Sunday, June 1, 2014

The generic history of dinosaur paleontology: 1699 to 1869

A few months ago, not long after I started writing this blog, I thought it might be fun to do a monthly roundup of news in dinosaur paleontology. The month was February, and almost nothing happened. Well, there was a publication on an extension of the geologic range of Polacanthus, which is probably much more interesting to me than to practically anyone else, but that can't really hold a whole month. I might as well just drop the pretense and post on Polacanthus. One day I will be tempted to do so, and it will be a terrible post. Fate has ordained it.

I'm sorry—the point was that I wanted to write about dinosaurs, and there wasn't much happening. It occurred to me that things had been slowing down the past couple of years in dinosaur paleontology. Because my first instincts are usually wrong, I started casting around for some way to test this. There is a variety of things that you could count: number of dinosaur-relevant publications, number of active researchers, number of authors in papers, number of species and genera named, and so forth. I suppose ideally you would count all of these things and come up with a master statistic like Wins Above Replacement, except we'd have to muck with the name so the acronym would be DINO, and then there'd be different methods of weighing the components and factoring in how the field has changed since the 1820s, and Miguel Cabrera would still end up winning the MVP even though he has never published on dinosaurs and there is no MVP. (Calvin was wrong; there are not "many lucrative paleontology prizes," even if you were to uncover a Calvinosaurus.)

One quick and dirty way of looking at the question is how many new genera are published in a year. This method has in its favor the fact that finding the information and dealing with the numbers is relatively easy. The primary drawback is that it doesn't cover all publication activity: you miss everything that doesn't include a new genus. Up to about 1980 or so, this is not as big a deal, because taxonomy was the focus of publication. You still miss some species, but fortunately for our purposes sometime during the first few decades of the 20th century people working on dinosaurs seem to have decided that new species deserved new genera. The genus-first thing has become nearly an ironclad rule, except for Mamenchisaurus, Omeisaurus, and Psittacosaurus. Publication patterns shifted during the 1970s and 1980s, and papers on topics like taphonomy and growth patterns and bone structure and pathologies became more commonplace. Other differences include a much more cosmopolitan distribution of subjects and authors, and the prevalence of multi-author publications. It's becoming increasingly rare to have even two authors (let alone one author) as the number of people active in the field has grown, researchers become more specialized, and collaboration become easier.

Given the limitations of a genera count, what good is it in regards to my question? Well, for one thing, it turns out that going through genera chronologically is a great way to get a qualitative look at the history of the field. Thus began the final evolution of the concept I'd had.

The simplest way to look at genera is to go through George Olshevsky's Dinosaur Genera List. There are other sources, but many of them are ancestrally tied to some incarnation of this list. There are occasionally discrepancies with year of publication for some names, particularly in recent years where publications can appear online several years before the print version, but are not considered official by the International Commission on Zoological Nomenclature. The Dinosaur Genera List considers them valid, and frankly my sympathies lie that way, too. The list is only for classic dinosaurs (i.e. not birds), which is fine for my purposes; I only make an exception for Archaeopteryx.

The first name on the DGL is Rutellum, used in 1699. This is so far back that it doesn't actually count as an official, ICZN-sanctioned name. It's pre-Linnean (no "kings play chess on funny green squares") by nearly 60 years, and pre-Dinosauria by more than 140 years. Obviously, it was not recognized as a dinosaur in 1699, but we can see that the illustrated fossil was the tooth of a "cetiosaur"-type sauropod. The next name is, er, Scrotum, used in 1763 for what we now can recognize as the end of a theropod thigh bone. Again, it's not quite a sanctioned name, probably only intended as a descriptive caption.

Skip forward another 60 years and we hit familiar names, Megalosaurus (1824) and Iguanodon (1825) (and one nomen nudum, or "naked name", one which has been used somewhere but not formally published). This is looking promising, even if it will take a while before either are known well enough to make a decent restoration. The 1830s have eleven genera that have been considered dinosaurs at one time or another, although only five are still considered to be dinosaurian and not a spectacularly poor probable typo for Iguanodon: Streptospondylus (1830), Hylaeosaurus (1833), Thecodontosaurus (1836), Plateosaurus (1837), and Poekilopleuron (1838) (don't worry, I'm not going to put up every one of these). The problem at this point, of course, is that "dinosaur" as a classification does not enter the scene until 1842, and the understanding of "dinosaur" is pretty fuzzy for another few decades, so a lot of things come and go as "dinosaurs". The diversity is not bad: out of seven genera and two sort-of names, we have a sauropod, two quite different "prosauropods", an armored dinosaur, an ornithopod, and, well, four large theropods that are fairly closely related. Incidentally, if you want a compact guide to keep these things straight, you can't really do better that the supplement to Thomas Holtz' Dinosaurs. In terms of time, we've got the three periods of the Mesozoic (the Triassic, Jurassic, and Cretaceous) covered, although if you parse it further we're limited to the Late Triassic, the Middle Jurassic, and the Early Cretaceous. Geographically, we've got England, France, and what is in the process of becoming Germany. We could throw in this thing called Macrodontophion that's probably a conical invertebrate fossil, but which has sometimes been considered a theropod dinosaur tooth, and we'd pick up Ukraine. Gideon Mantell becomes the first person to describe two dinosaur genera with Iguanodon and Hylaeosaurus.

