Friday mystery object #347 answer

Last week I gave you these teeth to have a go at identifying:

20181018_130907-02.jpeg

It was a bit mean of me to only show the incisors, but I thought it would be way too easy otherwise and I thought that some of you would manage to get it. I was not wrong.

Despite the sparse information, James Bryant, Jennifer Macaire, Allen Hazen, sallie reynolds, Michelle Tabencki, Kaitlyn, Rémi and a tentative few others leaned towards one of the sabre-toothed cats, with most people opting for Smilodon. That is indeed what these teeth belonged to and if you want to be specific they’re from Smilodon fatalis Leidy, 1869.

742px-bc-018t-sabercat-tarpit-r2-lo

Reconstruction of Smilodon fatalis skull. Image by Bone Clones, 2000

The mystery specimen and I go way back as it’s the one in the Geology Department of Bristol University, where I did my undergraduate degree many years ago. It inspired me to do a project on Smilodon, which sent me around a variety of UK museums in search of specimens to measure.

That was the start of my behind-the-scenes experience in museums and I met some fantastic people, including the legendary Andy Currant at the NHM, London, who was so helpful, knowledgeable and welcoming that it left an indelible mark on my attitude to collections access and curation.

I still have a soft spot for Smilodon and of all the palaeontological questions that I’d love to see resolved it’s how their bizarre canines worked. I never considered the “Akersten canine-shear-bite” [opens as pdf] as being biomechanically plausible, not least because it requires the jaws to close during the bite, which would in turn require these incisors to penetrate the skin and some (or all) of the underlying tissue of the prey.

While these incisors are robust, they’re just not the right kind of shape for that type of action as the straight and fairly level row would dissipate force quite evenly during a bite, rather than allowing the high point loads well suited to penetration.

There are other, more plausible methods proposed (e.g. Brown, 2014), but without seeing Smilodon in action it’s one of those mysteries that may never be satisfactorily resolved. And who wouldn’t want to see something as terrifying as a gigantic, sabre-toothed feline in action?

Smilodon californicus and Canis dirus fight over a Mammuthus columbi carcass in the La Brea Tar Pits. By Robert Bruce Horsfall, 1913

Smilodon californicus and Canis dirus fight over a Mammuthus columbi carcass in the La Brea Tar Pits. By Robert Bruce Horsfall, 1913

 

Friday mystery object #346 answer

Last week I gave you this funky fossil from the National Museum of Ireland to have a go at identifying:

20181208_161002-01.jpeg

Everyone in the comments immediately recognised that this is the fossil of something that flies, thanks to the slender bones. The general consensus from the outset was that it was Archaeopteryx, but I wonder how much of that is because this specimen is preserved in the same Middle Jurassic lithographic limestone from Solnhofen that preserves the first bird?

The Berlin Archaeopteryx

The Berlin Archaeopteryx

However, Allen Hazen noticed the long slender finger that marks the mystery object as something different, when he correctly suggested that it was a pterosaur, winning over palfreyman1414 and sallie reynolds. On Twitter, @Robertgagliano1 went one better and got the correct genus when he suggested Germanodactylus.

This is indeed a fossil of Germanodactylus cristatus (Wiman, 1925). These small Jurassic pterosaurs were about the size of a raven and it is thought that they may have fed on marine crustaceans and molluscs, based on their fairly robust teeth.

This particular specimen is currently on display in our Jurassic Skies exhibition (that I talked about a fortnight ago), as it helps represent the successful group of flying reptiles that were already in the air 150 million years ago, when feathered dinosaurs first took to the skies.

In an unexpected twist, research was published just a week after we opened the exhibition, describing the first evidence for feathers in pterosaurs. This was unexpected, although fur-like filaments had already been recognised in the group. This means it’s possible that feathers originated in a common ancestor of dinosaurs and pterosaurs – which may have even included the group that is today represented by the crocodiles.

This means it’s possible that the ancestors of crocodiles would have been feathered and modern crocodiles have lost this covering, possibly thanks to their specialisation for living in water. I find it quite interesting that a reticence to add feathers to representations of dinosaurs (in things like Jurassic Park) has been influenced in part by the scaly skin of modern crocodiles (the nearest living relatives to dinosaurs that are not birds), but now we find out that crocodiles may have had feathers and lost them, making prehistory a much more fuzzy place than we ever dreamed!

Friday mystery object #345 answer

Last week I gave you this squee squamate to have a go at identifying:

As usual the comments were insightful and bang on target, with a correct identification by Chris, jennifermacaire, sallie reynolds and Allen Hazen. In the comments there was even a link to a very useful paper provided by jennifermacaire and a mention of the value of the tail-tip shape as a way of distinguishing between species of flying gecko.

Unfortunately the end of this specimen’s tail was hidden behind a label, so it wasn’t visible in any photos, but if it was it would show that this is a Common Flying Gecko Ptychozoon kuhli Stejneger, 1902. Distinctive tail-tips aside, the comments also picked up on some very interesting points about gliding replies. As Allen Hazen mentions:

… So gliding with a patagium along the side of the body (not supported by the arms and legs as it is in typical mammalian gliders) has evolved at least FOUR times in reptiles (reptilia sensu very lato): these guys, Draco, Kueneosaurus, and another fossil form I can’t remember the name of. …

Which is both interesting and pertinent to the main reason I picked this object, as it’s one of the specimens I selected for the temporary exhibition Jurassic Skies we just opened at the National Museum of Ireland at our Collins Barracks site, which is about the origins of flight in dinosaurs (i.e. birds).

This slideshow requires JavaScript.

Gliding lizards don’t have much to do with the origin of birds directly, but the high frequency with which they seem to pop up is a good indicator that there’s a clear benefit to being at least partially air-worthy.

Escaping predators, reaching inaccessible food and exploiting otherwise hard-to-reach habitats can all play a role in tempting animals into the air. The interesting thing that I’ve realised from doing this exhibition is that we’re currently in a bit of a dull patch when it comes to flying critters.

In the Jurassic the pterosaurs dominated the skies, with birds arising and finding a niche despite being newcomers to the aerial scene. By the Cretaceous both birds and pterosaurs were very diverse, with giant Quetzalocoatlus pterosaurs the size of a small plane and toothed and toothless birds living in a variety of habitats.

The K-T boundary mass extinction seems to have wiped out a huge amount of vertebrate diversity in the skies and despite the huge number of bird species alive today, the diversity of forms seems lower than it has in the past.

If you happen to be in Dublin before 24th March 2019 I suggest popping over to the Collins Barracks museum site to take a look at the exhibition. It’s free and it offers a chance to see some of our specimens that have never been on display before, plus a rather lovely new model of Archaeopteryx that we commissioned for the show.20181211_162925

Friday mystery object #344 answer

Last week I gave you this impressive insect to have a go at identifying:

mystery344.jpeg

No scale for this, but it’s probably safe to say it’s bigger than you’d be comfortable with.

By not giving the scale I was being a bit mean by holding back a useful clue. This fly (as recognised by palfreyman1414, Richard Blackmore and joe vans) is around 45mm long, making it one of the biggest of its kind – its kind being one of the Asilidae or robber flies.

The species is from Australia and it’s called the Giant Yellow Robber Fly Blepharotes coriarius (Wiedemann, 1830). They’re active hunters that prey on other insects, grabbing them in flight and carrying them off to a perch where they suck out their victim’s internal organs. Nice.

Apologies for the short answer this week – I’m just in the process of installing an exhibition and this specimen is one that is going on display to represent the Diptera. Hopefully I’ll be able to share some images of what I’ve been working on next week.