A reassessment of the purported venom delivery system of the bird-like raptor Sinornithosaurus

GIANECHINI, F. A.; AGNOLIN, F.L.; EZCURRA, M. D.

PALAEONTOLOGISCHE ZEITSCHRIFT

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2011 vol. 85

0031-0220

Gong and colleagues recently described unusualtraits in the dromaeosaurid Sinornithosaurus that wereinterpreted as the first evidence of a venomous dinosaur.This interpretation was based on extremely elongatedmaxillary teeth, morphologically similar to those present inpoisonous snakes; labial grooves on maxillary and dentarytooth crowns; and an additional ornamented depression inthe lateral surface of the maxillary bone (subfenestralfossa). A reappraisal of each of these morphological traitsis provided here in light of comparisons with other theropoddinosaurs and previous discussions for inferring poisonouscapabilities in fossil taxa. We fail to recognizeunambiguous evidence supporting the presence of a venomdelivery system in Sinornithosaurus. For example, theextremely elongated teeth seem to be a taphonomic artifactdue to the displacement of teeth outside the alveoli; thelabial grooves are present in a wide variety of theropods;and no strong evidence for the lodging of a venomousgland is recognized. In contrast, the cranial and dentalanatomy of Sinornithosaurus is congruent with that ofother dromaeosaurids. The weak support for a venomousSinornithosaurus renders unlikely the ecological modelproposed by Gong and colleagues for this predatorydinosaur.