Earliest Gondwanan bird from the Cretaceous of southeastern Australia

Los Angeles County Natural History Museum, 900 Exposition Blvd, LosAngeles 90007, U.S.A.Our knowledge of Mesozoic bird evolution in Laurasia hasadvanced rapidly in recent years, fuelled by discoveries at richsites inChinaandSpain.TheavianGondwananrecord,however,remains sparse, and almost exclusively restricted to the LateCretaceous (Chiappe, 1996; Dalla Vecchia and Chiappe, 2002).In fact, only a handful of sites in eastern Australia have producedosteological remains dating from the Early Cretaceous. TheseAustralian localities have yielded a small number of isolatedelements; the Albian (Early Cretaceous) Toolebuc Formation inwestern Queensland yielded the tibiotarsus of an enantior-nithine, Nanantius eos, along with an additional tibiotarsus and avertebra (Molnar, 1986; Kurochkin and Molnar, 1997). Furtherfragmentary material representing Enantiornithes and possiblyIchthyornithiformes comes from the near-contemporaneous Gri-man Creek Formation of Lightning Ridge, New South Wales(Molnar, 1999). New avian material from the austral superconti-nent, therefore, has significant potential to shed light on theevolution of birds in Gondwana, and is critical for testing recenthypotheses on the evolution of crown clade Aves (Cracraft,2001). Here we describe an avian furcula from Aptian (EarlyCretaceous) sediments of coastal Victoria that represents theoldest osteological evidence for birds in Australia, and Gond-wana as a whole. Aside from a few small feather impressionsfound at Koonwarra, Victoria (Vickers-Rich, 1991), Mesozoicbirds have, until now, been unknown from southeastern Austra-lia. The new element shares several synapomorphies with Enan-tiornithes, and thus expands the geographic and temporal rangeof that clade. This would appear to strengthen the current viewthat Gondwanan avian assemblages were dominated in the EarlyCretaceous by more primitive forms (Molnar, 1986; Kurochkinand Molnar, 1997; Molnar, 1999), a picture at odds with currenthypotheses (e.g., that of Cracraft, 2001) placing the origin ofNeornithes in the southern supercontinent during this period.An avian furcula (first mentioned briefly by Rich et al., 1999;Museum Victoria P208183; Figs 1, 2) was discovered in 1997 atthe Aptian-aged (Early Cretaceous) Flat Rocks Locality in Vic-toria, Australia (38 39