Comment on “A Southern Tyrant Reptile”

Abstract

Benson et al . (Brevia, 26 March 2010, p. 1613) reported on an Australian tyrannosauroid, represented by a pubis from the late Early Cretaceous of Victoria. However, our examination of this specimen reveals that the critical character used for this referral is not present. We contend that the bone likely belongs to a currently recognized group of Australian theropod or another group not currently known.

Response to Comment on “A Southern Tyrant Reptile”

“…Herne et al (2), however, argue that the pubic tubercle is broken and cannot provide evidence for tyrannosauroid affinities. We described the base of the broken pubic tubercle as indicative of an anterolaterally curving morphology, similar to that of tyrannosaurids (3) [ figure 1D in (1)].…”

“…This is similar to the ratio of 6.6 in NMV P186046, which is narrow compared with~2.4 in non-coelurosaurian neotetanurans (allosauroids) with boots of comparable size (6). Herne et al (2) suggest that NMV P186046 is incomplete distally and may have been wide before breakage. However, to be proportionally broad, as in allosauroids, NMV P186046 must have been 58 mm wide, almost three times the preserved width of 21 mm.…”

“…1A). Herne et al (2) state that this depression is smooth, unlike in tyrannosaurids in which it is rugose [ figure 1D in (1)] (3). However, rugosity is present proximally (Fig.…”

“…Many "endemic" clades are now known from both hemispheres [e.g., "Gondwanan" abelisauroids (11) in Europe and "Laurasian" dromaeosaurids in South America (e.g., 12)]. Third, of the Australian theropod clades cited by Herne et al (2), only the carcharodontosaurian Australovenator is represented by substantially complete remains (13). These are of similar age to NMV P186046 and indicate that it is the sister taxon of Fukuiraptor from Japan (14).…”

“…Finally, Herne et al (2) state that because a long history of collecting has not uncovered any Gondwanan tyrannosauroids, their presence is unlikely. There are three problems with this claim.…”