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Fixing Massospondylus

March 7, 2011 9 comments

If you have an interest in dinosaurs you will have heard of Massospondylus. It appears in many popular dinosaur books, is regarded as one of the commonest dinosaurs in southern Africa, and has numerous nearly complete skeletons and skulls attributed to it. There are even fossil eggs with complete articulated embryonic skeletons inside that are thought to belong to this species. But what of the type specimen; the official name bearer of the species?

What is a type specimen?

When other specimens are referred to Massospondylus, specifically Massospondylus carinatus, we are proposing the hypothesis that the referred specimen belongs to the same species (whatever that is*) as the type specimen. As so often transpires, the name Massospondylus carinatus was coined early in the history of dinosaur studies, on material that, nowadays, we probably wouldn’t even bother to collect.

What is the problem with Massopsondylus?

Indeed the type specimens of Massospondylus carinatus are, or more correctly were, a paltry pile of damaged vertebrae that were collected off the surface of an outcrop on the Farm Beauchef Abbey, near the town of Harrismith in what is now the Free State Province of South Africa.

Perhaps the best piece from the type series of Massospondylus carinatus

A total collection of 56 postcranial bones from this site were donated to the Hunterian Museum of the Royal College of Surgeons in London. These were described by the famous anatomist, and creator of the name ‘dinosaur’, Sir Richard Owen in 1854. Owen selected five vertebrae from this collection as positively belonging to his new species Massospondylus carinatus. These five vertebrae then became the type specimens (when there is more than a single specimen we call them syntypes) of the species.

Now this where a major problem arises. These vertebrae (we now know them to be neck vertebrae although Owen mistakenly took them for tail vertebrae) are no different from the neck vertebrae of a host of early sauropodomorph dinosaurs such as Adeopapposaurus, Coloradisaurus and Lufengosaurus. Of course tiny differences might be able to be picked out if one looked hard enough but these differences are likely to be subsumed by larger the range of variation seen between individuals of the same species. Furthermore there is more than one species lurking amongst the Massospondylus-like sauropodomorphs of the Early Jurassic of southern Africa. Massospondylus kaalae is one these, and there may well be others. Deciding which of these is represented by the types is impossible.

So what to do? There are three courses of action: 1. Resurrect one of the old presumed synonyms of Massospondylus carinatus as a replacement name. There are certainly plenty of these but each and every one of them is based on material that is almost as inadequate as the original syntypes. 2. Invent a brand new name and apply it to one of the more complete specimens now known. 3. Designate a neotype: That is, take the name Massospondylus carinatus, decouple t from the syntype series and reattach it to one of the more complete specimens. The latter of the three options has the great advantage of causing absolutely no taxonomic disruptions that would ensue if a new and unfamiliar name were to be applied to this well-known taxon.

Usually option three requires a petition to the ICZN, which is gazetted in their bulletin, subjected to public commentary, either for or against, and eventually voted on by the ICZN before final ratification or dismissal. This is a long, slow process but nevertheless the route that Paul Barrett and I favoured. So we set about preparing a formal application to the ICZN to designate a neotype for Massospondylus. Much to my surprise the application was turned down, not because the ICZN didn’t think we had sufficient grounds to justify the designation of a neotype but because a formal petition wasn’t required in this case. You see, in a twist of fate the original syntypes were destroyed during a German bombing raid over London during World War II. Nevertheless they were survived by a series of illustrations and plaster casts.

Some more of the Beauchef Abbey collection preserved as these plaster casts held in the South African Museum, Capetown.

I had thought these were sufficient to act as types, after all the types of Spinosaurus aegytiacus are now reduced to illustrations, thanks to an allied bombing raid in the same war. However they are not, and a neotype can be designated without petition to the ICZN. This is may be the only case where specimen destruction via bombing has actually helped the science a little bit.

So finally our designation of a neotype has been published  in Palaeontologia africana. The specimen we selected is a beaut – BP/1/4934, or ‘Big Momma’ as she is affectionately known. So Massospondylus has been saved, it is no longer in danger of being thrown away as yet another nomen dubium and will forever be one of the best known dinosaurs.

The skull of 'Big Momma', now the type specimen of Massospondylus carinatus

The whole skeleton, or at least as much of it as was preserved

Reference

Yates, A. M. and Barrett, P. M. 2011 (for 2010).  Massospondylus carinatus Owen 1854 (Dinosauria, Sauropodomorpha): proposed conservation of usage by designation of a neotype. Palaeontologia africana 45: 7-10.

*Species concepts in palaeontology are a whole ‘nother can of worms I’m not going to say too much about. Just that I personally prefer concepts based on the biological species concept, that is species are populations linked by interbreeding. So yes asexual organisms would not consist of species, just clades and that to recognise species in extinct populations we would have to use what little proxies for interbreeding as we can find.

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