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Anhanguera santanaeFossil, Pterosaur
Dr. Lawrence Witmer - Ohio University College of Osteopathic Medicine
Dr. Sankar Chatterjee, Mr. Jonathan Franzosa, and Dr. Timothy Rowe
Anhanguera santanae
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American Museum of Natural History (AMNH 25555)

Image processing: DigiMorph Staff
Image processing: Mr. Ryan Ridgely
Publication Date: 30 Oct 2003


Neuroanatomy of flying reptiles and implications for flight, posture and behaviour

Lawrence M. Witmer, Sankar Chatterjee, Jonathan Franzosa & Timothy Rowe

Virtual endocast

Click thumbnail to see a 3 mb virtual endocast animation.

neck rotation

Click thumbnail to see a 1.3 mb animation of correct neck orientation.

ABSTRACT: Comparison of birds and pterosaurs, the two archosaurian flyers, sheds light on adaptation to an aerial lifestyle. The neurological basis of control holds particular interest in that flight demands on sensory integration, equilibrium, and muscular coordination are acute. Here we compare the brain and vestibular apparatus in two pterosaurs [Rhamphorhynchus muensteri and Anhanguera santanae] based on high-resolution computed tomographic (CT) scans from which we constructed digital endocasts. Although general neural organization resembles birds, pterosaurs had smaller brains relative to body mass than do birds. This difference probably has more to do with phylogeny than flight, in that birds evolved from nonavian theropods that had already established trends for greater encephalization. Orientation of the osseous labyrinth relative to the long axis of the skull was also different in these two species, suggesting very different head postures and reflecting differing behaviours. Their enlarged semicircular canals reflect a highly refined organ of equilibrium, which is concordant with pterosaurs being visually based, aerial predators. Their enormous cerebellar floccular lobes may suggest neural integration of extensive sensory information from the wing, further enhancing eye- and neck-based reflex mechanisms for stabilizing gaze.

see "Additional Imagery" for animations of the cranial endocast
About the Species

This specimen of Anhanguera santanae (AMNH 25555) was collected from the Lower Cretaceous Santana Formation of northeastern Brazil. It was made available to the University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Sankar Chatterjee of Texas Tech University. Funding for scanning was provided by Dr. Chatterjee. Funding for image processing was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe.

About this Specimen

The specimen was scanned by Richard Ketcham and Matthew Colbert on 26 May 1999 on the high-energy (P250D) subsystem along the coronal axis for a total of 595 slices. Scanning parameters were as follows: 420 kV, 1.8 mA, 1 brass filter, air wedge, 130% offset, integration time 64 ms, slice thickness = 0.5 mm, S.O.D. = 756 mm, 1000 views, 1 ray averaged per view, 1 view per sample, interslice spacing = 0.45 mm, field of reconstruction = 182 mm., reconstruction offset 500, reconstruction scale 900.

About the

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& Links

Click on the thumbnail for a 1 mb animation of the cranial endocast around the yaw axis.

Click on the thumbnail for a 1 mb animation of the cranial endocast around the roll axis.

Click on the thumbnail for a 1 mb animation of the cranial endocast around the pitch axis.


To cite this page: Dr. Lawrence Witmer, Dr. Sankar Chatterjee, Mr. Jonathan Franzosa, and Dr. Timothy Rowe, 2003, "Anhanguera santanae" (On-line), Digital Morphology. Accessed January 23, 2017 at http://digimorph.org/specimens/Anhanguera_santanae/.

©2002-20015 - UTCT/DigiMorph Funding by NSF