Thylacinus yorkellus
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| Thylacinus yorkellus Temporal range: Late Miocene or Early Pliocene | |
|---|---|
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| Holotype left dentary | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Infraclass: | Marsupialia |
| Order: | Dasyuromorphia |
| Family: | †Thylacinidae |
| Genus: | †Thylacinus |
| Species: | †T. yorkellus |
| Binomial name | |
| †Thylacinus yorkellus Yates, 2015 | |
Thylacinus yorkellus is an extinct species of carnivorous marsupial from South Australia that lived during the Late Miocene or Early Pliocene. It is sister species to the recently extinct Thylacinus cynocephalus, the Tasmanian tiger, both of which existed on mainland Australia.
In 1992, Neville Pledge briefly reported on an incomplete left dentary (SAM P29807) of a thylacinid from the Curramulka Local Fauna of Corra-Lynn Cave, South Australia. Pledge remarked on the possibility of a new species but decided not to name it.[1] Following the discovery of additional remains, Adam Yates, in 2015, made the jaw bone the holotype specimen of the new species Thylacinus yorkellus. An isolated right lower third molar (SAM P38799) was made the paratype.[2]
The specific epithet combines the name of the region it was discovered, the Yorke Peninsula, and the Latin ellus, a diminutive suffix that denotes a species that was smaller than Thylacinus cynocephalus.[2]
Description
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Thylacinus yorkellus is characterised by two autapomorphies: the lower molars possess a precingulid that ends in a cuspidule on the anterobuccal (nearest to the front of the cheek) face of the paraconid; and a majority of the premolars and molars have a small, forward facing cuspidule.[2]
The dentary retains three premolars, two molars, a canine and an incisor alveoli. It is compressed transversely (from side to side) and lacks a torus on the ventrobuccal margin. Three small openings called mental foramina can be seen from the side of the jaw, located below the second premolar, and the second and third molar respectively. A wide gap (diastema) is present between each of the premolars as well as between the third premolar and first molar. The canine is angled vertically and slightly recurves lingually (towards the tongue) at the tip. The premolars gradually increase in size towards the back of the dentary. All of the molars have a deep, strongly-developed carnassial notch. Unlike in more basal taxa, the molars of T. yorkellus lack metaconids.[2]
Yates (2015) calculated the weight for two known specimens using regression functions applied to dasyuromorphian data. The holotype and paratype are noted as being 17.8 kg (39 lbs) and 15.9 kg (35 lbs) respectively.[2] Rovinsky et al. (2019), however, gave a lower estimate of 14.5 kg (32 lbs) for the paratype.[3]
