The fossil record of Australian dinosaurs in general, and theropods in particular, is extremely sparse. Here we describe an ulna from the Early Cretaceous Eumeralla Formation of Australia that shares unique autapomorphies with the South American theropod Megaraptor. We also present evidence for the spinosauroid affinities of Megaraptor. This ulna represents the first Australian non-avian theropod with unquestionable affinities to taxa from other Gondwanan landmasses, suggesting faunal interchange between eastern and western Gondwana during the Mid-Cretaceous. This evidence counters claims of Laurasian affinities for Early Cretaceous Australian dinosaur faunas, and for the existence of a geographical or climatic barrier isolating Australia from the other Gondwanan continents during this time. The temporal and geographical distribution of Megaraptor and the Eumeralla ulna is also inconsistent with traditional palaeogeographic models for the fragmentation of Gondwana, but compatible with several alternative models positing connections between South America and Antarctica in the Mid-Cretaceous.
Two different theropod pedal unguals from the Upper Cretaceous (Cenomanian) of Tafilalt, Morocco are described. One of them belongs to a slender kind of abelisauroid theropod. Comparison with other members of this group reveals that abelisauroid unguals show high morphological diversity in congruence with what is known on other parts of the skeleton. Another large-sized ungual resembles that described as "Spinosaurus B" by Stromer (1934), and is here referred with caution to Theropoda, although ignoring to which theropod lineage it belongs. Comparisons between northern (e.g., Sahara, Africa and Brazil) and southern (e.g., Patagonia) Gondwanan Cretaceous dinosaur faunas reveal some differences leading to the conclusion that Gondwanan faunas were not uniform across this supercontinent.
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