Tetrapod Zoology

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Once again I’m going to recycle an old book review, sorry about that. Have had no internet access at home for the last few days, so things have been difficult here, to say the least (like so many people, I now rely on constant daily internet access for work). Anyway, find below my review of Tidwell & Carpenter’s Thunder-Lizards book. The review was published in 2006 so is now rather dated. I haven’t changed the text, but please note the following; a full technical paper addressing the neck posture stuff discussed below has since been published (Taylor et al. 2009); titanosaurs no longer lack thumb claws entirely, thanks to the Australian lithostrotian Diamantinasaurus, and in fact Diamantinasaurus and Wintonotitan mean that what’s stated below about Australian sauropods is now woefully inaccurate (Hocknull et al. 2009); and the discussion of melanorosaurids given below was written before Yates (2007) published an important analysis where ‘melanorosaurids’ became scattered far and wide across the sauropodomorph tree. The brief comments on the content and phylogenetic definition of Sauropoda are now redundant given the new definition currently in press. Oh, and I do now understand the Stonehenge reference.

Also worth noting while I’m here is that – as you’ll know if you keep tabs on SV-POW! (as I’m sure you do) – the last few weeks have been particularly exciting in the world of sauropod news. We’ve seen the publication of the very neat new taxa Qiaowanlong kangxii and Spinophorosaurus nigerensis, and Mike Taylor has had his Journal of Vertebrate Paleontology paper on the distinction of Giraffatitan from Brachiosaurus published [Taylor's new reconstruction of Brachiosaurus shown below. Unlike him, I don't think that Giraffatitan is such a horrible name]. Anyway, here we go…

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I suppose most people have lost track of how many books Indiana University Press has published on fossil vertebrates as part of its ‘Life of the Past’ series. I have: for reviews of previous volumes, see Palass Newsletter 49: 95-98, 49: 101-103, 50: 91-93, 52: 85-87, 53: 110-112, 56: 128-131, 59: 118-120, 59: 131-132, 60: 79-82 and 60: 90-92 (and that’s not all of them). Continuing their theme of multi-authored volumes dedicated to specific dinosaurian groups, Thunder-Lizards covers (or does it? Read on) the sauropodomorphs: the long-necked sauropods and their relatives. The quality of included papers varies, with some being excellent, well written and highly useful, and others being, well, not so excellent.

The book is divided into four sections. ‘Sauropods old and new’ provides new data on several taxa; ‘Sauropods young to old’ includes contributions on ontogenetic variation; ‘Body parts: morphology and biomechanics’ covers assorted aspects of sauropod anatomy; and ‘The global record of sauropods’ is made up of reviews on geographical assemblages. But while the included contributions are grouped into these sections, in terms of what is and what is not included, there is a random feel, and neither taxonomic nor stratigraphic coverage is equal. It is telling that, while the word ‘sauropodomorph’ features in the title, the word ‘sauropod’ is used in the titles of all of the book’s sections. Of the 21 included papers, only one – Galton et al.’s on Melanorosaurus – focuses on a taxon that has traditionally been regarded as a non-sauropod and, if some current phylogenies are to be accepted (Yates & Kitching 2003), Melanorosaurus is a basal sauropod anyway. So non-sauropod sauropodomorphs – ‘prosauropods’ in traditional parlance – aren’t really featured in the volume at all: it may as well have been titled ‘The Sauropod Dinosaurs’. Why weren’t ‘prosauropods’ represented in this volume? It most likely comes down to the fact that they’ve conventionally been regarded as the most boring (and hence least studied) of dinosaurs. Happily the disdain that ‘prosauropods’ have long received will soon be rectified, in part, by an academic volume presently in preparation, and due to appear in 2007.

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The ‘Sauropods old and new’ section starts with Galton et al. on Melanorosaurus. This paper provides new information on melanorosaurids and, by comparing melanorosaurid characters with synapomorphies taken from various different studies, discusses how these animals might fit within Sauropodomorpha. Unfortunately the article becomes an inconclusive progress report, rather than the definitive redescription it could have been. While these authors use the term ‘prosauropod’ in places, it is sometimes unclear exactly what they mean by this, given that there is more than one interpretation of this term. At its most inclusive, Prosauropoda might be almost as traditionally conceived, but if other phylogenies are favoured, and if Plateosaurus is used as the anchor for Prosauropoda (Sereno 1998), then Prosauropoda is synonymous with Plateosauria [adjacent pic: rarely seen Greg Paul restoration of Riojasaurus, © Greg Paul].

