Paleontologists have unearthed a well-preserved, almost complete left frontal (part of the skull roof) of a previously unknown species of megaraptorid dinosaur in the upper Strzelecki Group (earliest Cretaceous) of Victoria, Australia. The new specimen provides limited support for the hypothesis that megaraptorid dinosaurs might have originated in Australia.
Kotevski et al. report the first evidence of non-mandibular skull material of a non-avian theropod from Australia: a left frontal and fused parietal fragment from the Lower Cretaceous upper Strzelecki Group of Victoria. Image credit: Kotevski et al., doi: 10.1016/j.cretres.2023.105769.
Megaraptoridae is a family of theropods that lived in different regions of Gondwana during the Cretaceous period.
These carnivorous dinosaurs had large hand claws and robust forelimbs, which were usually reduced in size in other large theropods.
“The Australian Cretaceous non-avian theropod record is poorly understood when compared with that of most other continents, as it almost exclusively comprises isolated postcranial remains,” Monash University paleontologist Jake Kotevski and his colleagues wrote in their paper.
“Only four specimens described to date comprise associations of multiple elements: a pair of theropod pubic bones from the lower Albian Eumeralla Formation; the megaraptorid dubbed ‘Lightning Claw’ from the Cenomanian Griman Creek Formation; and an unnamed megaraptorid and the holotype specimen of Australovenator wintonensis from the Cenomanian Winton Formation.”
“Three of these four specimens have been referred to the Megaraptoridae, the group of theropods to which the vast majority of diagnostic theropod remains in Australian mid-Cretaceous dinosaur assemblages can be referred.”
The new megaraptorid specimen was unearthed at the locality of Shack Bay of the Lower Cretaceous upper Strzelecki Group (informally known as the Wonthaggi Formation) in Victoria, Australia.
The find was made by Michael Cleeland of the volunteer organization Dinosaur Dreaming in 2007.
The fossil dates back 120 million years old and improves the limited record of Cretaceous Australian theropod skull remains.
It also provides limited support for the hypothesis that Megaraptoridae might have originated in Australia.
“The specimen constitutes the first non-mandibular cranial element from a non-avian theropod to be reported from Australia,” the paleontologists wrote.
“It represents the geologically oldest megaraptorid skull element worldwide, and emphasizes the prevalence of this theropod group in the mid-Cretaceous of Australia.”
“The results of our analyses support referral of this specimen to the clade Megaraptoridae,” they added.
“However, additional megaraptoran cranial remains will be required to clarify both the phylogenetic position of the species and the interrelationships within Megaraptora.”
The team’s paper was published this month in the journal Cretaceous Research.
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Jake Kotevski et al. A megaraptorid (Dinosauria: Theropoda) frontal from the upper Strzelecki Group (Lower Cretaceous) of Victoria, Australia. Cretaceous Research, published online November 2, 2023; doi: 10.1016/j.cretres.2023.105769
