Ctenochasma: the pterosaur with a changing tooth count

Ctenochasma was a Late Jurassic pterosaur with elongated jaws lined by many fine teeth. Fossils from Germany and France include individuals at different growth stages, allowing researchers to track changes that cannot be seen in a single specimen. In C. elegans, the reported tooth count rises from roughly 60 in a young individual to more than 400 in a large adult. The pterosaur catalogue places this striking anatomy alongside related forms while keeping feeding interpretations separate from direct fossil evidence.

Quick facts

Skulls that record growth

The long narrow jaws of Ctenochasma carry numerous slim teeth that project outward from the tooth-bearing margins. In the growth series attributed to C. elegans, small individuals have around 60 teeth, while large adults can exceed 400. New teeth were added toward the front as the jaws lengthened. A juvenile was therefore not simply a scaled-down adult with the same number of teeth.

This pattern matters for classification. Early workers named some differently sized or proportioned skulls as separate forms. Stéphane Jouve’s 2004 biometric and anatomical study showed that several supposed distinctions could reflect growth, while also noting unresolved material. Christopher Bennett’s 2007 review examined tooth form and variation across the genus and recognized more than one species. Later descriptions and revisions continue to refine those assignments; a small skull should not be named from size alone.

Localities and preservation

Important fossils come from the Solnhofen Lithographic Limestone of Bavaria and from Late Jurassic deposits in eastern France. Fine-grained lagoonal carbonates sometimes preserve delicate skull details and associated body parts. The French specimen described by Jouve preserved part of the braincase; its optic lobes occupied a lateral position but were proportionally smaller than those in birds. The anatomy is a direct observation, while comparisons with living animals require care.

Specimens differ in completeness and preparation. An isolated skull can reveal the jaw and tooth row but not the full wing or soft tissue. Localities and layers provide geological context; they do not show that every individual lived in identical conditions or shared the same exact diet.

How the tooth comb may have worked

The closely packed teeth formed a broad filtering or capture surface. Their geometry and the relatively low mechanical demands of the narrow jaws are compatible with handling small aquatic prey. Some studies compare the arrangement to a scoop or sieve rather than a modern baleen filter. Water movement through the teeth, the role of jaw opening and the prey size are functional interpretations, not preserved behaviour.

Coprolites containing aquatic remains have been used to discuss feeding by Late Jurassic pterosaurs, including ctenochasmatids. Such trace fossils can inform a broader ecological model, but they are not stomach contents tied to a named Ctenochasma skeleton. The genus should not be described as a proven filter feeder in exactly the same manner as Pterodaustro, whose lower jaw had a more specialized tooth apparatus.

What the fossils leave open

The jaw and tooth row are unusually informative, but they do not establish colour, social behaviour or a single feeding routine. Nor does an aquatic fossil setting alone prove that the animal lived in the water. The most secure picture is a flying pterosaur whose tooth count and skull proportions changed during growth, with likely access to small prey in shallow-water environments.