The Pterosaur Brain
In 1888, Newton published the first account of a pterosaur brain exposed in a skull from the Lias at Whitby, North Yorkshire. The skull fossil had to be excavated to reveal the exposed brain more fully. Before the work, a number of casts of the original were made and one such cast is shown below.
Perhapsicephalus purdoni, National Geographic Survey, Nottingham.
The brain fossil showed the main lobes clearly and the auditory and semicircular
canal structures were identified during excavation of the skull. The analysis
applied to the brain by Newton suggested that the brain of the pterosaur was in
many ways similar to the brain of a lizard, but in some respects it was
characteristically similar to the brain of birds. His conclusion was that
pterosaurs, birds and lizards evolved from common ancestors.
In 1941, Tilly Edinger, a German physiologist, examined two distinct pterodactyl fossils where the brain was exposed. Her findings were similar to those of Newton, but with the advantage of the intervening progress of science since the earlier investigation, Edinger was able to make a more defined conclusion about structure
Pterodactylus elegans, MCZ, No. 1505
The pterosaur fossils that Edinger worked with had been described by several
earlier and well respected German scientists, though the work that they did was
descriptive and comparative. This later work looked more closely at the
structures and extrapolated the knowledge to a general description of the
pterosaur brain for the first time.
Developments in the brains of pterosaurs show similarities with the development of the brain in birds. These changes are attributed to the requirements of flight, with a more developed optic lobe and a fissure (Vallecula Silvii) like that found in the fore brain of birds. At this point there is no evidence for the structure of the base of the pterosaur brain.
These are the two defining works on the nature of the pterosaur brain. With the advance in medical scanning techniques, the destructive analysis of pterosaur brains is a thing of the past. It is now possible in some cases, to examine the cranial cavity of a fossil by electronic means to develop an understanding of its brain anatomy. X-rays and Computer Tomography (CT) scans are both potentially effective ways of examining hidden details in fossils.
In 2002 Lawrence Witmer of Ohio University and his team conducted CT scans of the skulls of Rhamphorhynchus and Anhanguera. This allowed a 3D computer image to be generated, showing the skull internal structure and revealing the shape of the brain cavity.
The general conclusions from the studies so far is that pterosaurs had exceptionally well adapted brains for flight. The developments observed are essentially the same as those seen in birds, though some of the brain structures differ slightly in position and proximity to the eye sockets and spinal cord.
Newton E. T., 1888, On the skull, brain and auditory organ of a new species of Pterosaurian (Scaphognathus
purdoni) from the Upper Lias near Whitby, Yorkshire. Proceedings of the Royal Society, London. 43, pages 436–440.
Edinger T., 1941, The brain of Pterodactylus. American Journal of Science. 239, 665–682.