Xenon's Seventh Circle

Day 21: I'm not sure why, but lately all my dinosaurs seem to be starting with 'p'. Here's another. You've got to love Pachycephalosaurus wyomingensis. Imagine a mediaeval monk, complete with tonsure, then sprinkle his head with bony knobs, and you're... okay, not very close to Pachycephalosaurus, but it's a start. Not a big dinosaur - this one might make it to your shoulders, depending on how tall you are - but what it lacked in size, it seems to have made up for in attitude. Pachycephalosaurus is famous for its skull, and rightly so. Bristling with bumps, and with crowns as much as ten inches thick, it looks like they were made for fighting - specifically, for headbutting. Perhaps they fought each other the way that goats do today. Perhaps they deterred would-predators. Perhaps both. Either way, without some serious protection, a knock from a skull like that could do some damage.

An interesting thing about Pachycephalosaurus - if you need more interesting than a skull that would put a dragon to shame - is that, whilst long assumed to be herbivorous (its teeth were the flat, grinding molars familiar to herbivores) a recent skull discovery also bore very definite canines. So, was it an omnivore? Was Pachycephalosaurus charging about the late Cretaceous (North America, c. 67 million years ago), munching on smaller dinosaurs? Maybe it headbutted them to death. Possibly further discoveries will shed a little light. In the meantime, Pachycephalosaurus skulls. Admire, and mourn your own skully shortcomings.

Day 19: Parasaurolophus walkeri was a hadrosaurid, a family of dinosaurs that tended to go in for head ornaments. In the case of Parasaurolophus, this meant a long, hollow crest that was connected to the nasal passages, and thus seems to have been capable of producing noise. This rather suggests that Parasaurolophus went about hooting a lot. The crests should have been capable of making different noises (alarm-raising, parental communication with young, mating displays, etc), and you can hear a recreation here.

The hadrosaurids were herbivorous, and seem to have travelled in herds. They've been called "the cattle of the Cretaceous" due to their ubiquity, and they seem to have been a major part of the diet of a lot of large, Cretaceous carnivores. Parasaurolophus (North America, c. 75 million years ago) would presumably have been no exception, although at ten metres long it would have been no pushover. It's easy to imagine them living in herds, co-operating to protect their young, and hooting at each other as they went about their business. Due to the vast number of hadrosaurids that existed, they're fairly well known in the fossil record (including skin impressions and even preserved soft tissue). This helps to make the family as a whole much better known to science than some of their fellow dinosaurs. Parasaurolophus fossils are scarcer than those of some other hadrosaurs, but general similarities in the family at large help to give a pretty good picture of how they lived.

Day 17: From Mongolia in the late Cretaceous (around 73 million years ago), Protoceratops andrewsii was an early horned ceratopsid. Unlike its cousins, such as Triceratops and Styracasaurus, it was just a little thing, and far less horny. Specimens have had a tendency to be found en masse, which suggests that they were social creatures. They were also very cute. (Or at least, I think so!)

There's a very famous Protoceratops skeleton found apparently locked in mortal combat with a Velociraptor, which suggests that Velociraptor either preyed on Protoceratops, or - probably more likely - tried to attack their nests. This has led to Protoceratops gaining some notoriety in a world that generally prefers large predators over small herbivores.

Here's a picture of a Protoceratops watching over a hatching nest of its chicks, drawn by Rod Ruth.

Day 15: A dinosaur that needs more love. Kryptops palaios was found in the same rocks as Eocarcharia dinops (see day one), and consequently also came from Niger, c. 110 million years ago. A (probably) carnivorous theropod, it was roughly the height of a tall man. Very few fossils are known for Kryptops, with what there is making it possible to project the shape, and make a few educated guesses about diet and lifestyle. It's not especially glamorous, but there it was, nonetheless, strutting about West Africa in the early Cretaceous. Hopefully some more of it will be found some day.

