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21st Century Dinosaur Revolution

The views expressed are those of the author and are not necessarily those of Scientific American.


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Front cover of the A & C Black edition.

A recent tour of the Natural History Museum (London) bookshop reminded me that my 2009 book, The Great Dinosaur Discoveries (A & C Black in the UK, University of California Press in the USA), is still on sale and in demand. Buy it here on amazon and here on amazon.co.uk. Thoughts on this book (including on its mostly fair coverage in reviews) have been covered before on Tet Zoo (see What they’re saying about The Great Dinosaur Discoveries). I still like it. Naturally, it’s becoming increasingly out of date, and many of the illustrations we had to use aren’t my ideal choices. But overall I’m pleased with the reviews I provided of various key dinosaur discoveries, and of the historical overviews I wrote about the different stages of our knowledge evolution about Mesozoic dinosaurs.

As an example of the latter, below I’ve published the introductory text from the book’s last chapter, titled ‘The 21st Century’. Seeing as this text was written in 2009, it’s lacking reference to numerous discoveries made since. And constraints of space and word count also mean that it doesn’t credit everything it should: no mention of the Ornithischian Revolution, for example. Anyway, the text below appears as it does in the book (Naish 2009). However, I’ve added citations to relevant papers (though not all of them), something I didn’t do in the book for obvious reasons (it’s a popular book, not a semi-technical or technical one).

It's not from The Great Dinosaur Discoveries, but - seeing as I just mentioned ornithischians - I thought I may as well recycle this now somewhat dated cladogram, from Naish & Martill (2001). Back then, we were excited by the possibility that heterodontosaurids might be close to Marginocephalia (yikes, here they're shown as >part of< Marginocephalia). (1) Ornithischia; (2) Lesothosaurus; (3) Genasauria; (4) Thyreophora; (5) Scelidosaurus; (6) Eurypoda; (7) Ankylosauria; (8) Stegosauria; (9) Cerapoda; (10) Marginocephalia; (11) Heterodontosauridae; (12) Pachycephalosauria; (13) Ceratopsia; (14) Ornithopoda; (15) Hypsilophodon; (16) Iguanodontia. Diagram by Darren Naish.

The 21st Century

Primary achievement of the 21st Century: MEMES. This from John Conway's series on Hypsilophodon.

Spectacular dinosaur discoveries continue to be made today. China and Argentina have produced a flurry of unusual new species, but the new generation of palaeontologists specializing in dinosaurs have contined to describe new species from Europe, North America, and elsewhere. Since 2000, we have seen such wonders as the long-snouted maniraptoran Austroraptor, the strange theropod Masiakasaurus, the abelisaurs Rugops, Rajasaurus and Skorpiovenator, the gigantic sauropod Turiasaurus, the dwarf sauropod Europasaurus, and the basal ceratopsians Liaoceratops and Yinlong.

The early 21st century also saw the emergence of a new biomechanics movement, stimulated by new techniques and technologies, that sought to test many of the old assumptions about dinosaur function and behaviour. The bite strength, head postures, neck mobility, arm strength, and running ability of many dinosaurs have been analysed. This work should be seen as part of a broader approach to form and function in animals. The general thinking during much of the 1990s* was that scientists had nothing new to learn from anatomy, and that genetics remained the only biological frontier, but this view has proved mistaken: it turns out that plenty of very basic questions about the anatomy of living animals have never been analysed – and dinosaurs are at the heart of this anatomical revolution.

* This isn’t really correct: the text originally said “late 20th century” and was meant to be a reference to the last few decades of the 20th century, not the 1990s in particular.

Theropod insights

Scipionyx doesn't even get mentioned in The Great Dinosaur Discoveries (hey, nothing personal - it was going to get its own full spread!). Definitely worthy of mention here is the amazing, comprehensive, 281-page monograph on the specimen, published in 2011. A must-own for those seriously interested in Mesozoic theropods.

The discovery of Sinosauropteryx, Caudipteryx and Protarchaeopteryx in the 1990s proved that small theropods were feathered (or, at least, possessed quill-like “proto-feathers”). Beautifully preserved, complete or near-complete small theropods continued to be found during the following decade. Most of these fossils came from the Lower Cretaceous Yixian Formation in China’s Liaoning Province, and most were described by Xu Xing and his colleagues, of the Institute of Vertebrate Paleontology and Paleoanthropology.

The bizarre Microraptor – a small dromaeosaur with long feathers on its  hind limbs as well as the forelimbs – was named in 2000; the tiny, long-fingered Epidendrosaurus saw print in 2002; poorly known Yixianosaurus was described in 2003; and a small troodontid preserved in a sleeping posture, Mei long, was named in 2004. Many other such dinosaurs were named as well, and new, feathered dromaeosaur, oviraptorosaur and therizinosauroid specimens provided much new information on the anatomy and feathery covering of these animals.

