Argentine fossil reshapes alvarezsauroid history, arguing for a Pangaean origin and stable body size
A new Argentine alvarezsauroid, Alnashetri cerropoliciensis, and two northern taxa prompt a major rewrite of alvarezsauroid evolution: phylogenetic analyses place Alnashetri outside the core alvarezsaurids, making South American taxa polyphyletic; biogeographic analyses imply a Pangaean origin with vicariance driving early diversification; and the early-branching position of Alnashetri argues against a universal miniaturization trend, showing body size evolving within a narrow range across the clade.