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Is there a finish line? (and how to get there)

September 12, 2012 14 comments

Yes. . .I hope there is a finish line. As with many things started with the best of intentions, the ODP (and its heads – particularly me) has gotten waylaid. That said, it would be a shame to let the numerous contributions and hours of volunteer effort go to waste. So, Matt and Mike and I have been having some serious conversations about finishing this once and for all! So, here’s the deal.

  • I want to finish this. You want to finish this. It just needs to be finished.
  • Analysis and write-up are the main things that need to be done. It requires a bit of concentrated effort (primarily on my part).
  • The way I see it, the most productive product of the analysis would be to examine limb disparity in ornithischian dinosaurs through time. This would entail binning the dinos and running the analysis. Riffing off of recent work by numerous authors, this would involve running a PCO (principal coordinates analysis) on the measurements for each bin. This can then be converted to a metric that shows overall morphological disparity. The primary question this asks is, “How did ornithischians diversify in their limb bone proportions through time?” Was it something that happened right away? Or something that happened later? A related question concerns how to accommodate phylogeny. As with many recent papers, the main thing we’re interested in here are ghost lineages. Given the incomplete nature of the fossil record, ancestral state reconstruction of some sort is probably needed. The problem, however, is that these methods are often. . .vague. . .at best. Perhaps maximum likelihood reconstruction in the relevant R packages? (see this link for an example ) Or perhaps skip trying to reconstruct stuff altogether and take the results with appropriate caution?
  • I envision three analyses: all limbs together (for all animals that are appropriately complete), forelimbs, and hind limbs. This would help account for animals that preserve only forelimbs, or only hind limbs.

Tasks to do:

Timeline:

  • Realistically, upcoming major events in the real world mean that I (Andy) have to get this thing off my plate by December 1 at latest. This is also best for Matt and Mike, too (and everyone, right?). This means a finished, submitted manuscript.
  • If the December 1 thing doesn’t happen, realistically we need a way to “cut the data loose.” Although we’ve had a general statement on the blog that we would rather others hold off on using our data until the paper is published, it isn’t fair to sit on the data for years at a time. So, this means that we would step aside from right of first refusal for publication with the data. This means that others are welcome to use the data without explicit permission (although the ODP should still be cited as the data source). The data would be archived at figshare, which provides a stable link, long-term archiving, and DOI for future linking.

The last of what we need

February 3, 2012 1 comment

Well, this is awkward. Once again we’ve let things lie fallow for far, far too long. We all (= Andy, Mike, and I) feel rotten about it, but more importantly, we now have a finite list of stuff that we need to finish the data haul, and then we can finally do the analyses, write the paper, and generally make good on everything we set out to do.

So rather than waste your time with more blather, here’s the tail end of the wish list:

References That Have Data That Need to be Entered a First Time [note – some may not have measurements, but should at least be checked; I don’t have easy access to all papers]

Bell, PR, Evans, DC (2010) Revision of the status of Saurolophus (Hadrosauridae) from California, USA. Canadian Journal of Earth Sciences 47, 1417-1426.

Butler RJ, Liyong J, Jun C, Godefroit P (2011) The postcranial osteology and phylogenetic position of the small ornithischian dinosaur Changchunsaurus parvus from the Quantou Formation (Cretaceous: Aptian–Cenomanian) of Jilin Province, north-eastern China. Palaeontology 54:667-683.

McDonald, A. T., Barrett, P. M. and Chapman, S. D., 2010. A new basal iguanodont (Dinosauria: Ornithischia) from the Wealden (Lower Cretaceous) of England. Zootaxa, 2569, 1-43.

Prieto-Marquez A. Cranial and appendicular ontogeny of Bactrosaurus johnsoni, a hadrosauroid dinosaur from the Late Cretaceous of northern China. Palaeontology (in press). DOI: 10.1111/j.1475-4983.2011.01053.x

References For Data In Need of Cross-Checking

Cuthbertson, R. S. and Holmes, R. B., 2010. The first complete description of the holotype of Brachylophosaurus canadensis Sternberg, 1953 (Dinosauria: Hadrosauridae) with comments on intraspecific variation. Zoological Journal of the Linnean Society, 159, 373-397.

Ezcurra, M. D., 2010. A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Argentina: a reassessment of dinosaur origin and phylogeny. Journal of Systematic Palaeontology, 8, 371-425.