The name means "old covered face", because the single specimen currently known appears to have had some sort of face covering, possibly of keratin. This might have served the same purpose as a vulture's bald head (easier to keep clean than feathers when you're sticking your head into entrails - although it's also been suggested that it might play a role in thermoregulation), or it may have been something to do with display. It's also been suggested that it might be some sort of mutation or chimera, and that Kryptops might actually be another Eocarcharia. Given the tremendous unlikelihood of a: being decently fossilised, and b: your fossil surviving 110 million years in order to be found, it's seems unlikely that a chance mutation would make it into the fossil record; but of course, it's by no means impossible.

Day 13: The species for which the carcharadonts were named, Carcharodontosaurus saharicus was found (as you might expect) in the Sahara, and dates from the mid-Cretaceous, around 95 million years ago. Although the first fossils of its kind were destroyed during WWII, more have since been found, and the close similarity of the teeth to those of the Carcharodon genus of sharks led to their name. Carcharadontosaurus had a huge skull over a metre and a half long, and was probably slightly larger than T. rex. Its skull wasn't as powerfully built though. As the saying goes, size isn't everything! Not that it couldn't have done a heck of a lot of damage, to pretty much anything it chose.

Day 11: As you can probably guess from its name, Australovenator wintonensis came from Australia, and dates from the later Cretaceous (about 95 million years ago). A smallish hunter, it probably relied on speed more than strength, and as such, rather than having the huge head and massive jaws of some of the more famous carnivorous dinosaurs, Australovenator had what appear to be very agile hands, and more manoeuvrable arms than was normal for its kind. Like all the therapods, it was bipedal, and probably used its hands to hold onto its prey.

Day 09: Tarbosaurus bataar (The Asian T. rex) was slightly smaller than its North American cousin (from current fossil evidence), but just as formidable. It was another of the later dinosaurs, living around 70 million years ago, and some argue that it should be called Tyrannosaurus bataar, given the similarity between it and T. rex. At the moment, Tarbosaurus is holding its own though, as there are enough differences between them to make it appear that both species evolved to suit different environments, and probably slightly different prey. Which I'm glad about, as Tarbosaurus means "alarming lizard", which amuses me, and I should be sorry to lose the name.

Day 07: From Lake Nyasa in the mid-Triassic, some 245 million years ago, Nyasasaurus parringtoni is the oldest known true dinosaur. Like with the evolution from dinosaurs to birds, it can be hard to say when the first dinosaur was, and there's some argument that Spondylosoma may be the oldest. Or it may not be. In the meantime, Nyasasaurus is, unless you're one of those arguing that it's not a dinosaur either. Evolution is complicated. Especially when you only have a few bones.

Day 05: A late dinosaur, from Romania some 70 million years ago, Balaur bondoc is an interesting one. It seems to have come from an island, and shows signs of island dwarfism. It had big, retractable claws on its feet (two on each foot, whereas most of its relatives only had one). Despite that, it appears to have been omnivorous rather than especially fighty, and some palaeontologists have suggested that it might even have been herbivorous, which was rare amongst the therapods. Trapped on an island, it may well have had to adapt to suit its surroundings, so omnivory seems like a good bet.

Day 03: Archaeopteryx, one of the most important dinosaurs in our unfolding understanding of the evolution of therapod dinosaurs into birds. Originally thought to be one of the earliest birds, it's since been reclassified as a dinosaur (and then a bird again, and then a dinosaur again). It's a dinosaur at the moment though, or was last I checked; and zoologically speaking they're the same thing anyway. The problem is, when one line evolves into another, there's no sharp line of delineation, but a series of small steps. So you have the non-avian dinosaurs on one side, the avian dinosaurs on the other, and a lot of murky sliding about betwixt and between. Which is where Archaeopteryx lies. Another German dinosaur this, and again from 150 million years ago, so quite possibly it flew over Sciurumimus, if not particularly gracefully.

Due to scanning elctron microscopy, and the good fortune of some very nice fossil specimens, it's been possible to look at the microscopic structure of Archaeopteryx's feathers, and it's generally assumed that they were black.