Xenon's Seventh Circle

Day 28: For the final day, it's Amphicoelias fragillimus, the dinosaur that may or may not have existed. Back in the 19th century, two Americans, Edward Drinker Cope and Othniel Charles Marsh, were embroiled in a decidedly unfriendly race to discover the most dinosaur bones. They had spies in each other's camps, and were at pains to ridicule each other's mistakes at every opportunity - and, given that their rivalry caused them to rush the business of finding and naming new dinosaurs, there were quite a few mistakes. In the midst of all of this, Edward Drinker Cope found a vertebra which, if his measurements were correct, would have belonged to an absolutely massive dinosaur, far bigger than anything found to this day. Due to the close scrutiny from Marsh, we can be sure that he didn't make up his discovery. That would have been professional suicide. It has been suggested, however, that during the hurry to write up his notes, he may have misplaced a digit, accidentally inflating the size of his find.

Argentinosaurus huinculensis is generally held to be the biggest dinosaur, reaching around thirty-five metres in length. Amphicoelias fragillimus (the second name refers to the very fragile condition of the fossil) is estimated to have been some fifty-eight metres long. Whether it could even have walked is a reasonable question! Nobody doubted Cope though. He had too much to lose to lie. Unfortunately, due to the sheer volume of fossils discovered in his race with Marsh, many remained in boxes for later examination, often for a long time - and Amphicoelias was fragile. By the time anybody went looking for it, it had disappeared, either because it had fallen apart, or because - due perhaps to an error in Cope's notation - it was overlooked, since it wasn't nearly as big as expected. Unless more is found (and people do keep looking - it's something of a Holy Grail, at least amongst those who still believe), we shall probably never know.

So there you have it - the maybe dinosaur. If it did live, it would have been in Colorado in the late Jurassic (some 150 million years ago), and would have been an herbivorous sauropod (think very, very big Diplodocus). Did it? Didn't it? Probably not, in all honesty, but it's a nice thought!

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To finish, two new dinosaurs, both announced this month: Bajadasaurus pronuspinax and Moros intrepidus. The first is another sauropod, with some rather fetching spikes. Bajadasaurus lived in the early Cretaceous (c. 140 million years ago), in Argentina, and is quite rare amongst sauropods in that it has been found with its skull mostly intact. Sauropods were basically giant, digesting machines. All the important stuff went on in the body, and the head was a small thing, with fairly rubbish teeth, which grabbed stuff and swallowed it. Consequently they don't tend to last well, and most sauropods are found headless.

Moros intrepidus was a tyrannosaur, from the later Cretaceous (c. 96 million years ago), in Utah. The most famous tyrannosaur is, of course, Tyrannosaurus rex, a giant predator from the end of the Age of Dinosaurs. Not all tyrannosaurs were so big, particularly earlier on in their development, and Moros was a tiddler in comparison to its later relatives. It would have been very fast though, and whilst smaller than later tyrannosaurs, it was bigger than its predecessors. A step on the road to T. rex then perhaps. And, in the meantime, plenty big enough to bite your head off!

Day 26: The first dinosaur known to science, Megalosaurus bucklandii is named for William Buckland, a churchman who devoted his spare time to studying natural history and geology. In the frontier of palaeontology, he was one of the very first to try to make sense of the giant bones that were being discovered, with the result that his idea of what Megalosaurus looked like bares little resemblance to the modern view! He saw it as a scaled-up version of extant reptiles, walking on all fours, with a sprawling gait. We now know it to have been a biped, with a similar basic form to the other carnivorous theropods.

From the mid-Jurassic (c. 165 million years ago), it lived in Europe, with the best specimens found in Oxfordshire. The very earliest examples were found in the 17th century, long before anybody had any idea what they were, and consequently the first recorded name assigned to a dinosaur bone, part of a Megalosaurus femur, was somewhat infamously Scrotum humanum, as it looked a bit like a petrified scrotum. Technically speaking, since zoology always recognises the oldest name as the official one, that is what Megalosaurus ought to be known as today, but the rules have been politely ignored!

Scrotum humanum. Not the world's best ever dinosaur name. Still, you can see their point.

Day 24: Zuul crurivastator is an ankylosaur, found in superb condition (well - for a 75 million year old fossil, anyway) in Montana just a couple of years ago. It gets the first part of its name in honour of Ghostbusters, and the second bit, crurivastator, effectively means "destroyer of shins", as it had a whacking great club on the end of its tail. Roughly six metres long, it would have been a heavily armoured herbivore, covered in spikes and bumps, and very much not the sort of thing that you want to piss off.

There's a handy (silent) little YouTube video here that shows some of the bones, including the surprisingly cheerful skull; a life restoration; and a size comparison with an African elephant, just in case you should be needing such a thing. One minute twenty-five seconds.

