The Validity of Lambeosaurus - Anybody Know A Good Lawyer?

Reconstruction of Didanodon altidens specimen ROM 794 (aka Lambeosaurus lambei,
aka Procheneosaurus praeceps) by Matt Martyniuk, all rights reserved.

I've talked a lot on this blog about my personal justifications for using "old fashioned" names for many groups or species of stem-birds. In many cases, names which were in common use during the 19th and early 20th centuries were replaced later by one or two influential scientists for reasons which don't really hold up when you look at the codes that govern naming in biology. For example, Manospondylus gigas may currently be the correct name for the theropod we know and love as Tyrannosaurus rex, but this possibility has almost never been discussed because everybody assumes it's a nomen oblitum - a name out of use for so long that it becomes automatically invalid under the International Code of Zoological Nomenclature (ICZN). Note the word "assume"--as I've written before, most people, even working scientists, don't really know what criteria must be met to classify a name as obsolete.

The name of one very well-known dinosaur is in such a sorry state that it's like the Manosponylus / Tyrannosaurus debacle squared. The genus Lambeosaurus, a well-known hadrosaurid with a distinctive squared-off crest with a backward-pointed prong, was named twice prior getting its popular moniker, and neither of those names can be considered obsolete, since they were both coined during the 20th century.

The first name given to fossil material (in this case a jaw) now universally attributed to Lambeosaurus was Didanodon. In a 2006 review of hadrosaurs, Lund and Gates stated (without discussion) that the genus and its type species, Didanodon altidens, were nomina nuda, or "naked names" lacking the proper description necessary to establish them. But is this really the case?

Supporting the Dinosaur/Bird Link in the Era of the MANIAC

I'm posting this more as an open question than a statement of my own opinion, so comments appreciated!

A new paper out in Paleobiology by Verracchio et al. describes the porosity of Troodon formosus eggs and uses the data as evidence to support the hypothesis that troodontids brooded their eggs, like modern birds and other known maniraptorans, rather than burying them, like crocodilians and some other modern birds. In and of itself, this conclusion is interesting in that it pretty much solidifies nest brooding (as opposed to burial) as the ancestral trait for modern birds, and for maniraptorans (or at least chuniaoans*) in general.

Study coauthor Darla Zelenitsky with Troodon formosus nest. Photo by Jay Im, University of Calgary.

I hate to admit it, but my first thought when reading the headline of this news article from PhysOrg was that, yeah, we all assumed that anyway. The unspoken "rule of cool" is that science tends to be more exciting when we find evidence that contradicts previously well-supported hypotheses, rather than confirming hypotheses we all took for granted. Sure, finding the Higgs-Boson was exciting, but not nearly as exciting as not finding it, which could have led to new physics. I assumed, and I'm sure many others did as well, that troodontids brooded their eggs, based on the reasonably secure hypothesis that oviraptorids (which are known to have done so) are more basal. This behavior in troodontids was even depicted nicely in 2011's Dinosaur Revolution. So score another one for phylogenetic bracketing!

(Of course, this is not to imply that all chuniaoans must have brooded their eggs. It's entirely possible that reversals to burial nesting occurred, as with modern megapodes, and this seems especially likely for very large species like some dromaeosaurines. But the odds that any given chuniaoan would not be a brooder are low.)

Arctic troodontids, anatomy based on Troodon formosus.
Matt Martyniuk, all rights reserved.

Aside from all that, the assertion in the PhysOrg headline struck me as particularly meaningless. How could a study of troodontid brooding lend support to the dinosaur/bird hypothesis? This statement would have been accurate a decade ago, but not today. The reason is the moving goalposts of the dinosaur/bird opposition.

What's A Monoclonius?

Hypothetical restoration of an adult Monoclonius crassus,
by Matt Martyniuk. All rights reserved.

Monoclonius crassus is an iconic ceratopsian, a fixture of many 1970s era dinosaur books, which owes its status almost completely to another species. 

I grew up with depictions of Monoclonius in media like Phil Tippet's short film Prehistoric Beast and toys like the DinoRiders figure. Like most representations of Monoclonius in popular culture, these were based on specimens now classified as Centrosaurus apertus (though, actually, that DinoRider looks like it has a genuinely Monoclonius-type frill, long, straight, and unadorned). 