Godefroit P, Pereda Suberbiola X, Li H, Dong Z-M (1999) A new species of the ankylosaurid dinosaur Pinacosaurus from the Late Cretaceous of Inner Mongolia (P.R. China). Bulletin de l’Institut Royal des Sciences Naturelles de Belgique 69-Supp. B: 17-36.

Huene Fv (1926) Vollständige Osteologie eines Plateosauriden aus dem Schwäbischen Keuper. Geologische und Palaeontologische Abhandlungen (N. F.) 15 (2): 139-179

Longrich, NR (2011) Titanoceratops ouranos, a giant horned dinosaur from the late Campanian of New Mexico. Cretaceous Research 32: 264-276.

Martinez, R. N., Sereno, P. C., Alcober, O. A., Colombi, C. E., Renne, P. R., Montanez, I. P. and Currie, B. S., 2011. A basal dinosaur from the dawn of the dinosaur era in southwestern Pangaea. Science, 331, 206-210.

McDonald AT, Kirkland JI, DeBlieux DD, Madsen SK, Cavin J, et al. (2010) New basal iguanodonts from the Cedar Mountain Formation of Utah and the evolution of thumb-spiked dinosaurs. PLoS ONE 5(11): e14075. doi:10.1371/journal.pone.0014075

Pereda-Suberbiola J, Ruíz-Omeñaca JI, Ullastre J, Masriera A (2003) Primera cita de un dinosaurio hadrosaurio en el Cretácico Superior del Prepirineo oriental (Peguera, provincia de Barcelona). Geogaceta 34: 195-198

Riabinin ANN (1945) [Dinosaurian remains from the Upper Cretaceous of the Crimea] (in Russian). Vsesoy. Nauch.-Issledov. Geol. Inst. Matl. Paleontol. Strat. 4: 4–10.

Ryabinin AN (1939) The Upper Cretaceous vertebrate fauna of South Kazakhstan, Reptilia; Part 1, the Ornithischia. Transactions of the Central Geological and Prospecting Institute 118: 1-38.

Wang X, Pan R, Butler RJ, Barrett PM. 2011 (for 2010). The postcranial skeleton of the iguanodontian ornithopod Jinzhousaurus yangi from the Lower Cretaceous Yixian Formation of western Liaoning, China. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 101: 135-159.

Zhao X, Li D, Han G, Zhao H, Liu F, Li L, Fang X (2007) Zhuchengosaurus maximus from Shandong Province. Acta Geoscientica Sinica 28: 111-122.

Filling in the Blanks

June 22, 2011 7 comments

During the extended gestation/hibernation/dormancy of the ODP, a few new papers with relevant data have slipped into circulation, some with ornithischians preserving limb bones, as well as new or updated phylogenetic analyses. So, if you’re looking for a final chance at data entry, here are a few possibilities:

Open Access

Currie PJ, Badamgarav D, Koppelhus EB, Sissons R, Vickaryous. Hands, feet and behaviour in Pinacosaurus (Dinosauria: Ankylosauridae). Acta Palaeontologica Polonica in press. doi:10.4202/app.2010.0055 [link]

McDonald AT, Kirkland JI, DeBlieux DD, Madsen SK, Cavin J, et al. (2010) New basal iguanodonts from the Cedar Mountain Formation of Utah and the evolution of thumb-spiked dinosaurs. PLoS ONE 5(11): e14075. doi:10.1371/journal.pone.0014075 [link]

Closed Access

Bell, P. R. and Evans, D. C., 2010. Revision of the status of Saurolophus (Hadrosauridae) from California, USA. Canadian Journal of Earth Sciences, 47, 1417-1426.

Butler RJ, Liyong J, Jun C, Godefroit P (2011) The postcranial osteology and phylogenetic position of the small ornithischian dinosaur Changchunsaurus parvus from the Quantou Formation (Cretaceous: Aptian–Cenomanian) of Jilin Province, north-eastern China. Palaeontology 54:667-683. [link]

Cuthbertson, R. S. and Holmes, R. B., 2010. The first complete description of the holotype of Brachylophosaurus canadensis Sternberg, 1953 (Dinosauria: Hadrosauridae) with comments on intraspecific variation. Zoological Journal of the Linnean Society, 159, 373-397.

