I've been lucky enough to see my first scientific paper come out this year (first of many I hope!) with my wonderful colleagues, Stig Walsh (National Museum of Scotland) and Roger Benson (Oxford). We describe a lower jaw found in the last couple of years during our ongoing palaeontological fieldwork on the Isle of Skye, Scotland. It is from the Kilmaluag Formation: which is Bathonian (Middle Jurassic) in age. This lower jaw, or dentary, is from a relatively large Mesozoic mammal living around the lagoons of Jurassic Skye. What’s more, it retains replacement teeth inside the jaw. This is the first evidence for mammalian milk-production in the Scottish fossil record.
|The surface of the jaw was somewhat abraded by wave action, but microCT scanning revealed exceptional details (see below). The fossil is now part of the collection at the National Museum of Scotland: NMS G.2016.34.1|
We identified the jaw as belonging to Wareolestes rex. Scampering between the copious turtles and crocodiles near the water’s edge, or perhaps living further inland and being washed by river into one of these lagoons upon death, Wareolestes is one of the many mammals that lived alongside their infamous dinosaurian cousins at this time in Earth's history.
|The holotype of Wareolestes rex, NHMUK PV M36525.|
Wareolestes rex means 'Ware's brigand king', and was named in 1978 by Eric Freeman as one of several species recovered from productive fossil mammal beds in Oxfordshire. Productive is a relative term for mammal palaeontologists. We aren’t talking about whole skeletons, or even skulls. We’re talking teeth – lots and lots of them. Sifting through them, many new species of mammal were discovered and named. You can flick through hundreds of them in the collections at Oxford Museum of Natural History and the London Natural History Museum, each mounted on a pinhead and placed carefully in its own miniature test tube.
This Scottish jaw is not only the most intact fossil of this species yet found, but only the third species of Mesozoic mammal described from Scotland. (There are others: watch this space, as I'll be publishing on them in the near future).
|The jaw was microCT scanned, revealing beautiful detail. This is a lingual view. Inside, several unerupted adult teeth tell us this animal was a sub-adult, and that it had the modern pattern of mammal tooth replacement.|
When we microCT-scanned it, we discovered the replacement teeth were still sitting inside the jaw. They are all more or less level, suggesting the teeth were replaced at approximately the same time. Sadly, the wave-damage means we can’t be more definitive about the sequence of replacement, but hopefully future finds will confirm this.
|This is my palaeoartistic reconstruction - check out tomorrow's blog for more on how it was made.|
|My 3D print out of Wareolestes rex.|
Freeman EF. 1979 A Middle Jurassic mammal bed from Oxfordshire. Palaeontology, 22, 135-166.
Panciroli E., Benson RBJ., and Walsh S. 2017 The dentary of Wareolestes rex (Megazostrodontidae): a new specimen from Scotland and implications for morganucodontan tooth replacement. doi: 10.1002/spp2.1079