Dearc sgiathanach is a long-tailed pterosaur from Middle Jurassic rocks on the Isle of Skye, Scotland. Its three-dimensionally preserved skeleton includes much of the skull and limbs, making it an unusually informative fossil for this interval. The individual was still growing. The original study estimated a wingspan greater than 2.5 metres, while the incomplete wing elements leave room for uncertainty in that reconstruction. The pterosaur catalogue lists the estimate alongside what the specimen actually preserves.
Quick facts
| Name | Dearc sgiathanach Jagielska et al., 2022 |
|---|---|
| Group | Pterosauria, Rhamphorhynchidae; Angustinaripterini |
| Age | Middle Jurassic, Bathonian |
| Place | Kilmaluag Formation, Isle of Skye, Scotland |
| Holotype | NMS G.2021.6.1–4, partial articulated skeleton |
| Growth | Juvenile to subadult; still growing |
| Wingspan | Estimated above 2.5 m in the original study |
What can the fossils tell us?
Amelia Penny noticed the exposed jaw; fieldwork recovered the block before coastal erosion could destroy it.
The preserved wing bone records growth lines, but the exact age at death and adult size are not known.
Several wing phalanges are fragmentary or incomplete, so the result relies on comparison and statistical models.
Discovery on a tidal shore
Amelia Penny noticed a pterosaur jaw weathering from a limestone slab on the Isle of Skye in 2017. A team returned to collect the block before tides and erosion could break it apart. Natalia Jagielska and colleagues described the fossil in 2022 as Dearc sgiathanach. The Gaelic name refers both to a winged reptile and to Skye.
The holotype, NMS G.2021.6.1–4, is held by National Museums Scotland. It preserves a nearly complete skull and lower jaw, vertebrae, shoulder and pelvic elements, and portions of the limbs. Some bones remain articulated, while others are damaged or incomplete. It is a single individual rather than a composite skeleton.
Growth and an unusually large span
Bone histology of a wing phalanx shows primary fibrolamellar tissue and two prominent lines of arrested growth. Together with incomplete fusion in parts of the skeleton, this indicates a young animal that was still actively growing. The evidence does not provide a precise calendar age or the final size it would have reached.
The original description estimated a wingspan greater than 2.5 metres, making this an especially large Jurassic pterosaur represented by a well-preserved skeleton. The estimate was calculated from preserved limb measurements and predictor relationships for better-sampled long-tailed pterosaurs. Some wing phalanges are fragmentary, and different choices of model can produce different values. The number is a scientific estimate, not a direct measurement of an intact outstretched wing.
Skull anatomy and evolutionary relationships
The skull preserves a long toothed rostrum and several features used to distinguish the genus, including details of the palate and braincase. Its phylogenetic analysis placed Dearc among rhamphorhynchines, close to the Chinese forms Angustinaripterus and Sericipterus in the newly named Angustinaripterini. Family trees depend on the characters and other taxa included, but this result connects the Skye animal to a wider Jurassic lineage.
These traits distinguish it from earlier Scottish pterosaur finds that are fragmentary or from different formations. The Bathonian Kilmaluag Formation represents a varied coastal and lagoonal setting. The geology supplies context, but it does not reveal exactly where this individual fed or how it behaved.
What remains reconstruction
The fossil does not preserve a complete wing membrane, skin colour or soft-tissue outline. The full wing shape and posture in an illustration must be restored from bones and comparison. Fish or other small animals are plausible prey for a toothed pterosaur, but there are no gut contents in the holotype to confirm a specific diet.
Dearc changed expectations because a growing, long-tailed pterosaur from the Middle Jurassic was already large. It does not establish a precise adult maximum or make every visual detail certain. The skeleton remains a rare, strong data point for a period with a sparse pterosaur record.
Frequently asked questions
Where was Dearc found?
It was collected from the Middle Jurassic Kilmaluag Formation on the Isle of Skye, Scotland.
Was the specimen an adult?
No. Histology and incomplete skeletal fusion indicate a juvenile to subadult individual that was still growing.
How wide were its wings?
The original study estimated a wingspan greater than 2.5 metres, using incomplete bones and comparative models.
What did Dearc eat?
Its teeth make small animal prey plausible, but the specimen preserves no direct gut contents or identified prey.