The first
mammal fossil ever found from the ‘time of dinosaurs’ was announced almost 200
years ago*. It was a small jaw just a couple of centimetres across, which
emerged from Middle Jurassic rocks in Oxfordshire, England. It was 150 years later
that the first such beast was found in Scotland. This week my colleagues and I described that Scottish specimen in detail for the first time, along with
stunning new material from the same species.
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| The most complete Mesozoic-aged mammal jaw found in Scotland so far, belonging to Borealestes serendipitus, a small insectivorous animal. |
The animal these
fossil bones belong to is delightfully called Borealestes serendipitus, the ‘northern rogue, found by chance’.
But it was not just luck, its founder Dr Michael Waldman tells me. Mike was
leading a group of school pupils on an outdoor skills trip to the Isle of Skye in the 1970s, and he knew from his
research that there were fossils in the area. He never imagined they would be
so spectacular or rare of course. Upon finding the first jaw, Mike brought the
tiny fossil, no bigger than a thumbnail, to his mentor and friend, Professor
Robert ‘Bob’ Savage at the University of Bristol. Together they returned to
Skye find more fossils from Scotland’s Jurassic heyday.
Since the
first publication on Borealestes in
1972, very little work has been done on it. Several jaws, a partial skeleton,
and some isolated teeth were found, but only two partial jaws were published,
and the descriptions were sparse. This new paper in the Journal of Vertebrate Paleontology is part of my ongoing research on the mammals of Jurassic
Scotland, begun while I was at National Museums Scotland (NMS) and the University of Edinburgh. I’m part of a team from NMS and the
Universities of Oxford and Birmingham who have been working on the Isle of Skye
since 2010, and finding yet more of this animal and the many creatures that
lived alongside it.
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| A new fossil jaw I found in 2016. Only the tooth tips were protruding from the rock. |
Our paper is
first and foremost anatomical, clarifying the identification (diagnosis) of Borealestes. In other words, how do you
recognise Borealestes if you find it?
This is predominantly based on the shape of the teeth. In 2003 a close relative,
Borealestes mussettae, was named from
isolated teeth from the English Jurassic-aged site of Kirtlington. Our new
paper sets out the differences between the two species, and re-evaluates all
previously known specimens in light of this new information (some were
previously misidentified).
The fossil specimens
are quite exceptional. They include the most complete Mesozoic mammal jaw found
so far in Scotland: a very long and slender dentary with delicate jaw hinge and
perfect insect-munching teeth. There is also a Borealestes specimen I found myself during fieldwork and so feel a
personal connection to, as well as the upper tooth row of a partial skeleton that
I’m currently completing work on with my colleagues (watch this space!)
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| The micro CT-scan of the jaw I found in 2016 revealed the rest of the bone hiding below the surface. Without computed tomography (CT) it is unlikely we could have studied this fossil intact. |
This publication
is the next in a series of papers on Borealestes.
In 2018 my colleagues and I described the ear bones of this Jurassic animal,
whereas this paper focuses on the jaw and dentition. With five jaws figured in
this publication, all from micro CT-scans, the upper molar row and incisors
known for the first time, and countless individual teeth re-evaluated, this
paper expands our understanding of this modest docodontan, and adds significantly
to the number of Mesozoic mammal specimens known from Scotland.
*The jaw
belonged to Phascolotherium. Other mammal jaws were found previous to this one,
but it was the first one recognised for its significance, and was announced (alongside
Megalosaurus) during the inaugural
address of the Geological Society of London by its first President, William
Buckland, in 1824.
References
Panciroli, E, Benson, R, and Luo,
Z-X. 2019. The mandible and dentition of Borealestes serendipitus (Docodonta) from the Middle Jurassic of Skye, Scotland. Journal of Vertebrate Paleontology. https://doi.org/10.1080/02724634.2019.1621884