Originally known only from teeth and a fragmentary frill and nasal horn, the Monoclonius was one of the first ceratopsians known to science, found by E.D. Cope in 1876 and named for its configuration of tooth roots ("single sprout" as opposed to the "double sprout" of Diclonius, now known to pertain to a hadrosaur). 

Like many of Cope's species, Monoclonius was not recognized for what it really was (a "horned dinosaur") until more complete remains from other ceratopsians likeTriceratops were found by Cope's rival O.C. Marsh. Monoclonius itself remaned enigmatic for many years, though the idea of a Triceratops-like ceratopsian with a single large nasal horn was used by Charles R. Knight in his famous painting of Cope's other dubious ceratopsian, Agathaumas. Knight also incorporated spiny dermal armor associated with some supposed Monoclonius remains, though at least some of this material was later shown to belong to ankylosaurs and pachycephalosaurs.

Monoclonius became iconic when complete skeletons of ceratopsians were found in the Judith River/Dinosaur Park Formation of Montana/Alberta. In the early 1900s, C.H. Sternberg (who had co-discovered the orgiinal Monoclonius fossils with Cope) established that complete specimens classified by Lawrence Lambe as Centrosaurus apertus (and some of which were considered to be Monoclonius and which had already been used to form a picture of that animal) were a distinct species. After this, the genus Monoclonius was dismantled, with former specimens re-assigned to either new or recently established centrosaurine genera.

Matters were complicated by the discovery of the drastic changes centrosaurines went through as they grew, and today the distinctive Monoclonius specimens are generally considered juvenile centrosaurines. Zach Miller has done an awesome rendering of a centrosaurine growth series showing where a traditional "Monoclonius" specimen fits into the sequence. 

Skull of the subadult Monoclonius lowei. Note the three prominent projections at the rear of the
 parietal frill. Incipient styracosaur-like spikes?

However, known specimens of Monoclonius aren't a perfect match for juveniles of the contemporary Einiosaurus, as Miller notes. The long, generally flattened frill with larger incipient spikes at the first three positions of the the parietal (Ryan 2006) are reminiscant of Styracosaurus and Einiosaurus, all of about the same geological age. The large size of a specimen sometimes referred to the distinct species Monoclonius lowei compares with some pachyrhinosaurs like the contemporary Achelousaurus, and while these do begin life with a small nasal horn that later develops into a boss, and though it isn't backward-cureved, such drastic changes during ontogony are known in other ceratopsians. It may be that Monoclonius is a juvenile form of (and therefore a senior synonym of) one of these centrosaurines, or it may be a valid species similar to both, possibly a transitional form between centrosaurin-type centrosaurs and pachyrhinosaurs. Ironically, though long mixed up with that genus, Monoclonius doesn't seem to be as great a match for Centrosaurus itself.

In my restoration of a hypothetical, mature Monoclonius (above), I made it generally styracosaur-like, though with more einiosaur-like parietal spikes, and these could alternately be seen as styracosaur parietal spikes which are not yet fully grown. In this way I've tried to hedge my bets: this Monoclonius could either be a mature, intermediate stage between styracosaurs and einiosaurs, or simply an immature but very large styracosaur. 

The nasal horn is restored as styracosaur-like as well, a conservative growth trajectory for the shorter, recurved nose horn seen in subadult specimens of M. crassus and M. lowei. However, it's entirely possible that as the nasal horn grew, it swept forward into the hook-like horn of Einiosaurus or even flattened and thickened into the nasal boss seen in Achelousaurus. Both of those pachyrhinosaurs have long parietal spikes like Monoclonius seems to have had, though both only had a single pair jutting from the back of the frill, while Monoclonius seems to have been developing at least three. Though, again, it's possible the transformation was more extreme than I'm assuming for my illustration, and that these incipient parietal horns were resorbed during growth like the epiparietals of chasmosaurines (e.g. Triceratops).

Rather than the centrosaur-like Monoclonius of my childhood, it looks like this fairly plain-looking ceratopsian grew up into something a bit more spectacular. But we'll need further study and, hopefully, more specimens to find out exactly what, and exactly how extreme, that transformation may have been.

* Ryan, M.J. (2006). "The status of the problematic taxon Monoclonius (Ornithischia: Ceratopsidae) and the recognition of adult-sized dinosaur taxa." Geological Society of America Abstracts with Programs, 38(4): 62.

