Meeting Abstract

S9-1.6  Jan. 6  The evolution of cranial design and performance in lepidosaurians: consequences of skull bone reduction on feeding behavior. HERREL, A.*; SCHAERLAEKEN, V.; MEYERS, J.J.; METZGER, K.A.; ROSS, C.F.; University of Antwerp, Antwerp, Belgium; University of Antwerp, Antwerp, Belgium; U. Massachusetts, Amherst; Brown University, Providence; University of Chicago, Chicago anthony.herrel@ua.ac.be

The evolution of cranial design in lepidosaurians is characterized by a general trend towards the loss of distinct cranial elements. The loss of the lower temporal bar in squamates was associated with an increase in the mass of the jaw adductors resulting in higher bite forces and a more efficient feeding behaviour. Among squamates the supratemporal bar was reduced at least twice independently which induced a large degree of mobility into the skull. In Gekkotans this was accompanied by a reduction of the postorbital bar, resulting in a pronounced intra-cranial kinesis, a reduction in bite force and a decrease in feeding efficiency. Gekkotans, however exploited the intracranial mobility to increase jaw movement velocity allowing them to capture more evasive prey. In varanoids, the loss of the supratemporal bar also resulted in a decrease in bite force which was, however, compensated by a general increase in body size, specialized dentition and novel prey transport mechanism. The extreme degree of intracranial mobility that arose from the extensive reduction of dermal bones in ophidians and some pygopodids came at a cost of decreased bite performance and increased prey handling time. However, macrostomatan snakes and pygopodid geckos exploited their intracranial mobility to efficiently transport relatively large prey with minimal prey reduction prior to swallowing. Specialisations towards durophagy or herbivory in squamates arose independently in most groups and were accompanied by a general fortification of the cranial bones, increased jaw muscle mass and bite forces. Thus lepidosaurians appear to be a model system to investigate the consequences of morphological changes on performance and behavior.