Ever heard of Brachytrachelopan? How about Linhenykus? Or Panphagia, Jobaria or Polacanthus? Even if you really love dinosaurs (or have an obsessed child) you may not have heard of any of these, but they are indeed all dinosaurs and are among the ranks of animals that include more familiar names like Stegosaurus, Allosaurus and Diplodocus.
It is easy enough to throw out a bunch of obscure dinosaur names, of course, but the point I'd like to make is just how under-appreciated dinosaur diversity is.
Dinosaur fossils that are recognised as being distinct do of course get named as new genera and species, and that list is ever growing. You will regularly see a report in the media announcing yet another new dinosaur, but these generally require some kind of hook to have attracted the attention of the journos and not slip under the radar as just another New-a-saurus.
Those who keep up to date with more specialist outlets will know that in fact the rate of discovery is faster, with more species being identified than ever break into the mainstream media – the rate is about one a week and has been holding at this level for years. There are hundreds more dinosaurs known now than even some of the most recent books would say.
While the rate of discovery is perhaps higher now than it has ever been before, palaeontologists have only been naming species for the past 200 years and to date, birds aside, there are around 2,000 species of dinosaur. That might be rather fewer than say modern mammals (around 6,000 species) or birds (around 10,000 species) but then birds and mammals have had rather a large historical headstart when it comes to naming them, and most species of bird don't have to be found through weeks of exploring and digging in a desert.
In short, the numbers are perhaps already impressive, but given the limitations imposed by the fossil record (we can't identify species through their genes, colours, behaviour or the like as we can with some modern animals) this is a serious achievement.
The sheer number of species recovered may itself be notable, but the diversity of forms encompassed in that is probably also under-appreciated. Dinosaurs are famous not just for the huge sizes reached by many, but also their weird and wonderful body types. Animals like Diplodocus, Spinosaurus or Triceratops might seem odd, but there are other dinosaurs out there that stand out just as much compared with their relatives or are simply odd in their own right.
Consider the alvarezsaurs. These bipedal dinosaurs were mostly tiny, around the size of a chicken, and were close relatives of the first birds. Although there were plenty of small and fast dinosaurs around, the alvarezsaurs were not only fast, but would cover the ground without wasting much energy, as seen by various adaptations in their skeleton to stiffen up the body.
Such adaptations are useful when your diet of ants or termites demands you move from nest to nest regularly to find food. We know the alvarezsaurs were ant-eaters from their incredibly specialised arms - an absolutely giant claw on one finger (with the other fingers being reduced or even lost) and short but powerful arms, with a special lever joint in the elbow to apply the power to get to their dinner.
Miniature, ant-eating, super-efficient runners? It's hardly the classic picture of a dinosaur, yet these were a diverse group and representatives are known from Asia, Europe and both North and South America. They were no evolutionary one-off, or something that only survived for a short time in a single place, but were a significant part of a great many dinosaur ecosystems.
The sauropod dinosaurs are known for their huge bodies, long necks and tails and tiny heads, but even with this easily recognisable blueprint, there were some fantastic divergences in this herbivorous group. The dicraeosaurs are the most obvious one, small for sauropods being more rhino or elephant-sized (compared with many of their cousins which were anything up to 50 tonnes) they also had very short necks and presumably grazed low growing plants rather then having the capacity to reach up for high foliage.
At the other end of the scale are Mamenchisaurus and its nearest relatives. Even in a group generally characterized by having a long neck, these were outstanding – half their total length (including the tail) could be neck. In the largest, this meant a neck in excess of 10 metres long.
While we continue to be amazed by dinosaurs, be it through the sheer size of the giants, or the bizarre ornaments and horns of others, dinosaurs are rather more diverse and incredible than generally realised. New finds and research continue to add to their ranks and ever more interesting and unusual animals are being discovered. It's not just Tyrannosaurus and Triceratops, but dinosaurs run the full range from Aardonyx to Zupaysaurus.
David Hone blogs at Archosaur musings