Clever Girl...

In honor of the Jurassic Park re-release...

Who Cares About "Dinosaurs"?

Question: Who cares about dinosaurs?

Short Answer: Marketing departments and monster movie fans.

Above: Not what most people think of when you say "dinosaur."
(Ashdown Maniraptoran by Matt Martyniuk, all rights reserved).

Long Answer:
This is a philosophical issue that's been on my mind for a while now, inspired by some recent and heated debates over the content of the Dinosaur article at Wikipedia. It also seems to be simmering in the background of a lot of discussions about the recent suggestion that Jurassic Park 4 will not feature modern, scientifically accurate dinosaurians.

No Feathers

As many of you know by now, Jurassic Park 4 director Colin Trevorrow has (basically) announced via tweet that JP4 would not feature feathered dinosaurs but would stick to the 1980s designs of the original film.

Lots of opinions are flying around paleo blogs and they all raise good points. Andrea Cau has been one of the few to defend the decision by noting that changing the dinosaurs would upset the continuity of the films, such as it is (it's not like we're talking about Lord of the Rings style mythology here). Brian Switek has countered that each previous film has completely re-designed the "raptors" anyway with no in-universe explanation. This has even been jarring in the films themselves. At the beginning of the third film, Sam Neil's character Alan Grant has a dream about a raptor, but it's one of the new raptors (with a totally different skull featuring lachrymal horns, new color scheme, and those bizarre psittacosaur-like quills on the neck), not the raptors he or the audience should remember from JP1.

Anyway, it's obvious the producers don't give a hoot about continuity and are trying to appease the JP fans who love the classic dinosaur designs. That's understandable, but it should also be understandable why a significant portion of the fan base is upset. JP is what got many of us into paleontology in the first place, and the first film went out of its way to emphasize the latest science. Steven Spielberg could have gone with dinosaurs the audience expected in 1993: tripodal, tail-dragging, sluggish reptilian beasts. Instead, he made JP the coming out party for the Dinosaur Renaissance, introducing active, bird-like, Bakkerian dinosaurs to a mass audience for the first time in defiance of expectations (dialogue from the film quickly addresses the inaccuracy of the then-classic dinosaurs as well, like noting that the brachiosaur is warm-blooded and doesn't live in swamps).

So it's a bit sad that JP has eaten its own tail and become the self-perpetuating font of inaccurate science the original film was designed to destroy. The franchise is now a slave to its own cannon and the expectations of its audience, rather than having the guts to challenge those expectations. It will inevitably have to rely more and more on cheap built-in loopholes like frog DNA to briefly explain why the dinosaurs are monstrous relics of a bygone era of science less accurate than the CGI characters on a popular children's show.

As Cau noted in his comments, the only thing that could revitalize the series is a reboot. Here's hoping!

Double Dewlap! What Does It Mean?

My new book A Field Guide to Mesozoic Birds and Other Winged Dinosaurs is now available! The book can be purchased via Amazon or CreateSpace. A PDF version is available via Lulu (for those of you reading this via RSS, click through to the Web article for handy links on the right side of the post!).

A lot has been made recently about the "new era" dawning in paleoart (or paleontography, or whatever your preferred term is). A move away from the shrink-wrapped and hyper-anatomical artwork that characterized much of the Dinosaur Renaissance. While attention to this new movement has focused mainly on the artwork in the fantastic new book All Yesterdays, Andrea Cau rightfully pointed out on his blog that other artwork has been appearing in this same vein for a while now (though perhaps lacking the publicity it deserves). Cau highlighted the amazing paleo paintings of artist Emiliano Troco, including the rather audacious reconstruction of an Apatosaurus with double dewlap-like structures on the neck.

Apatosaurus by Emiliano Troco.

I guess it's an argument for either the collective consciousness, or that there are in fact a limited number of outlandish yet plausible things you can do when restoring sauropod necks, that I came up with a very similar idea many years ago! My execution of the double dewlap sauropod was somewhat... lacking in technical skill compared to Troco's, but you have to admit it is kind of funny that two people independently came up with such a bizarre idea. After a bit of searching I managed to find a really bad scan of my old sketch, presented below or your amusement!

My 2002 drawing of an Isisaurus (Titanosaurus colberti at the time) with double dewlaps. Based on a skeletal by Jaime Headden.