Contributions from John S. McIntosh are always welcome, and the excellent description he provides here of Barosaurus is useful. Thoughts on Tendaguru material are included as is a mention of his once-held idea that Supersaurus was not a distinct genus, but a large Barosaurus [the AMNH Barosaurus mount as we know and love it shown below, photo by Matt Wedel].

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Rather more problematic, however, is Carpenter and Tidwell’s paper on Astrodon from the Aptian-Albian of Maryland. One of their primary arguments is that the name Astrodon johnsoni has priority over Pleurocoelus nanus, and that the latter should be regarded as a synonym. However, they are happy to admit that Astrodon is based on non-diagnostic teeth and I can’t determine how it’s known that the substantial amount of referred material really does belong to the same taxon as the non-diagnostic teeth, as Carpenter and Tidwell assert it does. I am not encouraged by the fact that they switch between the spellings ‘johnsoni‘ and ‘johnstoni‘ throughout the text, that all the characters regarded as diagnostic come from ‘very young’ individuals, nor by the absence of units from the scales that accompany their skeletal reconstruction. Furthermore, while Carpenter and Tidwell regard the vertebral proportions, and extent of pneumatic excavations, of Astrodon as diagnostic for the taxon, a paper elsewhere in the same volume shows that ‘pleurocoel size … appears to decrease in proportion to the total centrum length when compared with that in juvenile animals’ and that ‘neck length increases proportionally to total body length throughout ontogeny’ (Ikejiri et al., p. 173). The section ends with Le Loeuff’s article on Ampelosaurus, an Upper Cretaceous French titanosaur. Given that this taxon is now represented by over 500 bones, including an articulated skeleton that preserves a ‘well-preserved disarticulated skull’ (Le Loeuff, p. 136), the data provided here is, again, a provisional progress report. However, more information is provided on the taxon than has been published before [picture of Camarasaurus below by Vladimir Krb. I quite like some of his stuff. Does anyone know if he's still working? And how the hell do you pronounce his family name?].

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‘Sauropods young to old’ includes Foster’s description of new juvenile Apatosaurus and Camarasaurus specimens, Ikejiri et al. on ontogenetic variation in Camarasaurus, Tidwell et al. on ontogenetic features observed in a Camarasaurus pelvis, and Tidwell and Wilhite on forelimb ontogeny in Venenosaurus. Ikejiri et al.’s paper is particularly good in documenting the substantial amount of variation now known for most parts of the Camarasaurus skeleton. Mostly this is ontogenetic and involves the development of rugosities and extra processes, but there are also indications of sexual dimorphism, and superimposed on all of this is individual variation. The new data provided by Tidwell et al. on Camarasaurus shows that characters conventionally regarded as synapomorphic for some sauropod clades (e.g., six sacral vertebrae and widely flaring ilia) occur elsewhere in the group as individual variations. Sigh: another ‘cautionary note for those working with less well represented taxa’ (Tidwell et al., p. 185). Mostly, the take-home message from the section is a coherent and well-supported one: that sauropod growth is mostly isometric (though with some allometry occurring in the neck). This contrasts with the data from other dinosaur groups, and it’s a good question as to why sauropods were so different.

Included within the morphology and biomechanics section are papers on Camarasaurus neuroanatomy, two on neck posture and function, one on hyposphene-hypantrum articulations, four on the morphology and evolution of the appendicular skeleton, and a review article on stress fractures. The strongest papers in this section are Matthew Bonnan’s excellent, detailed review of foot anatomy and D. Ray Wilhite’s on appendicular bone variation seen in Morrison Formation taxa. Bonnan shows that, far from being the ‘rubber stopper on the end of a crutch’ imagined by some authors, the sauropod foot was morphologically novel and uniquely flexible. Sebastian Apesteguía’s two papers – one on the morphology and evolution of the metacarpus and the other on the hyposphene-hypantrum complex – are also good reviews packed with new information. As if sauropods weren’t strange enough with their columnar metacarpal arcades and reduced (or even absent) manual phalanges, Apesteguía discusses the presence of bowed ‘banana-shaped’ first metacarpals in some titanosaur taxa as well as evidence for a novel soft-tissue covering to the distal ends of the metacarpals. I am left wondering why a small photo of Stonehenge is included in one of Apesteguía’s figures, however.

