985 by the Australian vertebrate paleontologists Michael Archer and Timothy Flannery .

features

Plagiaulacoid premolars of various mammals (mainly multituberculates), P3 from Ekaltadeta at the bottom, 3rd from left

Namely (see above) and in particular diagnostic for the genus are the extremely large third premolars (premolars) in the lower and upper jaw. The crown of both premolars (i.e. P2 and P3) is, as in closely related genera, "fluted" and equipped with a serrated serrated cutting edge. Such formed premolars are called plagiaulacoid and are found convergent among others in the Multituberculata , late Mesozoic mammals of uncertain systematic position. The P3 only erupts at the transition to adult life. The P2 remains in the dentition afterwards, but loses its functionality. Further diagnostic are u. a. the dagger-like incisors (incisors) of the lower jaw (I 1 ), the only narrow diastem between the incisors and the anterior premolar of the lower jaw (P 2 ) and a decrease in the size of the low- crowned ( brachydont ) molars ("main molars") from the front behind, particularly clearly in the upper jaw. Another characteristic of the molars of the upper jaw is their broad base with a slightly conical shape of the crown. In contrast to the premolars, the molars have relatively large horizontal occlusal surfaces. These are bunodont , i.e. H. they have four rounded main cusps.

The most important non-dental diagnostic criterion of the genus is that approximately at the level of the M 3 of the "Dental channel" * (engl. "Dental canal") side towards the tongue (linguad) from "Masseterkanal" ** branches (engl. "Masseteric canal"), and is separated from the front end of the masseter canal by a buccal bony wall on the cheek side. In all other kangaroo types, the dental canal runs within the masseter canal. The masseter channel ends at Ekaltadeta at the level of the contact area of ​​the P 3 with the M 1 . Other non-dental diagnostic features include: a. a clearly pronounced sagittal ridge ("crown crest") and nuchal ridge (bone crest at the transition from the dorsal and lateral cranial roof to the occiput) as well as a clear interorbital constriction of the skull.

* The "dental canal " (homologous to the mandibular canal of humans?) Is a tube-like canal in the front, tooth-bearing part of the lower jawbone (dental), in which nerves and blood vessels, etc. a. of the masseter muscle .
** The masseter channel is the continuation of the masseter trough ( fossa masseterica ) sunk into the ascending branch at the rear end of the lower jaw into the horizontal, anterior, tooth-bearing branch of the lower jaw bone (dental). The corresponding opening in the anteroventral part of the masseter recess is called the masseter foramen . The masseter canal occurs in several groups of Diprotodont animals and serves as an enlarged attachment surface for the deep part ( pars profunda ) of the masseter muscle.

Diet

Ekaltadeta's dentition appears to be suitable for hunting and for chopping up animal food: the dagger-like elongated lower incisors were possibly used to kill prey, the plagiaulacoid premolars probably made it possible to chop up meat, analogous to the fangs of predatory mammals . The shape of the molars, however, is typical of omnivores or herbivores, so that the genus can be seen as a food opportunist and ecologically somewhere between wild boars and foxes , with "certain tendencies towards carnivory " being assumed. Against a special adaptation to a carnivorous diet, the fact that the condyle of the lower jaw in E. ima is well above the occlusal plane of the molars, whereas in obligatory carnivorous or insectivorous terrestrial vertebrates, the jaw joint is approximately at the same height as this plane.

Systematics

From ekaltadeta far two species have been described. Both are known so far only from different locations of the famous Riversleigh fossil site in Queensland . The type species Ekaltadeta ima Archer & Flannery , 1985 reached the size of a wallaby with a body weight of up to 15 kilograms. Their remains come from deposits of the early to middle Miocene (including those of the "Gag Site" with their local dwornamor fauna). E. jamiemulvaneyi Wroe , 1996 was around half larger and differs from E. ima in a smaller size difference between P3 and the molars, a less significant decrease in the size of the molars of the upper jaw towards the rear end of the row of teeth and in details of the molar morphology (cusp configuration ). It lived after E. ima at the beginning of the late Miocene and belongs to the local encore fauna.

Ekaltadeta is placed together with the genera Jackmahoneya and Propleopus in the purely fossil subfamily Propleopinae , which are also referred to as "giant rat kangaroos". Ekaltadeta is the geologically oldest genus and, with E. ima, is the smallest species of the Propleopinae. However, cladistic relationship analyzes based on morphological data have shown that E. jamiemulvaneyi is more closely related to two Propleopus species than to E. ima . The genus would therefore not be monophyletic and E. jamiemulvaneyi would either have to be assigned to Propleopus or placed in its own genus according to the rules of the phylogenetic system . However, these analyzes are based on a very small data set and their results are therefore not considered to be particularly reliable.

