Palorchestes
Palorchestes ("ancient leaper or dancer") is an extinct genus of terrestrial, herbivorous marsupials of the family Palorchestidae. The genus was endemic to Australia, living from the Miocene through to the Pleistocene epochs.
The generic name was coined in 1873 by anatomist Richard Owen, who first found what he thought was the fragmentary jaw of a prehistoric kangaroo and derived the name from ancient Greek terms for "ancient" and "leaper".[1] Despite Owen explicitly stating the etymology of the name in his description, palaeontologist Harold Fletcher published a translation as "the ancient dancer" in 1945.[2] When more postcranial elements were found, Palorchestes was realized as not a macropod, but a diprotodontid.[3] Owen's description as a giant kangaroo was revised in 1958 by Jack T. Woods of the Queensland Museum, allying the genus to the Diprotodontia order.[4]
Another genus is probably ancestral to these species, thus named Propalorchestes; it shared some characteristics of the molars, but had shorter jaws and therefore snout.
The fossil dentary of a young adult found in Pleistocene deposits in the Darling Downs region of southeast Queensland, although limited by the rarity of specimens and comparable remains of the genus, was distinguishable from P. azael, P. parvus, and P. painei. The specimen provides evidence of sympatry with another species of the genus, rather than the apparent sequence of form and size from the mid-Miocene to recent era, and may represent a new species or sexual dimorphism in a smaller species.[9]
The genus was allied to other diprotodontid genera, Ngapakaldia and Pitikantia, firstly recognised as a subfamily Palorchestinae (Stirton, 1967), later elevated to familial status with the order (Archer and Bartholomai, 1978).[2]
Palorchestes azael, was similar in size to a horse, being around 2.5 m (8.2 ft) in length, with quantitative body mass estimates based on humerus and femur bones indicating its body mass could well have exceeded 1,000 kg (2,200 lb).[10] Palorchestes species had four powerful legs, with the front legs bearing large claws, similar to those of a koala, which they probably used to pull down leaves and strip the bark from trees.[11] The long symphysis at the lower jaw of all Palorchestes species indicates that their tongues were long and protrudible, like that of a giraffe.[3] The appearance of the animals' nasal bones suggests that they possessed a short proboscis,[5] leading to the nickname of the "marsupial tapir". However, a recent study that reviewed the cranial morphology of various Palorchestes species and the related genus of Propalorchestes showed strong support for well-developed prehensile lips, rather than a tapir-like proboscis.[12]