Ezcurra, M. D., 2010. A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Argentina: a reassessment of dinosaur origin and phylogeny. Journal of Systematic Palaeontology, 8, 371-425.

Langer, M. C., Bittencourt, J. S. and Schultz, C. L., 2011. A reassessment of the basal dinosaur Guaibasaurus candelariensis, from the Late Triassic Caturrita Formation of south Brazil. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 101, 301-332.

Lee, Yuong-Nam; Ryan, Michael J.; and Kobayashi, Yoshitsugo (2011). “The first ceratopsian dinosaur from South Korea”. Naturwissenschaften 98 (1): 39–49.

McDonald, A. T., Barrett, P. M. and Chapman, S. D., 2010. A new basal iguanodont (Dinosauria: Ornithischia) from the Wealden (Lower Cretaceous) of England. Zootaxa, 2569, 1-43.

Makovicky, P. J., Kilbourne, B. M., Sadleir, R. W. and Norell, M. A., 2011. A new basal ornithopod (Dinosauria, Ornithischia) from the Late Cretaceous of Mongolia. Journal of Vertebrate Paleontology, 31, 626-640.

Martinez, R. N., Sereno, P. C., Alcober, O. A., Colombi, C. E., Renne, P. R., Montanez, I. P. and Currie, B. S., 2011. A basal dinosaur from the dawn of the dinosaur era in southwestern Pangaea. Science, 331, 206-210.

Pol, D.; Rauhut, O.W.M.; and Becerra, M. (2011). “A Middle Jurassic heterodontosaurid dinosaur from Patagonia and the evolution of heterodontosaurids”. Naturwissenschaften 98 (5): 369–379. [phylogeny only – no useful postcrania] [link to free PDF]

Prieto-Marquez A. Cranial and appendicular ontogeny of Bactrosaurus johnsoni, a hadrosauroid dinosaur from the Late Cretaceous of northern China. Palaeontology (in press). DOI: 10.1111/j.1475-4983.2011.01053.x [link]

Prieto-Marquez, A. and Salinas, G. C., 2010. A re-evaluation of Secernosaurus koerneri and Kritosaurus australis (Dinosauria, Hadrosauridae) from the Late Cretaceous of Argentina. Journal of Vertebrate Paleontology, 30, 813-837. [no measurements; phylogeny only]

Wang X, Pan R, Butler RJ, Barrett PM. 2011 (for 2010). The postcranial skeleton of the iguanodontian ornithopod Jinzhousaurus yangi from the Lower Cretaceous Yixian Formation of western Liaoning, China. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 101: 135-159.

Note: Most of these citations were gathered from Graeme Lloyd’s excellent compendium of dinosaur phylogenies. I’ve tracked down the links in a few cases, but otherwise you should be able to find them using a quick search on-line. Not all of the papers necessarily have usable data; the list here is a quick-and-dirty overview. I may have missed some important new contributions, too. Please feel free to flag them in the comments, and I’ll add them to the list.

Wondering what to do in order to contribute data, or just need a refresher? Check out this how-to guide.

Categories: To-Do List

Disparity Notebook

June 21, 2011 1 comment

Local disparity guru and paleontologist Randy Irmis (that’s Randall B. Irmis, Ph.D., if you go by his web page) recently posted a nice long list of recommended readings on the issue of disparity – what it is, how to calculate it, etc. As a reminder, disparity is the measure of how different species are from each other in terms of shape, size, or other discrete features (not the same as diversity, which just counts how many different species exist – once again, see Randy’s eloquent post on the topics). It just so happens that documenting disparity in ornithischian dinosaurs is at the top of our list for the ODP. Hence, I decided to buckle down and read through an important recent paper on the topic (one that Randy happened to highlight in his list, too).