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It would be an odd sauropodomorph volume indeed that did not focus at least in part on long necks. However, surprisingly little work has been done on this area, and basic questions of neck posture and orientation, and zygapophyseal movement, remain unanswered, despite the reasonable amount of work published on neck motion and orientation in extant tetrapods. Kent Stevens and J. Michael Parrish have published a couple of articles on sauropod neck posture, and, using software dubbed DinoMorph, have applied computer modelling to digitally reconstructed skeletons (Stevens 2002, Stevens & Parrish 1999) [CG diplodocid with inferred limits of neck posture shown here; from Stevens (2002)]. While there seems to be near-universal agreement that diplodocoids had a horizontal neutral neck posture [UPDATE: err, whoops], Stevens and Parrish hold the more controversial point of view that all sauropods were like this, even Camarasaurus and Brachiosaurus. Already their interpretations have been challenged by those arguing that they have not accounted for flexibility within the dorsal vertebrae, that their reconstructed neck postures are no less speculative than the artistic reconstructions they are so critical of, and that their reconstructed necks contain misalignments and disarticulations. Rather than defending or refining the method, this paper is mostly a review of what previous authors have said about the feeding styles and neck mobility inferred for sauropods, and there is little new data or interpretation. Their reconstructed neck postures do not result from virtual modelling, but from ‘using illustrations of the original material’ (p. 217): in other words, drawings from monographs. Overall is it not a convincing approach to the problem. A second contribution on neck posture comes from David Berman and Bruce Rothschild, who used CT x-rays to establish the internal morphology of cervical vertebrae, and from this work out neck posture. Unfortunately the figures they provide are all but useless and may as well be anything.

The last section of the book (‘The global record of sauropods’) reviews sauropods from southern Europe, Patagonia and Australia, with a contribution on trace fossils from India. Fabio Dalla Vecchia’s article reviews and describes sauropod bones and tracks from the Tethyan carbonate platforms of Italy, Slovenia and Croatia, and also includes interpretation of Cretaceous vertebrate palaeobiogeography across the area. While the material is not fantastic, the figures he provides (particularly of vertebrae) are highly detailed. That’s tremendously useful when you have to spend time trying to interpret sauropod vertebrae, and Dalla Vecchia’s figures contrast markedly with rather less satisfactory figures of sauropod vertebrae recently published in another major work on sauropods (Upchurch et al. 2004). Patagonian sauropods are reviewed by Salgado and Coria, and new data on Australian forms is provided by Molnar and Salisbury. It used to be thought that Australia had a particularly poor sauropod record, comprising Rhoetosaurus and Austrosaurus and not much else. In fact the record is far richer than this – ok, it’s not on par with that of North or South America, or Asia, or Europe… or, err, Africa – but it does in fact include multiple specimens, and by specimens I don’t just mean isolated vertebrae. Furthermore, the old view that Australia lacked titanosaurs during the Cretaceous, and was instead home to late-surviving relict taxa, no longer seems supported.

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While previous IUP volumes have been flawless in terms of editing, Thunder-Lizards isn’t up to usual standards. We have specific names spelt incorrectly here and there, or accidentally given capital first letters. A massive shadow, looking suspiciously like that cast by a human holding a camera, looms large in one of several less-than-brilliant field photos. Mostly the figures have reproduced well however, and Todd Marshall’s cover art is brilliant [adjacent image - from one of my talks - shows the late Jim Jensen with (on the left) the holotype Supersaurus scapulocoracoid BYU 5500, and (on the right) the "Ultrasauros" scapulocoracoid BYU 9462].

Overall, IUP have provided us with a volume similar in calibre to the other dinosaur volumes published in the Life of the Past series: sometimes lacking in academic rigour, and indeed flawed in places, but excellent and rewarding in others. The sheer volume of information included means that the articles of highest quality are almost swamped by the others, and for this reason it could be argued that they won’t be as widely read as, or get the accolade and citation, they deserve. So there is novelty, value and excellence in Thunder-Lizards: for this reason this book should be owned by everyone with a serious interest in sauropods. And I do mean sauropods, and not sauropodomorphs.

Virginia Tidwell & Kenneth Carpenter (2005). Thunder-Lizards: the Sauropodomorph Dinosaurs. Indiana University Press, Bloomington and Indianapolis, 495pp. ISBN 0-253-34542-1, $59.95 (hardback).

This book review originally appeared in the Palaeontological Association Newsletter 61: available (for free download) here. It is reproduced with permission.

