First ceratosaurian dinosaur from Australia

Abstract

The basal theropod dinosaur clade Ceratosauria, and its subclade Abelisauroidea, is characteristic of late Mesozoic terrestrial vertebrate faunas in western Gondwana (South America, Africa, Madagascar, and India) and Europe. Yet unambiguous records of ceratosaurs have hitherto been absent from Australia, where the theropod assemblage appears to include several typically Laurasian clades. Here, we report the first evidence of ceratosaurs (and potentially abelisauroids) from eastern Gondwana--a diagnostic astragalocalcaneum from the Aptian (121-125 Ma) of Victoria, Australia. Ceratosauria thus occurred in both western and eastern Gondwana during the Early Cretaceous. This fossil adds to the poorly known dinosaur fauna of Australia, a major clade of basal theropods, emphasising that its mid-Cretaceous theropod diversity was surprisingly cosmopolitan despite relative geographic isolation, including clades that have been thought to be typical of both Gondwana and Laurasia--Ceratosauria, Spinosauridae, Carcharodontosauria, Tyrannosauroidea, and Deinonychosauria. Such a contemporaneous association of theropod clades is unknown from other Gondwanan continents and questions the views that the late Mesozoic dinosaur fauna of Australia was dominated by Gondwanan or Laurasian elements, extreme isolation, relictualism, and/or novelty as a 'centre of origin'. The cosmopolitan theropod fauna of Australia probably reflects the global distribution of these clades early in their history, prior to significant continental breakup.

Phylogenetic relationships of the Cretaceous Gondwanan theropods Megaraptor and Australovenator: the evidence afforded by their manual anatomy

“…After a comprehensive phylogenetic analysis, these authors considered megaraptorans as allosauroids closely related with carcharodontosaurid theropods, an interpretation subsequently followed by later authors (Carrano et al, 2012;Zanno and Makovicky, 2013). However, recent studies conducted by some of us (e.g., Novas et al, 2013;Porfiri et al, 2014) have suggested that megaraptorans are not representative of archaic allosauroid tetanurans, but instead argued that megaraptorans are coelurosaurs, and representatives of a basal tyrannosauroid radiation in particular (Novas et al, 2013).…”

“…Additional evidence of the presence of megaraptorids in regions of South America other than Argentina comes from Brazil, from which isolated caudal vertebrae have been described (Mendez et al, 2013). Cretaceous formations of Australia have yielded several isolated elements referred to Megaraptoridae, including Rapator ornitholestoides (Huene, 1932;Agnolín et al, 2010;White et al, 2012), an isolated ulna closely similar to that of Megaraptor and Australovenator (Smith et al, 2008), more than one hundred isolated teeth (Benson et al, 2012), and probably an isolated astragalus (Molnar et al, 1981;Fitzgerald et al, 2012), and paired pubes originally described as tyrannosauroid (Benson et al, 2010b;Novas et al, 2013).…”

Filling the ceratosaur gap: A new ceratosaurian theropod from the Early Cretaceous of Spain

“…. There are also various disputed Early Cretaceous (Aptian-Albian) possible ceratosaur remains from Australia (reviewed by , and a definite ceratosaur astragalus (Fitzgerald et al 2012).…”

Birds and hard ticks (Acari: Ixodidae), with discussions about hypotheses on tick evolution

“…Dietrich et al (2014) dated the split of I. uriae and I. holocyclus when Australia and Antarctic was still connected and available mammal hosts there were monotremes (Archer et al, 1985;Musser, 2003). Avialae was established by early Cretaceous in Australasia (Chiappe, 1996;Close et al, 2009;Fitzgerald et al, 2012;Martin et al, 2014) and by late Cretaceous in Antarctica (Chiappe, 1996;Clarke et al, 2005) therefore this split event should have occurred in Australasia coinciding with the origin of I. uriae proposed by Dietrich et al (2014). Probably Australasian Ixodes uriae passed the K-Pg boundary feeding on MB and Ixodes holocyclus or their ancestors, surpassed it as a parasite of Monotremata (eventually on early Australian marsupials or both).…”