Cretaceous bird changed its diet

[Tim Williams <twilliams_alpha@hotmail.com>]

Naturwissenschaften, Online First

Short Communication

"Gastroliths in Yanornis: an indication of the earliest radical 
diet-switching and gizzard plasticity in the lineage leading to living 
birds?"
Zhonghe Zhou, Julia Clarke, Fucheng Zhang and Oliver Wings

Received: 17 July 2004  Accepted: 15 August 2004  Published online: 28 
September 2004

Abstract: Yanornis martini is an Early Cretaceous basal ornithurine bird. 
Its fish-eating diet was previously recognized from a discrete mass of 
disarticulated fish remains discovered in its abdominal region. A new 
complete and articulated specimen of Yanornis martini preserves abundant 
in-situ gastroliths such as have been associated with a herbivorous diet. We 
suggest that the occurrence of gastroliths in this specimen, fish remains in 
a second, and the lack of gastroliths in three others, is consistent with 
diet-switching in Yanornis martini. Incompatibility of the preserved data 
with explanations of the grit as an artifact of preservation or result of 
accidental ingestion is discussed. This discovery indicates the earliest 
presence of intermittent diet change (and associated gizzard plasticity) 
observed in extant birds seasonally and in response to changes in available 
food sources.

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