For previous Tet Zoo articles on sauropodomorphs see…

Refs – -

Hocknull, S. A., White, M. A., Tischler, T. R., Cook, A. G., Calleja, N. D., Sloan, T. & Elliott, D. A. 2009. New Mid-Cretaceous (latest Albian) dinosaurs from Winton, Queensland, Australia. PLoS ONE 4(7): e6190. doi:10.1371/journal.pone.0006190

Sereno, P. C. 1998. A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 20, 41-83.

Stevens, K. A. 2002. DinoMorph: parametric modeling of skeletal structures. Senckenbergiana lethaea 82, 23-34.

- . & Parrish, J. M. 1999. Neck posture and feeding habits of two Jurassic sauropod dinosaurs. Science 284, 798-800.

Taylor, M. P., Wedel, M. J. & Naish, D. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54, 213-220.

Upchurch, P., Barrett, P. M. & Dodson, P. 2004. Sauropoda. In Weishampel, D. B., Dodson, P. & Osmólska, H. (eds) The Dinosauria, Second Edition. University of California Press (Berkeley), pp. 259-322.

Yates, A. M. 2007. Solving a dinosaurian puzzle: the identity of Aliwalia rex Galton. Historical Biology 19, 93-123.

- . & Kitching, J. W. 2003. The earliest known sauropod dinosaur and the first steps towards sauropod locomotion. Proceedings of the Royal Society of London B 270, 1753-1758.

Comments

  1. #1 David Marjanović
    September 16, 2009

    And how the hell do you pronounce his family name?

    Well, you say “k”, then you say “r” (a Spanish one), and then you say “b”. :-|

    No vowel is needed. The r takes over that role, as it commonly does in American English (where there is no “e” in “number”).

  2. #2 Michael P. Taylor
    September 16, 2009

    Shame on you, Dr. Naish, and your Dry Mesa scapulocoracoid-misidentifying ways! The element in the right-hand picture, taken from Dodson (1990) is indeed that of the “Ultrasauros” specimen, but the one shown on the left is of course from Supersaurus. Hang your head, sir!

  3. #3 Darren Naish
    September 16, 2009

    I knew I’d screw up on that. Did a quick check but was obviously not thorough enough – I have a good excuse, I was baby-juggling while publishing that article.

  4. #4 Anonymous
    September 16, 2009

    I suppose the Pleurocoelus-Astrodon issue is now moot, since virtually all “Pleurocoelus” remains in Texas have now been reassigned to a new genus, Paluxysaurus…except for that one in…Wise County is it? Even Carpenter mentions that the “Texas Pleurocoelus” are probably distinct enough to merit their own genus.

    As for Giraffatitan, I don’t think the change is bad at all. While Brachiosaurus is a more evocative name (perhaps due to Jurassic Park and the fact that its the most popular sauropod known by its actual name (I’m looking at you, “Brontosaurus”)), Giraffatitan actually makes sense. Giraffa-titan. Giraffe. Titan. A perfect name for a sauropod that was most likely emulating the modern giraffe in niche. And it was found in Africa too. “Arm lizard” makes a bit of sense if one considers Brachiosaurus’ really long forelimbs, but its still rather weird.

    Darren, have you ever considered that diplodocid sauropods held their necks “between” the swan necked model that you and your fellow co-writers suggest, and the horizontal model suggested in the Digimorph analysis? There were large numbers of diplodocid sauropods running around in the Late Jurassic, almost too many to immediately assume they were all high browsers. In places with decent enough megafaunal assemblages today (again, Africa), there are only a handful of high browsers, and a lot of them also alternate between low and high browsing (elephants). Again, its a bit of a flawed comparison due to the lack of grass on the Jurassic “savannah”, but there would still be lots of low growing plants (cycads, ferns, etc.) Sauropods could have fed most of the time by lowering their necks into a horizontal position and weed whacking the place, but also stretch them up to feed on leaves (lets face it, they needed all the veggies they could get). When travelling or not eating, their necks could be held out at a lazy upwards angle, allowing them to keep an eye on their surroundings.

    Of course, the Digimorph assumption that the macronarians had horizontal necks is just right out the window. The way that Brachiosaurus’ neck exist the body for one just screams high browser.

  5. #5 gray Stanback
    September 16, 2009

    What sauropod is that on the cover?

  6. #6 Anonymous
    September 16, 2009

    I think its supposed to be Paralititan.

  7. #7 Sebastian Marquez
    September 16, 2009

    Yes it is a Paralititan, it’s one of Todd Marshall’s pieces

  8. #8 Sebastian Marquez
    September 16, 2009

    Ack, cut off the second part by accident:

    I always thought his take on sauropods was cool, its so different from a lot of other reconstructions. Does anyone happen to know if there is any specific inspiration for it?