In the interest of getting this post out in a timely manner, I’m mainly going to be posting my unpolished notes, taken a few weeks ago in the comfort of my bed (nothing like a little light bedtime reading). I’ve made a few adjustments here and there, but otherwise you can consider this a peek into my stream of consciousness while reading the literature. Because I was mainly interested in how the work could be applied to the ODP, I didn’t really bother with summarizing the specific analyses done by the authors. Thus, without further preface:

The Citation:
Brusatte, S. L., Montanari, S., Yi, H.-Y, and Norell, M. A. 2011. Phylogenetic corrections for morphological disparity analysis: new methodology and case studies. Paleobiology 37: 1-22. [unfortunately, not openly available as a PDF] [link to abstract]

The Main Gist:
The fossil record just isn’t complete – and that’s particularly true for many of the early members of important ornithischian clades (like thyreophorans and marginocephalians). However, it’d be nice to interpolate some of these missing data in order to produce a more complete picture of the changes in a clade’s disparity over time and in morphospace (the multi-dimensional plot of the shape of an animal’s bones, in this case). Brusatte and colleagues, building on the work of many other authors, have formalized a method to fill in some of these gaps by producing a plausible reconstruction of missing ancestors.

Scutellosaurus

An early thyreophoran, Scelidosaurus; image by Nobu Tamura, used under a Creative Commons License

My Notes
[as presented here, it’s a mix of to-do tasks for the ODP, a cookbook for the analysis, and how Brusatte et al.’s method will be applied; caveat emptor]

The questions: What is the morphospace occupied by ornithischian dinosaurs over time? How does the morphospace change? How does the morphospace occupied by specific clades differ?

The tasks:

  • Assemble data matrix (taxon/measurement matrix)
  • Reconstruct ancestoral measurements following Brusatte et al. 2011
  • Calculate Euclidean distance matrix (“quantifies the pairwise dissimilarity between taxa”) – this presumably calculates dissimilarity for each taxon/measurement pair
  • Apply principal coordinates analysis (PCoA) to each analysis (better handles missing data than does PCA [principal components analysis]). Can be done in R.
  • PCoA produces scores for each taxon along n=#taxa axes. Can be done in R.
  • Examine slope of scree plot to determine where break occurs; only examine these “interesting” axes. I think this scree plot can be done in R.
  • Calculate disparity indices from the PCoAs, using different bins (categories). Can be done in R. Categories might include: 1) clade; 2) time; 3) locomotor category; 4) combination of clade/locomotor category.
  • Indices include: sum of range of values along axis 1, 2, … n (i.e., range 1+range2+range3. . .); product of range of values along axis 1, 2, n (range 1 * range 2 * range 3. . .) normalized to the nth root; and same sum and products for variance in each bin.
  • Rinse and repeat using ancestral values as calculated following Brusatte et al. 2011.

Ideal results:

  • Disparity indices that can be compared statistically (using bootstrap values) for various categories. E.g., a disparity value for Ceratopsia, Ornithopoda, Thyreophora, etc. disparity  value for quadrupeds vs. bipeds.
  • Graphs showing point clouds for various clades along various axes (e.g., PC1 vs. PC2)
  • Graphs showing trends for disparity over time, with different groups. E.g., trend line showing disparity in ornithischians as a whole, along with trend line showing disparity in thyreophorans, ceratopsians, etc. Potential sample size issues here, particularly for clades with few members or few members early in their history
  • Narrative text and / or table showing what factors are loaded on which axes

Summertime, open ignorance, and finishing the project

May 25, 2011 7 comments

Hi, all. Thanks for your patience this spring. Sorry we’ve let things lie fallow for so long. Many thanks to everyone for keeping things ticking over while we were AWOL.

Like Andy said in the last post, it’s time to wrestle this thing to the ground and stick a knife through its heart (I may be paraphrasing a bit). Andy, Mike, and I have cleared some protected time in our summer schedules to finish the analyses and write the paper. The next two weeks may be a bit quiet on our end as we all work to get other things tied up and off our desks–and as Andy moves his residence!–but we should be ready to hit it hard by the second week of June.

There is a lot of work to be done, and there are lots of ways to contribute to the paper for everyone who wants to be involved, right now and continuing through the summer. I’ll give some suggestions in a minute. But first, an admission.

We don’t really know what we’re doing here. That’s obvious with the social side of the project, because nothing like this has been attempted before, at least not on this scale or with this degree of openness. But it’s also true on the scientific side. None of us (Andy, Mike, or I) has ever written a paper on this topic. There are some specific analyses that we need for the paper that we’ve never run before. So we are very much learning as we go–this is the open ignorance I alluded to in the title. This isn’t by accident. We could have chosen to do something simpler and less ambitious–perhaps repeat a project that we’d already done before with only the names of the critters changed. But we wanted to learn from the project–from you, the contributors, and alongside you–and to grow as scientists from having participated in it. And we want the final product to be a truly collaborative effort, and not to simply walk everyone through a series of moves that we already know by heart.