Eighteen more genera are named between 1840 and 1849, although again most of them are only on the list because someone mistook them for a dinosaur at some time in the past 160–170 years. Only four have survived to make the dinosaur encyclopedias: Cardiodon (1841), Cetiosaurus (1841), Suchosaurus (1841), and Regnosaurus (1848). There's no major changes in the stratigraphic or geographic diversity, and in terms of biological diversity we're only adding stegosaurs to the armored dinosaurs. The big change for the 1840s is the development of the conceptual box "dinosaur".

The DGL lists 26 new names between 1850 and 1859. At this point, things are getting complicated. People have been working the same areas for years, and with limited comparative material are renaming things that have already been described (Dinosaurus/Gresslyosaurus [1856] versus Plateosaurus). Owen, fresh off a number of questionable choices in naming species of Cetiosaurus, jumps into the exciting world of generic splitting by naming Massospondylus, Leptospondylus, and Pachyspondylus in 1854, all now regarded as Massospondylus. Twenty of the 26 are still recognized as dinosaurian, and several are very well-known today. We get our first small theropods (Nuthetes in 1854, followed by Troodon in 1856 and Compsognathus in 1859), first representative of the bonehead/horned dinosaur line (Stenopelix in 1857), first tyrannosaur (Deinodon in 1856), and first hadrosaurs (Thespesius and Trachodon in 1856, followed by Hadrosaurus in 1859). Compsognathus and Hadrosaurus are the first genera named from major parts of the skeleton. Geographically, the first forms from outside of Europe are named. North America comes in "first", with Clepsysaurus (now known to be a phytosaur, a broadly crocodile-like Triassic reptile) from Pennsylvania in 1851, but its first true dinosaurian genera are a group of four named from teeth in 1856 (Palaeoscincus, Thespesius, Trachodon, and Troodon, which also expand dinosaurs into the Late Cretaceous). Southern Africa is represented by Massospondylus and its two less accomplished friends from 1854. The use of teeth in dinosaur taxonomy will continue without reservation for a few more decades, until enough skulls are known to show that in most cases, dinosaur teeth aren't particularly informative in terms of species and genera.

Twenty-eight genera are listed for 1860 to 1869, 23 of which represent dinosaurs and about seven of which are particularly notable (Archaeopteryx [1861], Echinodon [1861], Megadactylus [eventually Anchisaurus] [1865], Polacanthus [1865], Laelaps [where we meet Edward Drinker Cope; eventually Dryptosaurus] [1866], Hypsilophodon [1869], and Rhabdodon [1869]). The 1860s is the last decade that is thoroughly dominated by Europe, and as we can see with Archaeopteryx it went out with a bang. When we turn the page to the 1870s and 1880s, it's a sea of Cope and O.C. Marsh rampaging across the United States.

Some random thoughts on the early history of dinosaur study:
  • Eighty-eight names so far, of which 57 are identifiable as dinosaurs. About half of that total still retain some currency in the literature.
  • The thirty-one gate-crashers are mostly other archosaurs or phytosaurs, the next best thing. A couple of pelycosaurs and therapsids are mixed in as well. Barring discovery of the true nature of Macrodontophion, the most exotic interloper is the unusually toothed early whale Squalodon (1840), once thought to be an iguanodont. Non-dinosaurian creatures getting mistaken for dinosaurs will decline as stratigraphy becomes better known, the pool of fossils for comparison expands, and the concept of "dinosaur" solidifies. The knotty area today is the Triassic, where a lot of creatures experimented with dinosaur-like postures and teeth.
  • The letters F, J, K, Q, U, V, W, X, and Y are unavailable for starting genera. In fact, you wouldn't know that the letters F, J, Q, V, and W exist at all. A lot of this is due to the Latin and Greek alphabets, although it doesn't explain why more than a tenth of all dinosaurian genera start with A.
  • In terms of modern nations, we've only got France, Germany, South Africa, the UK, and the USA. The great majority of the genera are published in English, and the authors are all in Europe or the United States. (Spoiler alert: The first person based outside of either area to name a dinosaur will be Florentino Ameghino in 1899. The first woman will be Mignon Talbot in 1911.)
  • Richard Owen, noted for coining Dinosauria, is the dominant figure in terms of taxonomy, being responsible in one way or another for 13 of the genera.
  • Henry Riley and Samuel Stutchbury are the first "team". In 1836 they described Palaeosaurus (nondinosaurian; revised to Paleosaurus in 1840 because Palaeosaurus was already in use) and Thecodontosaurus. Double authors does not become common until the 1970s, and the first name with more than two authors appears to be Gallimimus in 1972 (Osmólska, Roniewicz, and Barsbold).
  • Still no clearly horned or dome-headed dinosaurs, although that's fixed soon. In fact, if you are counting species, you will become bored or infuriated with what Marsh is about to do. Theropod diversity is limited, and we're still missing the wing of sauropods made up of Diplodocus and friends.
  • The Late Triassic, Early Jurassic, Middle Jurassic, Late Jurassic, Early Cretaceous, and Late Cretaceous are all represented.
  • Best "vintages"? For quantity, 1856 (9 genera, including the nucleus of North American dinosaurs). Quality is a matter of taste, but 1859 gets you Compsognathus, Hadrosaurus, and Scelidosaurus.
Next up: the "bone wars" era.

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