  9. #9 M. O. Erickson
    September 16, 2009

    “Oh, and I do now understand the Stonehenge reference.”

    Dat’s cool. I still don’t!

    “I’m looking at you, ‘Brontosaurus’”

    Okay, this Apatosaurus vs. Brontosaurus thing has gotten so far out of hand I could scream. Diplodocus and Barosaurus are ALWAYS kept as seperate genera, and Apatosaurus and Brontosaurus are almost always kept synonomized, this despite the fact that Apatosaurus ajax and “Apatosaurusexcelsus are as distinct from one another as are Diplodocus and Barosaurus. Where is the logic in that? Having looked for SOME sort of logic in it, I can say that I don’t think there is any to be found.

    Marsh was right. Riggs was wrong. End of story. Or at least in my book it is.

    Phew, done ranting now :)

  10. #10 Anonymous
    September 16, 2009

    I heard at the Field Museum that the primary difference between A. excelsus and A. ajax are the number of sacral vertebrate. And that the difference is more chalked up to age, or else very minor. Not to mention Brontosaurus in paleontological parlance would be considered a chimera (that is, unless Marsh designated a bone that can be definitively proven to belong to Apatosaurus excelsus, rather than the whole skeleton).

    I have also read that Barosaurus had big differences in the construction of its neck vertebrae, as well as there being longer and more of them. And as our fellow SV-POW workers lurking around here will know, the vertebrae are some of the most important diagnostic parts on a sauropod.

  11. #11 M. O. Erickson
    September 17, 2009

    “I heard at the Field Museum that the primary difference between A. excelsus and A. ajax are the number of sacral vertebrate.”

    The overall body proportions are different as well. For the sake of illustration, compare:

    http://www.skeletaldrawing.com/sauropods/apatosaurus_excelsus.png

    and

    http://www.skeletaldrawing.com/sauropods/Apatosaurus_ajax_small.jpg

    “Not to mention Brontosaurus in paleontological parlance would be considered a chimera”

    This is actually just a myth. The fact that Marsh restored the headless skeleton of Brontosaurus with the wrong skull (a partial skull Carpenter and Tidwell later realized belonged to Brachiosaurus) has nothing to do with the confusion of the names. As a side note, T. rex was also originally restored with the wrong head (the incomplete type skull was modelled heavily and incorrectly in plaster after Allosaurus). It happens a lot.

    “I have also read that Barosaurus had big differences in the construction of its neck vertebrae, as well as there being longer and more of them.”

    Yes, that’s one of the major reasons Barasaurus is always considered to be distinct from Diplodocus. My point was that Apatosaurus and Brontosaurus are nearly as distinct from each other as are Diplodocus and Barosaurus, so keeping them in the same genus makes little sense to me. For the moment, I’m keeping them seperate.

  12. #12 LeeB
    September 17, 2009

    If you are going to consider A. ajax as Apatosaurus and A. excelsus as Brontosaurus then what genus/genera are you going to put A. louisae and A. parvus in?

    LeeB.

  13. #13 M. O. Erickson
    September 17, 2009

    “If you are going to consider A. ajax as Apatosaurus and A. excelsus as Brontosaurus then what genus/genera are you going to put A. louisae and A. parvus in?”

    Apatosaurus louisae would be placed in Brontosaurus as Brontosaurus louisae. As I havn’t been able to take a look at A. parvus, I don’t know about that one.

  14. #14 LeeB
    September 17, 2009

    Unfortunately, the paper that re-instated A. parvus had a cladogram that showed that A. louisae is not closer to A. excelsus than A. ajax.

    So A. louisae would probably require its own genus, as if it was retained in Apatosaurus with A. ajax and A. excelsus was put in Brontosaurus then Apatosaurus would be paraphyletic.

    And A. parvus is shown to be close to A. excelsus and another un-named taxon represented by one specimen.

    This is the problem with a simple Apatosaurus/Brontosaurus dichotomy, there are at least four taxa involved.

    Incidentally the Apatosaurus monograph is online and makes interesting reading.

    LeeB.

  15. #15 M. O. Erickson
    September 17, 2009

    “Unfortunately, the paper that re-instated A. parvus had a cladogram that showed that A. louisae is not closer to A. excelsus than A. ajax.”

    A cladogram is just a hypothesis. The hypothesis may well be correct, but it doesn’t “prove” anything beyond reasonable doubt – especially if it conficts with the actual anatomy of the animals, as many cladograms being produced these days do (this is a general observation, not nessacerally targeting the cladogram in question).

