Dimorphodon was a species of pterosaur that lived during the early Jurassic Period about 195-190 million years ago. It measured over 3 feet long from its nose to the end of its long tail (which may or may not have terminated with a Rhamphorhynchus-like vane on the end), and it had a wingspan of 4.5 feet, making it roughly the size of a large hawk. It’s one of the most easily-recognizable pterosaurs due to the unique appearance of its deep semi-circular head, which measured 9 inches long, one-fourth of its overall body length. It’s because of its head’s unique and recognizable shape that Dimorphodon frequently appears within so many children’s books on prehistoric life alongside other recognizable pterosaur species like Rhamphorhynchus, Pteranodon, and Quetzalcoatlus.

Dimorphodon was one of the first pterosaurs to be classified. Its remains were discovered in Lyme Regis, Dorset, England in 1828 by Mary Anning, and it was officially named the following year by Rev. William Buckland – a man more famous for naming the meat-eating dinosaur Megalosaurus.

Since it was discovered in the early 1800s, several other specimens of Dimorphodon have been found, giving us a good impression of the creature’s anatomy. It’s been suggested that it was a poor flyer and was better suited to gliding rather than active flying. This was partly due to its short wingspan in proportion to body size, and also due to the structure of its feet. Unlike other pterosaurs which had a vestigial fifth toe, Dimorphodon’s fifth toe was greatly elongated, clawless, and oriented sideways. This likely supported a wide skin membrane spanning between the feet and the tail’s base, and would have given Dimorphodon a roughly four-winged appearance similar to the Cretaceous arboreal theropod Microraptor. This extra rear membrane would also have created additional surface area and provided extra lift in order to compensate for the moderate size of the main wings. In this regard, Dimorphodon could be interpreted as a Jurassic reptilian analog of a flying squirrel, swooping from tree to tree and making short-burst flights to catch insects in mid-air.

Although Dimorphodon is mostly associated with England, a partial skeleton was also uncovered in Mexico and was officially described in 1998. This suggests that it had a much wider distribution than previously thought. It’s therefore possible that other Dimorphodon skeletons are waiting to be discovered in other early Jurassic rock layers around the world in places like Massachusetts, Connecticut, New Jersey, Arizona, and southern China, but only time will tell if this is true.

In fact, partial remains of a pterosaur were found in 2009 in Massachusetts within rocks dated to the early Jurassic Period. The rocks where these specimens were found were “presumed” to be part of the Portland Formation (200-195 MYA), but it appears that the scientist studying the fossils made little attempt to verify this. The specimens consist of a single tooth and a series of wrist bones which have been ascribed to a non-pterodactyloid pterosaur. The specimens were highly weathered, making identification difficult, so it’s uncertain as to whether these belong to Dimorphodon or to another Early Jurassic pterosaur species. Based upon the size of the bones in question, it is estimated that this individual had a wingspan measuring 15.75 inches (40 cm), making this individual less than half the size of a fully-grown Dimorphodon – it might be a juvenile, or it simply might be a smaller species. The tooth was tentatively ascribed to the rhamphorhynchid sub-family Scaphognathinae, which includes such Late Jurassic genera as Scaphognathus and Harpactognathus. It’s not known if the tooth and the wing bones belonged to the same taxon. Both the tooth and wrist bones are currently housed within the collections of the Boston Museum of Science (collection ID code: MOS 2021.2-3) (McMenamin, Mark (2021). “Early Jurassic pterosaur from Massachusetts”. Academia Letters, article 3658 (October 2021). Pages 1-12. NOTE: This paper does not appear to have been peer-reviewed).

The drawing that you see below was made with No.2, No.3, and Crayola colored pencils on printer paper. NOTE: The original drawing which was posted here on November 9, 2022 has been removed because I got the shape of the wrist and hands wrong. Below is the updated version which was made on February 16, 2023.

Dimorphodon macronyx. © Jason R. Abdale (February 16, 2023).

Keep your pencils sharp, everyone.

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3 replies

  1. Interesting coloration for Dimorphodon. I think it would look right at home in the undergrowth. 🙂 I did not know there was a specimen from Mexico! That’s very exciting. Is it officially Dimorphodon or a close relative? Either way, it would be very cool to find more evidence of how far these animals were distributed.

    • The species found in England is named Dimorphodon macronyx, but the species found in Mexico is named Dimorphodon weintraubi. The Mexican specimen is housed within the Instituto Geológico de México (collection ID code: IGM 3494).

      Clark, James M.; Hopson, J. A.; Hernández R., R.; Fastovsky, D. E.; Montellano, M. (1998). “Foot posture in a primitive pterosaur”. Nature, 391 (6670). Pages 886–889.

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