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Eastern Grey Kangaroo (skeletal remains)

Macropus giganteus giganteus

Description:

On a recent hike at Girraween, I found the skeletal remains of an "eastern grey kangaroo" - Macropus giganteus giganteus. I thought initially it may have been a "common wallaroo" - Macropus robustus, one of the other macropod species found in this national park, but it turned out not to be the case. Upon closer inspection, the wallaroo has a slightly stockier skull, but it was also dentitian that helped here. The distance between the incisors, canines and molars, called the 'diastema' (plural diastemata), is quite large in herbivores, and is larger in the eastern grey than it is the wallaroo. It's the most obvious visible difference that I could see, whereas other aspects of the skull are, at first glance, almost identical. Here's a wallaroo skull for comparison.... https://collections.museumsvictoria.com.... NB: Kangaroos and wallabies do not have canine teeth, hence the diastema of my spotting is noticeably large, seen very clearly in the 2nd photo. Incisors are also well-developed in grazing animals. Other species to be found here are the "swamp wallaby" - Wallabia bicolor, and "red-necked wallaby" - M. rufogriseus, but I could rule both out immediately due to the absence of two large holes in the palate of the skull, called 'palatine-maxillary vacuities'.... https://peerj.com/articles/6099/#fig-6 (compare images D and H with E). My previous investigations into kangaroo anatomy seem to have been beneficial after all. This spotting was interesting for a number of reasons, least of which was its age, and how many pieces of the skeleton had remained in such a small area despite it. The bones were completely sun-bleached and brittle (note the shattered mandible - 5th photo), and absent of any sinew or hide whatsoever. I would attribute bushfires as being the most likely cause of this, the most recent of which was last year. I managed to locate the skull and mandible, ribs and various thoracic and lumbar vertebrae, both pelvic bones, femurs, tibias and fibulas, plus an assortment of other bones which I'm unfamiliar with. I was hoping to find intact forepaws and feet, particularly the claws of both, but alas they were not to be found, more's the pity because they are very distinctive parts of the animal. Perhaps they were scattered farther afield.

Habitat:

Spotted in a small clearing along a fire trail, near the Mt. Norman day use area in Girraween National Park, SEQ. Dry sclerophyll forest on sandy granite soils, and some areas thinned of trees, with smaller shrubs and native grasses... which kangaroos and wallabies love! Here's some park info - http://www.rymich.com/girraween/ https://en.wikipedia.org/wiki/Girraween_...

Notes:

(1) Excellent information on macropods - Section 2.2 Dentition, and figure 7.1 - https://veteriankey.com/macropods/ (2) The macropodid dental formula - https://animaldiversity.org/accounts/Mac... (3) An interesting skull comparison between a wallaby (definitely red-necked) and a juvenile red kangaroo - https://shadyufo.tumblr.com/post/1432968... (4) Good image of full skull (including mandible) - https://www.researchgate.net/figure/Faci... (5) Top, bottom and lateral views of full skull - https://collections.museumvictoria.com.a...

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8 Comments

Neil Ross
Neil Ross a year ago

Thanks, Maria. I'm really enjoying osteology. It is fascinating!

Maria dB
Maria dB a year ago

Very interesting!

Neil Ross
Neil Ross a year ago

Thank you, Mark and Leuba. I appreciate the nomination.

Leuba Ridgway
Leuba Ridgway a year ago

Brilliant and very interesting spotting Neil. Thanks.

Mark Ridgway
Mark Ridgway a year ago

Your spotting has been nominated for the Spotting of the Week. The winner will be chosen by the Project Noah Rangers based on a combination of factors including: uniqueness of the shot, status of the organism (for example, rare or endangered), quality of the information provided in the habitat and description sections. There is a subjective element, of course; the spotting with the highest number of Ranger votes is chosen. Congratulations on being nominated!

Mark Ridgway
Mark Ridgway a year ago

Super spotting. Great info.

Neil Ross
Neil Ross a year ago

Thanks, Brian. I love spotting stuff like this, and it's always so interesting to research and to look at animals from a totally different perspective. Osteology is a fascinating science!

Brian38
Brian38 a year ago

Great spotting, Neil! Fascinating and interesting notes as always!

Neil Ross
Spotted by
Neil Ross

Wallangarra, Queensland, Australia

Spotted on Jul 20, 2020
Submitted on Aug 1, 2020

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