    According to McIntosh (1990), there are only three characters that distinguish louisae from excelsus: Anterior extension of the cervical ribs (present in excelsus, absent from louisae); An accessory lamina that subdivides the infrapostzygapophysial cavity of the mid- and posterior cervicals (present in excelsus, absent from louisae); extremely robust femur in louisae. The first one can be ignored because the shape of the cervical ribs can and does vary within a single species. Thus we are left with only two characters that distinguish excelsus and louisae, which is why I feel that louisae would belong in Brontosaurus were Apatosaurus and Brontosaurus broken up. In addition, in overall body proportions excelsus and louisae are far more similar to each other than either is to ajax.

    If the author’s phylogenetic hypothesis that A. parvus is closest to excelsus is correct, then parvus would go into Brontosaurus as well.

  16. #16 David Marjanović
    September 17, 2009

    especially if it conficts with the actual anatomy of the animals, as many cladograms being produced these days do

    Details, please. Which characters are missing from the matrix?

    nessacerally

    Necessarily :o)

  17. #17 M. O. Erickson
    September 17, 2009

    “Details, please. Which characters are missing from the matrix?”

    As I said, it was a general observation, not intended toward the cladogram in the Apatosaurus monograph.

    “Necessarily :o)”

    Typographical error :o)

  18. #18 LeeB
    September 17, 2009

    There may be more characters in the Apatosaurus monograph that separate A. louisae and A. excelsus from each other.
    After all it post dates McIntosh’s paper and was based on a study of all the relevant species.

    LeeB.

  19. #19 M. O. Erickson
    September 17, 2009

    Because I cannot locate the Apatosaurus monograph (you claim it is online, where at?), I can’t say if those authors have more characters that seperate excelsus from louisae. But judging from the anatomical data I have at the moment, I feel that louisae is closer to excelsus than either are to ajax, and both are distinct enough from ajax to warrent a genus of their own (possibly along with A. parvus): Brontosaurus.

    But regardless of the placement of louisae (and parvus for that matter), as of right now I am certain that “Apatosaurusexcelsus is sufficiantly distinct from A. ajax that ressurection of the genus Brontosaurus for the former species is justified.

  20. #20 LeeB
    September 18, 2009

    THe wikipedia article on Apatosaurus has a note 7 at the bottom which has a link to the page where you can download the paper.
    Or try
    http://ci.nii.ac.jp/naid/110004665753/

    which should take you to the same page.
    There is a button there to click to down load the pdf.

    It worked when I tried it a few months back, but was fairly slow to download, it is a reasonably big file.

    LeeB.

  21. #21 David Marjanović
    September 18, 2009

    As I said, it was a general observation, not intended toward the cladogram in the Apatosaurus monograph.

    If you haven’t read at least the character list, how can you know whether any particular cladogram contradicts the morphology? Maybe it just has a more comprehensive sampling of morphology than your head does?

    This is not a rhetorical question, though. Even large cladograms often lack several potentially useful characters (let alone taxa). So it’s entirely possible that you’re right and the cladogram is wrong. Just, please, show us that this is actually the case. Be careful not to develop an argument from personal incredulity (“I can’t believe it, so it’s wrong”).

  22. #22 LeeB
    September 18, 2009

    Regarding the characters that distinguish A. louisae from A. excelsus; I just did some counting of characters in the matrix in the Apatosaurus monograph.
    Of 32 characters listed only 18 were scorable for A. excelsus.
    Of those 12 were different for A. louisae compared to A. excelsus.
    Interestingly only 3 differentiated A. ajax from A. excelsus; although this may be because the A. excelsus specimens had a lot of missing data.

    LeeB.

  23. #23 Dennis D'Asaro
    September 29, 2009

    Probably old business by now, but here is info on one Vladimir Krb.
    http://www.canpages.ca/page/resident/AB/drumheller/vladimir-krb/130571474.html

  24. #24 Concrete Cam
    February 7, 2011

    Thunder Lizards looks like a great book that would thrill dinosaur enthusiasts. The front cover illustration does a great job at depicting their huge size and the weight that would be behind a single footstep. It would be tough to have any roadways or concrete contractors with those dinosaur feet tromping around.

  25. #25 Building Contractors
    March 3, 2011

    This looks like a great book that could provide some good material for bedtime stories. The idea of a dinosaur large enough to step on a roof or garage would make some exciting material for young dinosaur enthusiasts. Much more intriguing in many ways than Clifford the big red dog.