Dearc: Beast of the Week

 This week we'll be checking out a newly described pterosaur.  Make way for Dearc sciathanach!

Dearc (pronounced like jark)was a pterosaur that lived in what is now Scotland during the middle Jurassic period, about 166 million years ago.  The one skeleton found would have had a wingspan of about 8 feet (2.5 meters), but it's possible this taxa could have grown large in life, with wingspans of over 9 feet. (3 meters)  The genus and species name translate from Gaelic to "Flying Lizard". Like many of its relatives, Dearc, was almost certainly a meat-eater when alive, possibly preying on fish.

Watercolor life reconstruction of Dearc by Christopher DiPiazza.

Dearc is special for a few reasons.  It was a member of what is referred to as the rhamphorhynchoid group of pterosaurs, which flourished during the Triassic and Jurassic, but appeared to have gone extinct by the Cretaceous periods.  They are identified by having long, pointed teeth, proportionally short hind legs, and long narrow tails.  Dimorphodon is another example of a rhamphorhynchoid.  The other pattern about this group of pterosaurs is that they are overall smaller when compared to their cousins, the pterodactyloid pterosaurs. (like Pteranodon or Quetzalcoatlus) With this in mind, Dearc is particularly large for a rhamphorhynchoid, with a wingspan that was over eight feet or more given that  the individual specimen unearthed was still growing when it died!  

It is the most well-preserved pterosaur specimen to ever be discovered in the United Kingdom, known from an almost complete skull (missing the top of the head and top tip of the jaw, and almost the entire body.  Only the legs, some of the wing bones, and the tip of the tail are really missing.  This is amazing since pterosaurs, having such delicate bones, are not usually fossilized at all unless in really specific conditions, and when they are, they're usually either highly fragmentary or totally flattened to the point their bones are almost in two dimensions when found. Dearc, on the other hand's skull was so well preserved, that paleontologists were able to scan the inside of it and learn what the shape of its brain and inner ear cavities looked like!  Their findings suggest Dearc had a proportionally tiny brain, except for the optic lobes which were huge. This means Dearc would have had sharp eyesight when alive which makes sense for flying and searching for prey from the air.

Fossil of Dearc. photo from the paper describing the taxa by Natalia Jagielska. (listed below)

Dearc's environment would have been much warmer tan it is in Scotland today, and consisted of a series of small islands surrounded by shallow tidal seas.  Dearc may have used its sharp eyesight to hunt for food while flying in the air, possibly even plucking small fish or other animals from the surface of the water with its long, low skull, and extremely long, interlocking teeth.  I can also imagine it being an opportunistic feeder, going after any marine life stranded on sand bars during low tide.  Unfortunately not much is known about any of Dearc's neighbors since the fossil record of its time is still pretty scarce.  That being said dinosaur tracks, including those from stegosaurs, ornithopods, and theropods, were discovered near Dearc's skeleton from the same time, so it was definitely sharing space with large dinosaurs! 

References

dePolo, Paige E.; Brusatte, Stephen L.; Challands, Thomas J.; Foffa, Davide; Wilkinson, Mark; Clark, Neil D. L.; Hoad, Jon; Pereira, Paulo Victor Luiz Gomes da Costa; Ross, Dugald A.; Wade, Thomas J. (2020-03-11). Fiorillo, Anthony R. (ed.). "Novel track morphotypes from new tracksites indicate increased Middle Jurassic dinosaur diversity on the Isle of Skye, Scotland"

Natalia Jagielska; Michael O’Sullivan; Gregory F. Funston; et al. (February 2022). "A skeleton from the Middle Jurassic of Scotland illuminates an earlier origin of large pterosaurs". Current Biology. 32: 1–8.