Given their position in the theropod cladogram, several groups, including tyrannosauroids and ornithomimosaurs, were believed to have started their history with feathers. This hypothesis was confirmed in 2004 with the description of the basal tyrannosauroid Dilong, yet another new small theropod from Liaoning (Xu et al. 2004). The early history of tyrannosauroids had long been poorly known, but several primitive forms were described during the first decade of the 21st century. Eotyrannus was named from England in 2001, Guanlong from China in 2006, and a new, English species of StokesosaurusS. clevelandi langhami– in 2008*.

Did I mention Eotyrannus? Here's the newest version of my skeletal recontruction (a few newly recognised elements make it look different from prevously published versions). From the Naish & Cau monograph, to be published some time in 2014.

* Since this text was written, Dilong and Guanlong have been recovered as non-tyrannosauroids in some analyses (Turner et al. 2007). Meanwhile, Stokesosaurus langhami has been given the new name Juratyrant.

Prosauropod progress

Here's the cover of the 2007 volume alluded to in the adjacent text: Barrett & Batten's multi-authored Special Papers in Palaeontology volume Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs.

New theropod discoveries routinely make the headlines due to the popularity of these dinosaurs with the public, but a substantial amount of work on a somewhat less charismatic group of dinosaurs – the basal sauropodomorphs or “prosauropods” – has appeared since 2000. A prosauropod “research renaissance” is in progress, and in 2007 an important, multi-authored volume on this group appeared.

This renaissance involved not only descriptive work, but exciting investigations of dinosaurian biology, growth, and lifestyle. South African Massospondylus embryos, described in 2005, showed that juveniles were fundamentally different from adults (Reisz et al. 2005), and analysis of the forelimb anatomy of Massospondylus and Plateosaurus revealed that these animals could not use their forelimbs in regular walking (Bonnan & Senter 2007), as was thought. A 2005 study on bone growth in Plateosaurus showed that different individuals grew at different rates (Sander & Klein 2005). Some matured quickly, and others grew slowly, at rates comparable to those of living crocodiles.

Sauropod studies

Antetonitrus (from Yates & Kitching 2003), a key taxon in our understanding of sauropod gait and limb evolution. Isn't this also a key taxon in the PhyloCode contributions on Sauropodomorpha? Huh, I guess we'll never know (certainly seems that way, grr). Click to enlarge.

The biology and diversity of the giant sauropodomorphs, the sauropods, with their column-like limbs, also became the focus of renewed palaeobiological work. Questions on the evolution of the unusual limbs and hands of these giant dinosaurs were illuminated by the discovery of primitive forms such as Antetonitrus. Studies on growth rates deduced from the internal structure of bone confirmed that sauropods grew astonishingly quickly (Sander et al. 2004). Particularly interesting new sauropods described during the early 21st century include the giant brachiosaur Sauroposeidon*, the short-necked diplodocoid Brachytrachelopan, and the highly atypical Xenoposeidon, currently known only from a single vertebra fundamentally distinct from those of all other sauropods (Taylor & Naish 2007). New discoveries also showed that titanosaurs, which are traditionally regarded as restricted mainly to the southern continents, also have a good Asian fossil record.

* D’Emic & Foreman (2012) argued that Sauroposeidon ain’t no brachiosaur, but that it’s a somphospondylan instead (Somphospondyli is the titanosauriform clade that includes Euhelopus and titanosaurs). Furthermore, it seems to be synonymous with Paluxysaurus (the latter was named in 2007, versus Sauroposeidon’s 2000), in which case we have a lot more than three neck vertebrae to go on.

The Great Dinosaur Discoveries (Naish 2009) spread on Sauroposeidon... though, no mention of Paluxysaurus of course. Famous boy-in-a-footprint at far right; images from Matt Wedel at left, Acrocanthosaurus by Julius Csotonyi at top right.

For previous Tet Zoo articles on The Great Dinosaur Discoveries and some of the other dinosaur-themed issues mentioned here, see…

Refs – -

Bonnan, M. F. & Senter, P. 2007. Were the basal sauropodomorph dinosaurs Plateosaurus and Massospondylus habitual quadrupeds. Special Papers in Palaeontology 77, 139-155

D’Emic, M. D. & Foreman, B. Z. 2012. The beginning of the sauropod dinosaur hiatus in North America: insights from the Lower Cretaceous Cloverly Formation of Wyoming. Journal of Vertebrate Paleontology 32, 883-902.

Naish, D. 2009. The Great Dinosaur Discoveries. A & C Black, London.