And it is working. We have been amazed at the level of enthusiasm and commitment that you have brought to the project, and our only regret is that we have not reciprocated with the sustained level of effort that you, and the project, deserve. So we’re committing ourselves to getting this done, starting now.

How can you contribute? Here are some suggestions:

  • Update the database. New taxa continue to be described, new descriptions of established taxa continue to be published, and older publications continue to become available. So if you have been wanting to do some (more) good old-fashioned ODP gruntwork, there’s still a little time.
  • Suggest relevant references, or read up on the ones that are already suggested. It might be a good idea to gather those references together so they can be made available to anyone who is working on the project. We’ll probably do a post specifically on this in the near future, but there’s no reason not to be pulling things together in the meantime.
  • Look at the outline of the paper, suggest improvements, and–if you are so inclined–start writing those bits that can be written right now. For now, feel free to post chunks in comments or send them to us. Jay Fitzsimmons’s paragraph on citizen science and the ODP is a good model to follow. We’ll definitely be posting more on the actual writing of the paper soon, but, as with boning up on the relevant references, there’s no reason to hold off if this is something you’re interested in working on.
  • Analyze data. Obviously there are limits to what we can do until we really finalize the database once and for all, but this is a good time for exploring the data and for test-driving analyses to be done on the finalized database. We have enough data that overall trends are not likely to change much, so anything that looks interesting now will probably still be interesting in the final version.
  • Work on a time-calibrated phylogeny for the dataset. This is a big one, again probably deserving of a post of its own. We’ll also need to update the “master tree” to include the most current phylogenetic trees for the included taxa. If you’re into trees, timelines, or both, the mothership is calling you home.
  • Figure out how to do disparity analyses. This is one of those things that we project organizers have never done before. We’re reading up on it right now, but if you know anything about it, let us know. Even when we get up to speed, we’ll still need your input. Like Project Mayhem, you can determine your own level of involvement.
  • Other stuff? The project is probably at its maximum breadth in terms of types of work to be done. Up until now we’ve focused mainly on building the database and outlining where we want to go, and in a few weeks we’ll have the database finalized and our efforts will narrow as we focus on running the analyses and writing the paper. So whether you’re brand new and want to get involved for the first time, or an old hand who wants to do something different, there is something around here that needs doing. Have a look at the tasks list, go back through the last few posts, and see what appeals to you. If in doubt, give us a shout.

That’s all for now. Stay tuned for more posts very soon. But don’t just stay tuned–keep posting ideas, data, references, bits of text, and whatever else you want to contribute. We’ll do likewise.

Categories: Housekeeping, To-Do List

Outlining the Paper

December 3, 2010 13 comments

Pisanosaurus, by FunkMonk

After all of this work and data accumulation, it’s probably just about time to do the darned analyses and write the darned paper. We’ve had quite a bit of discussion over the last year or so on what this might look like. To that end, I want to outline one possibility and then solicit input from everyone. Again, this is very much a work in progress, so please comment as appropriate.

Working Title: Trends and Variation in Limb Proportions of Ornithischian Dinosaurs [please think up a more exciting, succinct, and descriptive title]

Outline of Contents

  1. Introduction
    What are ornithischian dinosaurs?
    What do we already know about their modes of locomotion and limb proportions? How are they unusual compared to other dinosaurs?
    What have other workers done with analyzing dinosaurian limb proportions?
    What is the main point of this study? [to document, describe, and interpret ornithischian limb morphology, and how it relates to function]
  2. Materials and Methods
    Jay Fitzsimmon’s very nice paragraph on citizen science and the ODP goes here.
    How specimens were selected.
    Where we got the measurements.
    How we winnowed down the data.
    How we assembled the phylogeny
    Statistical analyses performed on the data [PCA to describe overall patterns; regressions accounting for phylogeny to describe various allometric patterns {we probably only want to look at patterns that are comparable with theropods or other analyses of interest}; analyses looking at trends within clades; analysis of disparity; analysis comparing characters using phylogenetically independent contrasts]
  3. Results
    Principal components analysis – done on uncorrected data, how do we describe the limb proportions in various ornithischians. Believe it or not, this hasn’t really been done!
    Regressions accounting for phylogeny to describe allometric patterns – we might want to look at a few regressions, such as forelimb vs. hindlimb length, femur vs. tibia+MTIII, humerus vs. radius+MCIII
    Analysis documenting trends in clades –  include pretty colored images a la Padian et al’s charts of dinosaurian growth rates
    Analysis of disparity – how disparate are various groups? How rapidly did the bauplans for the various groups develop?
  4. Discussion & Conclusions
    What do these results mean?
    We’ll have more to fill in when we get some “final” results!

