Dinosaur stomping ground in Scotland reveals thriving middle Jurassic ecosystem

During the Middle Jurassic Period, the Isle of Skye in Scotland was home to a thriving community of dinosaurs that stomped across the ancient coastline, according to a study published in the open-access journal PLOS ONE by Paige dePolo and Stephen Brusatte of the University of Edinburgh, Scotland and colleagues.

Dinosaurs on the Isle of Skye [Credit: Jon Hoad]

The Middle Jurassic Period is a time of major evolutionary diversification in many dinosaur groups, but dinosaur fossils from this time period are generally rare. The Isle of Skye in Scotland is an exception, yielding body and trace fossils of diverse Middle Jurassic ecosystems, serving as a valuable location for paleontological science as well as tourism.

(a) Field photograph, (b) outline drawing, and (c) contour map of a right manus/pes pair from BP1_Twy_01
highlighting the sediment deformation around each track [Credit: dePolo et al. 2020]

In this paper, dePolo and colleagues describe two recently discovered fossil sites preserving around 50 dinosaur footprints on ancient coastal mudflats. These include the first record on the Isle of Skye of a track type called Deltapodus, most likely created by a stegosaurian (plate-backed) dinosaur.

These are the oldest Deltapodus tracks known, and the first strong evidence that stegosaurian dinosaurs were part of the island's Middle Jurassic fauna. Additionally, three-toed footprints represent multiple sizes of early carnivorous theropods and a series of other large tracks are tentatively identified as some of the oldest evidence of large-bodied herbivorous ornithopod dinosaurs.

A field photograph and corresponding outline drawing showing the distinctive limestone cast infilling the impression
of BP1_30, the most clearly defined track in TA_1. The strong color contrast between the rock types serves
to accentuate the shape details of the track including the narrow, pointed digits and the elongated heel
[Credit: dePolo et al. 2020]

All tracks considered, these two sites expand the known diversity of what was apparently a thriving ecosystem of Middle Jurassic dinosaurs in Scotland, including at least one type of dinosaur (stegosaurs) not previously known from the region.

These findings reflect the importance of footprints as a source of information supplemental to body fossils. Furthermore, the authors stress the importance of revisiting previously explored sites; these new sites were found in an area that has long been popular for fossil prospecting, but the trackways were only recently revealed by storm activity.

BP3_13 is shown with both a field photo and a line drawing. It is the smallest track at BP3.
This narrow-toed track morphology–typical of Triassic and Early Jurassic tracks–is unique
with regard to all other tracks at BP1 and BP3 [Credit: dePolo et al. 2020]

Lead author dePolo says: "These new tracksites help us get a better sense of the variety of dinosaurs that lived near the coast of Skye during the Middle Jurassic than what we can glean from the island's body fossil record. In particular, Deltapodus tracks give good evidence that stegosaurs lived on Skye at this time."

Dr Steve Brusatte and Paige dePolo with fossil dinosaur tracks
on the Isle of Skye, Scotland [Credit: Steve Brusatte]

Author Brusatte adds: "These new tracksites give us a much clearer picture of the dinosaurs that lived in Scotland 170 million years ago. We knew there were giant long-necked sauropods and jeep-sized carnivores, but we can now add plate-backed stegosaurs to that roster, and maybe even primitive cousins of the duck-billed dinosaurs too. These discoveries are making Skye one of the best places in the world for understanding dinosaur evolution in the Middle Jurassic."

Source: Public Library of Science [March 11, 2020]



* This article was originally published here