Eotephradactylus mcintireae

Eotephradactylus mcintireae life reconstruction（Image source：Brian Engh， CC BY-SA 4.0 ）

Age

Triassic（Norian）

209 Ma

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Taxonomy

Kingdom: Animalia

Phylum: Chordata

Class: Reptilia

Order: Pterosauria

Genus: Eotephradactylus

Species: Eotephradactylus mcintireae

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Morphological description

The preserved length of the mandible of Eotephradactylus mcintireae is approximately 4.1 cm. However, impressions in the surrounding matrix indicate that the complete mandible was at least 4.35 cm long. Based on comparisons with the closely related Eudimorphodon, the overall body size of E. mcintireae was likely comparable to that of a small gull.

Skull reconstruction of the closely related Seazzadactylus, showing similarly cusped teeth（Image source：Fabio Marco Dalla Vecchia， CC BY 4.0 ）

At least 24 alveoli are present in the mandible, with 12 containing erupted teeth. The mandible is narrowest at its midpoint and gradually expands toward the anterior end. The dentition is heterodont. The anterior teeth are slender, sharp, and caniniform, whereas the posterior teeth are broader and flattened. The first two teeth are too poorly preserved to determine whether they bore cusps. From the third to the eleventh tooth, each crown bears between one and seven prominent cusps. Grooves are present on both the anterior and posterior sides of the central cusp of these teeth, a feature that may represent an autapomorphy of this species. The twelfth tooth is heavily worn, obscuring the presence of cusps, but the grooves remain visible, suggesting that cusps were likely present.

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Etymology

The generic name Eotephradactylus is derived from the Greek Ἠώς (Eos, the dawn goddess), τέφρα (ash), and δάκτυλος (finger). "Eos" refers to its basal evolutionary position, "ash" reflects its discovery within volcanic ash deposits, and "finger" refers to the fourth digit that supports the pterosaur wing.

The species name honors Suzanne McIntire, who discovered the fossil while preparing a rock slab in 2013.

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Biological description

Eotephradactylus mcintireae was discovered in the Chinle Formation of Arizona, USA. It represents the earliest known pterosaur from North America and occupies a basal position within Pterosauria. The holotype consists of an incomplete left mandible (specimen number PEFO 53384). In addition, two isolated teeth and a wing phalanx have been referred to this species.

Skeletal reconstruction of Eotephradactylus mcintireae, with white and red indicating known elements（Image source：SlvrHwk， CC BY-SA 4.0 ）

Most of the teeth exhibit extensive wear, in some cases exposing the underlying dentin. This pattern suggests a diet that included hard-bodied prey, such as arthropods with robust exoskeletons or palaeonisciform fishes bearing hard ganoine scales. The latter are among the most common vertebrate fossils in the local strata, further supporting this dietary interpretation.

（Author: Bai Leng）

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Reference

Kligman, B. T., Whatley, R. L., Ramezani, J., Marsh, A. D., Lyson, T. R., Fitch, A. J., Parker, W. G., Behrensmeyer, A. K. (2025). Unusual bone bed reveals a vertebrate community with pterosaurs and turtles in equatorial Pangaea before the end-Triassic extinction. Proceedings of the National Academy of Sciences of the United States of America.

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