In the interests of open sourcing, the following skeletal reconstructions and descriptions are CC-BY. This means they are entirely open-access, and you may do whatever you wish with them so long as you attribute the material to me. You do NOT need to source me when you make a drawing based on them, although linking back to the source and my name is a nice thing.
These illustrations are being prepared for a forthcoming book on dinosaurs of the British Isles, but I retain the rights, and to that I continue my quest to make these freely available. Enjoy.
A Whale of a Tail
There was no “kraken” in Greek mythology, but Desmond Davis’ 1981 smash Clash of the Titans had such a following, and the phrase “Release the Kraken” (uttered by Sir Laurence Olivier) was so hugely popular, that the remake needed it. And it was fun. But in the original story, the maiden Andromeda was chained to a rock as a sacrifice to the great monster Ketos, a sea monster it may be said was inspired by stories of great whales breaching in deep water. The concept of Ketos as a great monster of uncertain affiliation, and relative vagueness about what beasties actually lurked in the deep, suggested to the 1800s researchers in England that any great, titanic creature can be comaprable. Upon finding the remains of a giant sauropod, the evocation of a great aquatic monster was given, and so the Cetiosaurus was born. The term “ketos” in Greek now applies to whales, and while it grants us our term “cetacean” it was also a term meant to suggest giant reptilian things as well, and the describer thought it was a crocodilian.
There’s a lot to making names and revising them over time when it comes to dinosaurs, and this convention is alive and well today, what with the occasional dinosaur name being preoccupied by some insect or some nematode. But in the 1800s, partly due to the lack of communication amongst the continentals and with England, and also due to the relatively lax conventions on what rules might govern naming things, a variety of animals had to earn whole new names to “work.” Streptospondylus oxoniensis was one such animal, originally named as a new species of Streptospondylus, itself based on a vaguely dinosaurian specimen from France. When it was perceived this specimen was crocodilian, or really just a lump of crappy bones, the animal was renamed Eustreptospondylus, and thus my first favorite dinosaur ever was born.
[Edit: Pardon, I had the data on this mixed up, and regret the error.
The specimen was initially referred to Streptospondylus in general, but later analysis resulted in the specimen's removal and referral to a new binomen entirely. Walker's Eustreptospondylus oxoniensis was created out of whole cloth, and due to its better preservation earned the monicker "true Streptospondylus," rather than be a revision of an older name. Oxoniensis was thus coined simultaneous.]
Bizarrely, it not only turned out that Streptospondylus altdorfensis, again based on some crappy material, was dinosaurian, it was a potentially valid taxon that was itself quite closely related to Eustreptospondylus oxoniensis. In the effort to segregate the two, researchers may have pulled them too far apart, and by the virtue of their time were unable to correctly evaluate the distinctiveness of the material. Now, they have come back around and met again.
Stegosaurs range across the northern Hemisphere, and are known from the Jurassic into the Cretaceous, but weren’t very successful compared to their ankylosaurian relatives. And stegosaurs seem fairly significant looking what with all of their tall plates and huge tail spikes. They are tall and narrow; ankylosaurs are low and fat. But some of the earlier stegosaurs are not so … stegosaurian. Some looked very ankylosaur-like, with large forelimbs, longish necks, and spiny armaments down the back rather than just giant plates and a thagomizer at one end.
The first fully-recognized stegosaur is Dacentrurus armatus, named from the Kimmeridge Clay of England, from the Late Jurassic. It seems vaguely similar to Kentrosaurus from Africa and roughly the same age. But few specimens of Dacentrurus armatus are known. Some specimens referred to it have actually come across the Jurassic/Cretaceous boundary, from the Weald and from continental Europe. Originally named Omosaurus, the name belonged to a crocodilians; yet by the time this was recognized, half a dozen species had been named on the basis of stegosaur-like bones or armor. Many of these were split off, but some remain. A complete specimen is not known, and many scattered remains are difficult to verify without understanding range of variation. It is conventional to assume many European Jurassic/Cretaceous spanning stegosaurs are or are very similar to Dacentrurus armatus, and it is these specimens which provide the basis of the reconstruction. A shoulder spike (which can also be a hip spike) is placed there in keeping with similarities to similar spikes found in other stegosaurs.
It’s like a totally different animal, man!