- . & Martill, D. M. 2001. Ornithopod dinosaurs. In Martill, D. M. & Naish, D. (eds) Dinosaurs of the Isle of Wight. The Palaeontological Association (London), pp. 60-132.

Reisz, R. R., Scott, D., Sues, H.-D., Evans, D. C. & Raath, M. A. 2005. Embryos of an Early Jurassic prosauropod dinosaur and their evolutionary significance. Science 309, 761-764.

Sander, P. M. & Klein, N. 2005. Developmental plasticity in the life history of a prosauropod dinosaur. Science 310, 1800-1802.

- ., Klein, N., Buffetaut, E., Cuny, G., Suteethorn, V. & Le Loeuff, J. 2004. Adaptive radiation in sauropod dinosaurs: bone histology indicates rapid evolution of giant body size through acceleration. Organisms, Diversity & Evolution 4, 165-173.

Taylor, M. P. & Naish, D. 2007. An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England. Palaeontology 50, 1547-1564.

Turner, A. H., Pol, D., Clarke, J. A., Erickson, G. M. & Norell, M. A. 2007. A basal dromaeosaurid and size evolution preceding avian flight. Science 317, 1378-1381.

Xu, X., Norell, M. A., Kuang, X., Wang, X., Zhao, Q. & Jia, C. 2004. Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids. Nature 431, 680-684.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com! Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. JDaniel 7:38 pm 07/28/2013

    Anyone know how to get a copy of the Scipionyx monograph? I have tried contacting both the publisher and the authors, but have thus far received no answer. If anyone has current contact info where I can purchase a copy, please let me know.

    Link to this
  2. 2. SciaticPain 9:11 pm 07/28/2013

    Not stoked that Stokeosaurus is now Juratyrant. News to me.

    Link to this
  3. 3. CCollinson 10:02 pm 07/28/2013

    It’s the English species of Stokesosaurus, S. langhami that has been given a new genus; Juratyrant. S. clevelandi is of course the holotype species and therefore will all ways be Stokesosaurus.

    Link to this
  4. 4. JoseD 10:40 pm 07/28/2013

    Sorry I haven’t commented in a while. Glad to see a new blog post about Mesozoic dinos.

    “Back then, we were excited by the possibility that heterodontosaurids might be close to Marginocephalia (yikes, here they’re shown as >part of< Marginocephalia)."

    Based on what I read in Chapter 26 of "The Complete Dinosaur" & under "Phylogenetic inferences" in Sereno 2012, I put my money on heterodontosaurids being either primitive cerapods or primitive ornithopods (I'm more traditional like that).

    "Scipionyx doesn't even get mentioned in The Great Dinosaur Discoveries (hey, nothing personal – it was going to get its own full spread!)."

    All the more reason to write a sequel. ;)

    "South African Massospondylus embryos, described in 2005, showed that juveniles were fundamentally different from adults (Reisz et al. 2005),"

    That paper has reignited my interest in prosauropods, which were much more complex than I originally thought: Not only did Reisz et al. show that prosauropods switched from quadrupedal to bipedal locomotion as they grew up, but confirmed that (as suggested in Moratalla & Powell 1994) they had altricial young; The latter discovery is especially interesting b/c I never expected that in prosauropods of all dinos & it brings up a bunch of new questions (E.g. Did they nest in colonies & regurgitate food for their young like hadrosaurs; How did they switch from altricial to superprecocial young when evolving into sauropods; etc?).

    "Furthermore, it seems to be synonymous with Paluxysaurus, in which case we have a lot more than three neck vertebrae to go on."

    It seems like the identity of the Paluxy River Trackway sauropod changes every time I hear about it: 1st Pleurocoelus, then Sauroposeidon, & now Paluxysaurus.

    Link to this
  5. 5. BrianL 6:41 am 07/29/2013

    If *Dilong* and *Guanlong* aren’t tyrannosauroids, what are they? Also, I’m rather intrigued by a recent paper on South American Cretaceous theropods that concluded that megaraptorans are tyrannosauroids instead of allosauroids.

    Link to this
  6. 6. David Marjanović 6:47 am 07/29/2013

    Here’s the cover of the 2007 volume alluded to in the adjacent text: Barrett & Bassett’s

    It pretty clearly says “Batten” instead of “Bassett” in the picture.

    The Great Dinosaur Discoveries (Naish 2009) spread on Sauroposeidon… I mean, Paluxysaurus.

    Oh no! Sauroposeidon Wedel, Cifelli & Sanders, 2000, has priority over Paluxysaurus Rose, 2007. Fortunately. :-) On Wikipedia, Paluxysaurus redirects to Sauroposeidon.

