Dromornis murrayi

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Dromornis murrayi
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: †Gastornithiformes
Family: †Dromornithidae
Genus: †Dromornis
Species:
†D. murrayi
Binomial name
†Dromornis murrayi
Worthy, et al.[1]

Dromornis murrayi was a species of dromornithid, extinct flightless birds known as mihirungs. It was described in 2016 using specimens discovered amongst the Riversleigh fauna in Queensland, Australia. The period during which it existed was the oligocene to early miocene, making this the earliest known species of the genus Dromornis. The size of these mihirungs was also determined to be the smallest of its genus. Dromornis murrayi was described from specimens of cranial and post cranial material.[1]

Taxonomy[]

Dromornis murrayi was described in 2016 as new species. The type material is the partial remains of a cranium, which was obtained at a locality named Hiatus A Site in the Carl Creek Limestone Formation; this location is one of the numerous study sites at the Riversleigh World Heritage Area.[2] The specimens were discovered by two of the collaborating authors, Michael Archer and Suzanne J. Hand, the head researchers of taxa at the celebrated Riversleigh site and its associated fauna.[3]

The birds are the first in an apparent succession of species, the smallest of the Dromornis lineage that culminated in the gigantic 'thunderbird' D. stirtoni then the poorly known D. australis.[4]

The placement of this dromornithid species may be summarised as

Dromornithidae (8 species in 4 genera)[4]

Description[]

This species stood around 1.5 metres high and weighed up to 250 kilograms, a considerable size but smaller than its congeners; the later species Dromornis stirtoni is determined to have been up to 650 kilograms. The fossil specimens used to describe Dromornis murrayi have been dated to 26 million years ago, being discovered at a 'shelf', a rich layer of fossilised bones, that included leg and cranial remains of the unknown species.[3]

Wings were greatly reduced, approximately 100 – 150 millimetres, and would not have been evident beneath the bird's plumage. The skull cavity held an exceptionally small brain, the description's leading author Trevor Worthy suggesting the comparison, "I mean, if a chicken was silly, these things were very much more silly."[3]

Distribution[]

The fossil deposits of Dromornis murrayi at the Hiatus site of Riversleigh have been dated as early Miocene and another as late Oligocene to early Miocene. This was established using correlation with the evolutionary stage of vertebrate species known from other sites at Riversleigh. Hiatus site is limestone deposited in an aquatic setting, lacking indicators for methods such as radiometric dating. Another site where the species occurs is Cadbury's Kingdom, designated as Faunal Zone B which is also dated as early Miocene. The temporal range of these finds is approximately 25 to 16 mega-annum.[4]

The only known occurrence of this species is amongst the Riversleigh fauna, the site is located in the northeastern region of the Australian continent.[4]

References[]

  1. ^ a b c Worthy, Trevor H.; ; Archer, Michael; Hand, Suzanne J. (3 May 2016). "The extinct flightless mihirungs (Aves, Dromornithidae): cranial anatomy, a new species, and assessment of Oligo-Miocene lineage diversity". Journal of Vertebrate Paleontology. 36 (3). doi:10.1080/02724634.2015.1031345.
  2. ^ "Fossilworks: Dromornis murrayi". fossilworks.org. Retrieved 17 December 2021.
  3. ^ a b c Brennan, Imogen (19 February 2016). "Bones from ancestor of 'giant duck' discovered in Australia". PM. www.abc.net.au.
  4. ^ a b c d Handley, Warren D.; Worthy, Trevor H. (15 March 2021). "Endocranial Anatomy of the Giant Extinct Australian Mihirung Birds (Aves, Dromornithidae)". Diversity. 13 (3): 124. doi:10.3390/d13030124.
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