Special interest

Bending over backwards to see the past

What killed the dinosaurs? Or more specifically, what killed these dinosaurs?

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Rearing up with their heads thrown back, mouth open and teeth bared, their final poses seem to bring them to life. But could this body position, called opisthotonic posture (or death pose), give us clues about how and why they died? That’s right, it’s time to play Dino-Detective!

Artist impression of what dinosaurs might have looked like

Opisthotonic death pose is very common in fossils, and so characteristic that you can generally spot it with ease in even the smallest of fossil exhibits. The head and tail are arched over the animal’s back, and the legs are often drawn into rigid-looking positions. But despite being known about and discussed for 150 years, people are still unsure why exactly dinosaurs so frequently adopt this petrified posture.

Many different reasons for the posture have been suggested, ranging from the very plausible to the downright bizarre.  For example, it’s been suggested that the pose it is actually a sleeping posture (does that look relaxed to you?!), or that the animal dived headfirst into mud and got stuck (it probably happened rarely, but is very unlikely in the case of large theropods or Camarasaurus, unless they were particularly stupid).

More comfortable/less horrifying sleeping posture

A more comfortable/less horrifying sleeping posture

Such suggestions are pretty easy to rule out, and aren’t talked about seriously. Rather, the big bone of contention revolves around whether the opisthotonic pose occurred before or after the dinosaur bit the dust.

Many people think that the pose is a post-mortem change, meaning that it happens after death. Different causes have been suggested, from water currents manipulating the body, to rigor mortis, to the ‘pull’ of drying tendons. However, Faux and Padian, writing in 2007 had a different idea. A background in veterinary medicine gave the authors a different perspective – rather than a change after death, perhaps the pose was a clinical sign of underlying pathology. Faux and Padian thought that these dinosaurs were still alive when they assumed the position, and the posture was a symptom of impaired brain function. It’s a symptom that medical professionals and many others will recognise…

Opisthotonos as a symptom of meningitis infection

Opisthotonos as a symptom of meningitis infection

Muscles are pretty trigger happy, and need inhibitory messages from the central nervous system to stop them contracting all the time. A problem in the brain or spinal cord can interfere with this inhibition. When that happens, the muscles all contract at once. Some are stronger than others (usually the extensor muscles) and pull the body into opisthotonic posture by force.

If Faux and Padian are right, it gives us clues about what might have killed these dinosaurs – severe head injuries, infections (e.g. tetanus and meningitis), poisoning, heat stroke, and lack of oxygen (e.g. drowning) can all cause opisthotonus and eventually death.

A dog with tetanus infection, which survived with intense veterinary nursing. Image credit.

A dog with tetanus infection. Without this intense veterinary care she would not have survived. Image credit.

 

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Foodie Friday

Foodie Friday – Lunch Autopsy

A biopsy of two strange lumps look like this under a microscope:

mysterymeat

What is that? Fat, skeletal muscle, nerves, epithelium, and bone? Some sort of strange, mixed tumour maybe?

Oh no, wait. My bad guys. It’s just lunch.

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Cases

Cyclops!

The title might give you one eye-dea about today’s topic – yup, we’re talking about cyclopia! Our fun-loving, larger-than-life, mono-ophthalmic monster buddies were first written about by the ancient Greeks, and later adopted by the Romans.

Luckily he has really bad depth perception

Lucky for those guys, he has really bad depth perception

The origins of the cyclops myth has been the subject of much discussion. Some suggest that the Greeks might have stumbled across the fossilised skulls of prehistoric dwarf elephants, and these creatures being extinct and unfamiliar to them, mistaken the schnozz-socket for a single giant eye.

Nasal cavity vs. actual eye hole

Nasal cavity vs. actual eye hole of an elephant skull

Others think that the Greeks had actually seen cyclopes in the flesh. A couple of rare developmental problems can result only one eye: in true cyclopia, only one eye is formed, whereas in synophtalmia, there may be two eyes which fuse.

Cyclopia

Itty bitty cyclops kitty

The Sonic Hedgehog and Pax6 genes are involved in properly dividing the embryonic brain (and extensions from it, such as the eyes) into two separate hemispheres.  There are several things that interfere with this process and so cause cyclopia, including certain drugs, viruses, genetic defects, and radiation. Alkaloid toxins in plants are also a culprit. In fact, ancient Greeks used some of these plants medicinally, and perhaps as a result, did see ‘real’ cyclopes…

Elephants and cyclopes also have another thing in common. Interestingly (or maybe morbidly), some cyclopes develop a tube-like structure instead of a nose, which is called a proboscis because it resembles a tiny trunk.

A cyclopic lamb with a proboscis, or trunk, above its eye

A cyclopic lamb with a proboscis, or trunk, above its eye

 

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Special interest

We need to talk about Kev-lar

Reading the newspaper this weekend, I was sad to learn that Stephanie Kwolek, inventor of Kevlar, died recently. Kevlar is best known for making body armour, but it’s also used in heat-protection gear, helicopter blades, bike tyres, ping pong bats, bowstrings, boat sails, tennis raquets, musical instruments, fire dancing props, frying pans, ropes, optical fibre cables, F1 racing cars, building construction, brake pads, rubber hoses, CERN particle physics experiments, wind and tidal turbines, and smartphones. Because it is such a ubiquitous product, I was surprised that one person was responsible for its invention, and that Kevlar has only been around since 1975.

We use Kevlar everyday; woven into gloves to protect our hands in post-mortems from over-enthusiastic scalpeling. (The idea of ‘bulletproof gloves’ is quite exciting when encountered for the first time, and therefore must always be accompanied with the disclaimer: “These gloves are glance-proof not stab-proof. They are designed for glancing blows ONLY. Please DO NOT stab yourself in the hand as an experiment.” Nevertheless, there’s always one…). You wouldn’t think Kevlar gloves would be so necessary (after all, how difficult is it to keep track of a blade?) but there are always a disconcertingly large number of slices out of the latex over-gloves by the end of a PM.

1965_A_StephanieKwolek_Detail_Vertical_630x815

So to Stephanie Kwolek, with our unscarred hands we salute you.

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Foodie Friday

Foodie Friday: Beefy Buns

It’s apparently football season, and McDonalds is getting into the spirit. But you know what they say; “one man’s football is another man’s offal”. Don’t you think this burger bun looks a little familiar?

foodie friday kidney

cow kidney vs. burger bun

Maybe they should’ve called it The Renaldo Burger…

(Images from Reddit.com and Quizlet.com. Can you guess the bonus pathology in this Foodie Friday post? No cheating, or you’ll get a red card and other miscellaneous football puns)

 

Edit 16/06/2014: Biologist on the Edge clued us in; the unusual colour of this kidney is due to amyloid accumulation, making it look yellow and pale and about as appetising as a certain fast food restaurant…

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Foodie Friday

Foodie Friday: Para-cakes!

Check out these parasite pancakes; pathology never looked so good!

Gotta catch 'em all!

Gotta catch ’em all!

 

These delicious and sometimes deadly delicacies were created by Nathan Shields over at Saipancakes. Head over for more inspired edibles!

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