Day 22: Therizinosaurus cheloniformis! The exclamation mark is wholly warranted, trust me. If ever there were proof that Evolution likes its whisky neat, it's Therizinosaurus. Around twice as tall as our waving, size-guide man, and a good nine metres long, pot-bellied, covered in feathers (or feather-like integument), and with a metre-long claw on each finger, Therizinosaurus looked a bit like something out of Pan's Labyrinth. It was a herbivore though (probably!), and presumably used the claws to slash up vegetation rather than other dinosaurs. It was a theropod, a group of bipedal dinosaurs that were overwhelmingly carnivorous, so it may have started out that way and evolved. Sort of like a panda then, both in terms of diet and general absurdity.

From Mongolia in the late Cretaceous (c. 70 million years ago), Therizinosaurus was something of a mystery for years, as people kept finding odd bits like claws and hands, and wondering what the bloody hell they'd unearthed. Palaeontology is always a bit like putting together a jigsaw without the picture on the front of the box, though as you learn more, and find more, it is possible to use comparative anatomy and educated guesswork to help out. And then sometimes you find a disassociated bit of Therizinosaurus in the desert, and are left boggling for half a century.

Therizinosaurus. What happens when Evolution has a night on the tiles.

Day 20: When I was a kid, I had a little plastic toy Polacanthus foxii. It was one of my favourites. The current models don't look much like mine did back then! One of the great things about science is how it moves forward, but it doesn't do to get too attached to a particular image of a dinosaur, because even ten years can see them completely reimagined, let alone thirty-plus years.

An ankylosaur, Polacanthus was originally found on the Isle of Wight (further specimens have since been found elsewhere in Europe). It dates from the early Cretaceous period, around 125 million years ago, and although not many specimens are known, we do know that it was armour-plated, as were all the ankylosaurs, and had some spikes as well for good measure. It would have been an herbivorous quadruped, probably about five metres long, slow-moving, and very well defended against predators. It probably wasn't invulnerable, but it can't have made for easy eating!

Day 18: Psittacosaurus is adorable. Not sure it needs a lot more saying about it than that! The name means "parrot lizard", although it didn't look especially parroty, if we're honest. From the early Cretaceous (around 125 million years ago, in Asia), it was quite small, and decidedly beaky, although its "beak" contained teeth. One interesting thing about Psittacosaurus is how much variation there is within the genus. There are currently some ten species known, all exhibiting an assortment of adaptations, presumably to suit particular locations and situations. Lots of specimens have been recovered, some in such good condition that it's been possible to analyse them at the microscopic level, and see from the melanosomes roughly what colour Psittacosaurus would have been.

Adding to its cuteness (or oddness, depending on your point of view) is the big tuft of bristly projections on its nether quarters, which makes it look a bit like it had a punk hairstyle, but on the base of its tail. Presumably this was used for display, or possibly to scare off predators. Or both.

Picture here.

Day 16: I love Compsognathus longipes. Long thought to be the smallest dinosaur, it's since been roundly beaten to that title, but nonetheless, it was a little creature that scurried around Europe in the late Jurassic, some 150 million years ago. It's actually been found with stomach contents intact, so we know that (possibly amongst other things) it ate small, fast-moving lizards. It would have been fast, then, and possibly feathered to some extent. (No specimens have been found with traces of feathers, but several of its relatives are known to have had coats of what have come to be known as "proto-feathers", like feathery forerunners.) Again, it would be nice to have a look, please and thank you.

Day 14: Knowledge and discovery are a complicated business. When I was a kid, to underline the fact that the flying reptiles (Pterodactylus antiquus, etc), and the marine reptiles (Plesiosaurus dolichodeirus, etc) are not dinosaurs, there used to be a mantra: Dinosaurs walk. They don't fly, and they don't swim. Then we found out that actually yes, they did (and do!) fly. And then we found out that they swam as well. Spinosaurus aegyptiacus is the most famous swimming dinosaur, although its British cousin Baryonyx has been known about for longer, but wasn't properly associated with a semi-aquatic lifestyle until later. Spinosaurus aegypticus (Egypt, c. 100 million years ago) was an absolutely massive creature with a sail on its back, and although a theropod (traditionally bipedal), it may have preferred a semi-quadrupedal gait on land, with its mass and balance better suited for the water. It doesn't seem to have been an obligate piscivore, however, so can't have been too ungainly on dry land. Basically it would be nice to go and have a look, please.

There's a handy size guide for big theropod predators here. Why the silly sod at the front is waving, I have no idea. Run, you bloody idiot!

Day 12: Hesperonychus dates from about 75 million years ago, in Canada. It was a microraptor, a line of small, birdlike dinosaurs, but quite a bit younger than the others, which have so far been found in much older rocks. Hesperonychus seems to have been very plentiful, and was probably a small, scurrying sort of carnivore. Although some of the other microraptors appear to have been capable of flight, at least to a degree, Hesperonychus probably couldn't. It probably had wings of some kind though, used for balance when running, and perhaps for display.

Day 10: Who doesn't love Styracosaurus albertensis? Less well known than its fellow ceratopsid Triceratops horridus, Styracosaurus was from the later Cretaceous (about 75 million years ago), in Canada, and looks like a heavy metal version of its more famous, and more recent, cousin. Seriously though, it's way cooler (image here). The frill is probably more for display than anything else, so it's debatable as to whether it could have done anything with those horn-like projections, but it's still fab.