    Based on what I read in Chapter 26 of “The Complete Dinosaur” & under “Phylogenetic inferences” in Sereno 2012, I put my money on heterodontosaurids being either primitive cerapods or primitive ornithopods (I’m more traditional like that).

    Well, that’s what Sereno used to find 20 years ago, when he cherry-picked the characters for his matrices. Nowadays it looks more like Heterodontosauridae is the sister-group to most or all other ornithischians.

    Link to this
  7. 7. David Marjanović 6:48 am 07/29/2013

    a recent paper on South American Cretaceous theropods that concluded that megaraptorans are tyrannosauroids instead of allosauroids

    I completely missed that! Citation, please!

    Link to this
  8. 8. naishd 7:07 am 07/29/2013

    Wow, evidently I’m doing really well here. If it’s not already obvious, I barely have time to even think at the moment… Will go correct the errors.

    South American workers have published one or two papers where they regard megaraptorans as tyrannosauroids. I don’t think they’re right, but I know that new evidence is forthcoming. There’s a big review paper in Cretaceous Research, if I remember correctly. Will post the citation when I find it.

    Darren

    Link to this
  9. 9. naishd 6:10 am 07/29/2013

    Err, wow… I totally screwed up on Stokesosaurus/Juratyrant and this made it into the book. Dammit.

    Yes, CCollison is correct: the English taxon was originally Stokesaurus langhami, and it’s this that is now Juratyrant. Hey, it’s not like I sometimes work on tyrannosauroids or anything…

    Darren

    Link to this
  10. 10. David_Bressan 7:40 am 07/29/2013

    @JDaniel the Scipionyx monograph should be still available at the natural History Museum of Milan (however they have often much delay in response), it can be ordered 45 Euro + international shipping costs = ca. 60 Euro in total

    Go here.

    Should it really not work out; I maybe (but emphasize on maybe) could organize a second-hand copy

    Link to this
  11. 11. BrianL 9:28 am 07/29/2013

    @David Marjanovic: I’d have thought that you, as a frequent participant in DML discussions would have noticed that paper being linked to by Ben Creisler a few days ago. You can find the abstract here.

    Link to this
  12. 12. LeeB 1 9:14 pm 07/29/2013

    Andrea Cau on the Therapoda blogspot is going to comment on Megaraptora as a member of Tyrannosauroidea soon according to his blog (he posts previews of topics he is going to post on).

    LeeB.

    Link to this
  13. 13. naishd 9:27 pm 07/29/2013

    Huh, wonder where he got that idea from? :)

    Darren

    Link to this
  14. 14. LeeB 1 9:37 pm 07/29/2013

    And fortunately the upturn in studies on dinosaurs recently is also paralleled in some other fields of vertebrate palaeontology; there has been a massive increase in studies of marine reptiles and pterosaurs, and also amongst the mammals some of the pleistocene edentate genera have been getting recent and long overdue revisions.

    LeeB.

    Link to this
  15. 15. David Marjanović 10:11 am 07/30/2013

    I’d have thought that you, as a frequent participant in DML discussions would have noticed that paper being linked to by Ben Creisler a few days ago.

    I’m busy with other stuff, and my inbox is crowded… but still, it’s surprising that I overlooked it. :-) Thanks for the link, I just skimmed and downloaded the paper! Looking forward to Andrea’s post.

    there has been a massive increase in studies of marine reptiles and pterosaurs

    Also temnospondyls, mostly amphibamids, dissorophids, trematopids and now eryopids, and “microsaurs” (Batropetes, potentially important for lissamphibian origins, was redescribed a few weeks ago, with more to come, and new members of the gymnarthrid/ostodolepidid clade keep showing up).

    Link to this
  16. 16. naishd 6:57 pm 07/30/2013

    BrianL (comment # 6) asked…

    “If *Dilong* and *Guanlong* aren’t tyrannosauroids, what are they?”

    Turner et al. (2007) found Dilong to be the sister-taxon to an ornithomimosaur + maniraptoran clade, and hence closer to crown-theropods than are tyrannosauroids proper. Annoyingly, you can only see this in the Supplementary Online Material, which is partly why it’s mostly been missed. A few other researchers/research groups have recovered the same relationship since, however.

    Turner, A. H., Pol, D., Clarke, J. A., Erickson, G. M. & Norell, M. 2007. A basal dromaeosaurid and size evolution preceding avian flight. Science 317, 1378–1381. SOM available for free here.

    Darren

    Link to this
  17. 17. Jenny Islander 8:24 pm 07/30/2013

    Hey, I discovered that my public library has a copy of Feduccia’s Origin and Evolution of Birds. Should I recommend The Inner Bird as a replacement or is there something published since 2007 that would be better?

    Link to this

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