The Jurassic King of Scotland

Last week, a [paper] was published that described a new fossil of a previously known mammaliaform from Scotland. This animal is called Wareolestes rex, meaning Ware’s brigand King and it’s from the middle Jurassic Period (specifically the Bathonian, 168 to 166 million years ago). Mammaliaforms were starting to diversify in the middle Jurassic, and were relatively small, so finding any fossils of them is important to our understanding of how they lived.

A reconstruction of Wareolestes by E. Panciroli.

The new specimen of Wareolestes is a lower jaw with teeth. This fossil was CT scanned and the details of the teeth were recreated with computer software. The authors found that the jaw had two molars preserved in place, and several teeth that were hiding in the bone, waiting to erupt.

Figure 4 from the paper showing the CT scan of the jaw. The large molars are already erupted, but several premolars and another molar are still in the jaw. The purple is the mandibular nerve. The scale is 1mm.

The original fossil of Wareolestes is an isolated molar, but similarities with the molars preserved in this new specimen show that the two specimens come from the same species. The shape of the teeth indicate that Wareolestes is a morgonucodontan (an early mammal relative).

The un-erupted teeth show that Wareolestes replaced their teeth once in life. Most mammals have a set of baby teeth (also called ‘Milk’ teeth) and a set of adult teeth. This happens for two main reasons: 1) our mouths grow over time, but teeth cannot grow once they are formed, so we grow adult teeth to fit adult-sized mouths. And 2) our teeth fit precisely together so that we can chew our food really well (this is called precise occlusion), by only replacing our teeth once, we ensure that our teeth will fit together appropriately.

A photo showing how the different cusps of the premolars (labeled P4, for premolar 4) and the molars (labeled M1 and M2 for molar 1 and 2) fit together. From P.D. Polly.

By comparison, other animals (like crocodiles, for example), do not have a final adult size – they grow continuously as they age. They also replace their teeth as many times as they need to ensure they always have teeth for grabbing prey, but they don’t chew like mammals do, so their teeth don’t have to fit together.

This new specimen shows that morganucodontans had a similar tooth replacement pattern as modern mammals, and are the most basal mammaliaforms that have it.

Off to the Field!

What’s ‘The Field’? It’s where paleontologists go to look for fossils. We call it Field Work, hence ‘going to the field’, and it can take place anywhere we travel to look for fossils. This year I was invited to join the crew from the Burpee Museum (in Illinois) to their field site in Hanksville, Utah.

Hanksville utah

I’ve been fossil hunting before, to the Petrified Forest of Arizona (Late Triassic sediments), and to the Gobi Desert of Mongolia (Cretaceous sediments). I’m really excited to be able to go to a new place (Utah) and a new time (Jurassic sediments) and hopefully interact with animals that died millions of years ago. I’m joining the crew for their last week in the field, so the goals of the trip are to hopefully find some new fossils, but mostly help them finish jacketing big fossil, loading them in to the cars, and packing up the gear they brought out there.

In this post, I want to share some of the equipment I’m taking with me. If you want to follow my journey live, follow me on twitter: @DrNeurosaurus

As an early career paleontologist, I have some field equipment, but not everything I need, so I’ll tell you what’s mine and what I’m borrowing from a friend. Firstly, housing. I’ll be sleeping in a tent (mine), with a sleeping pad (mine) and sleeping bag (borrowed).

My tent, with my fabulous dog model, Maia.

My tent, with my fabulous dog model, Maia.

sleeping bag pad

Sleeping bag and pad.

I’ll be bringing a first aid kit (mine), sun screen, and bug spray, because it’s important to be prepared. Spending a lot of time in the sun means dehydration, so to avoid that, I have an insulated 3 liter camelback, and a 1 liter Sigg bottle. I usually drink about 4 liters while I’m in the field and more back at camp.

water first aide

In terms of tools, I’m bringing my rock hammer, hand lens, 3 empty film containers (for small fossils), 1 small brush, a headlamp, a multitool, and a knife (all mine). The only camera I’m bringing is my cell phone.

tools

Tools from top left to bottom right: brush, carabiners, rock hammer, fire starter, awl, multitool, empty film containers, hand lens, and knife.

In addition, I have an assortment of clothes, 2 hats, a dinosaur bandana I’ve had since elementary school, boots, and a football (all mine). The sun stays up a long time in the summer, it’s fun to have something to do back at camp.

Next week, I’ll talk about the trip, the fossils we saw, the day to day around camp, and other fun things, so make sure to check back in!

all packed

I’m all packed! See you next week!