The Propleopinae are now mostly family Hypsiprymnodontidae associated with the musky rat-kangaroo ( Hypsiprymnodon moschatus ) a recent includes type, although were doubts about such close kinship of Propleopinae registered with any extant group and now also confirmed. The Hypsiprymnodontidae in turn stand together with u. a. the "real" kangaroos (Macropodidae) and the rat kangaroos i. e. S. (Potoroidae) in the superfamily of the kangaroo-like (Macropodoidea).

swell

General

  • John A. Long, Michael Archer, Timothy Flannery, Suzanne Hand: Prehistoric Mammals of Australia and New Guinea. Johns Hopkins University Press, Baltimore 2003, ISBN 0-8018-7223-5 , p. 151 ff.

Individual evidence

  1. ↑ a b Michael Archer, Timothy Flannery: Revision of the extinct gigantic rat kangaroos (Potoroidae: Marsupialia), with description of a new Miocene genus and species and a new Pleistocene species of Propleopus (Australia). Journal of Paleontology. Vol. 59, No. 6, 1985, pp. 1331-1349 ( JSTOR 1304948 ; alternative full text access : ResearchGate )
  2. ↑ a b c d Stephen Wroe: An investigation of phylogeny in the giant extinct rat kangaroo Ekaltadeta (Propleopinae, Potoroidae, Marsupialia). Journal of Paleontology. Vol. 70, No. 4, 1996, pp. 681-690 ( JSTOR 1306529 ; alternative full-text link : UNSW PDF 2.47 MB).
  3. ↑ Thomas H. Rich, Patricia Vickers-Rich, Timothy F. Flannery, Benjamin P. Kear, David J. Cantrill, Patricia Komarower, Lesley Kool, David Pickering, Peter Trusler, Steven Morton, Nicholas van Klaveren, Erich MG Fitzgerald: An Australian multituberculate and its palaeobiogeographic implications. Acta Palaeolontologica Polonica. Vol. 54, No. 1, 2009, pp. 1-6, doi: 10.4202 / app.2009.0101 (Open Access).
  4. ↑ a b c Stephen Wroe, Jenni Brammall, Bernard N. Cooke: The Skull of Ekaltadeta ima (Marsupialia, Hypsiprymnodontidae?): An Analysis of Some Marsupial Cranial Features and a Re-Investigation of Propleopine Phylogeny, with Notes on the Inference of Carnivory in Mammals. Journal of Paleontology. Vol. 72, No. 4, 1998, pp. 738-751 ( JSTOR 1306699 ; alternative full-text link : UNSW PDF 2.47 MB).
  5. ↑ a b A. A. Abbie: A masticatory adaptation peculiar to some diprotodont marsupials. Journal of Zoology. Bd. B109, No. 1, 1939, pp. 261-279, doi: 10.1111 / j.1096-3642.1939.tb00716.x
  6. ↑ Natalie M. Warburton: Comparative jaw muscle anatomy in kangaroos, wallabies, and rat-kangaroos (Marsupialia: Macropodoidea). The Anatomical Record. Vol. 292, No. 6, 2009, pp. 875–884, doi: 10.1002 / ar.20905 (Open Access)
  7. ↑ "distinct leanings towards carnivory," Long et al., 2003 (see general sources )
  8. ↑ Stephen Wroe: Australian marsupial carnivores: Recent advances in palaeontology. Pp. 102-123 in: Menna Jones, Chris R. Dickman, Michael Archer (Eds.): Predators with Pouches: The Biology of Marsupial Carnivores. CSIRO Publishing, Collingwood 2003, ISBN 0-643-06634-9 (full text of the chapter: UNSW ), p. 118
  9. ↑ Stephen Wroe: Stratigraphy and phylogeny of the giant extinct Rat-kangaroos (Propleopinae, Hypsiprymnodontidae, Marsupialia). Memoirs of the Queensland Museum. Vol. 41, No. 2, 1997, pp. 449-456 ( BHL ).
  10. ^ Benjamin P. Kear, Bernard N. Cooke, Michael Archer, Timothy F. Flannery: Implications of a new species of the Oligo-Miocene kangaroo (Marsupialia: Macropodoidea) Nambaroo, from the Riversleigh World Heritage Area, Queensland, Australia. Journal of Paleontology. Vol. 81, No. 6, 2007, pp. 1147–1167, doi: 10.1666 / 04-218.1 (alternative full text access : ResearchGate )