A Recommendation:

We all will have an urge to make this paper as absolutely comprehensive as possible – in the past we have talked about many, many different kinds of analyses, hypotheses, etc. But, I think we also want to avoid getting bogged down in needless detail or bloated and waylaid by side tangents of marginal importance. (some of what I outlined above may very well fall into this category!) So, let’s keep that in mind. . .(but don’t be afraid to make suggestions, either!)

Relevant References for the ODP

November 15, 2010 22 comments
Scelidosaurus

Olde Timey Restoration of Scelidosaurus, after Marsh

In response to a recent query on this blog, ODPer Christian Foth contributed a list of papers potentially relevant to the ODP, specifically limb posture and evolution in ornithischian dinosaurs. It’s important to recognize work that others did before and see how it relates to ours. Furthermore, a good reference list is essential for the upcoming manuscript.

What can you do?

If you think of another paper that might be added to the list (within reason, of course), drop a line in the comments section. If you are interested in providing a summary of a certain paper as a guest blog post (either here or at your own blog), that would be great, too. As always, one need not be a Ph.D’ed scientist to apply! We’re just looking for a short summary.

For my part, I added the Middleton and Gatesy reference – although it deals with theropods, I think some of the background info and analytical methods are quite relevant. Hmm. . .that might be a good one to blog about.

Reference List in Progress

Alexander R. 1985. Mechanics of posture and gait of some large dinosaurs. Zoological Journal of the Linnean Society 83: 1-25.
Bakker RT. 1968. The superiority of dinosaurs. Discovery 3 (2): 11-22.
Biewener (1983). Allometry of quadrupedal locomotion: the scaling of duty factor, bone curvature and limb orientation to body size. J. Exp. Biol. 105: 147-171.
Bonnan MF & P Senter. 2007. Were the basal sauropodomorph dinosaurs Plateosaurus and Massospondylus habitual quadropeds. Special Papers in Palaeontology 77: 139–155
Bonnan, MF, & AM Yates. 2007. A new description of the forelimb of the basal sauropodomorph Melanorosaurus: implications for the evolution of pronation, manus shape and quadrupedalism in sauropod dinosaurs. pp. 157-168 in: Paul M. Barrett and David J. Batten (eds.), Special Papers in Palaeontology 77: Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs. The Palaeontological Association, U.K.
Bultynck P (1992) An assessment of posture and gait in Iguanodon bernissartensis Boulenger, 1881. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique: Sciences de la Terre 63: 5-11.
Carrano MT. 2000. Homoplasy and the evolution of dinosaur locomotion. Paleobiology 26 (3): 489-512.
Carrano MT (2001) Implications of limb bone scaling, curvature and eccentricity in mammals and non-avian dinosaurs. Journal of Zoology 254: 41-55.
Dilkes DW. 2000. Appendicular myology of the hadrosaurian dinosaur Maiasaura peeblesorum from the Late Cretaceous (Campanian) of Montana. Transactions of the Royal Society of Edinburgh, Earth Sciences 90: 87-125.
Dilkes DW. 2001. An ontogenetic perspective on locomotion in the Late Cretaceous dinosaur Maiasaura peeblesorum (Ornithischia: Hadrosauridae). Canadian Journal of Earth Sciences 38: 1205-1227.
Dodson, P & JO Farlow. 1997. The forelimb carriage of ceratopsid dinosaurs. DinoFest International Proceedings 393-398.
Galton PM. 1970. The posture of hadrosaurian dinosaurs. Journal of Paleontology 44 (3): 464-473.
Garstka WR & DA Burnham. 1997. Posture and stance of Triceratops. Evidence of digitigrade manus and cantilever vertebral column. DinoFest International Proceedings 385-391.
Heinrich DE, Bruff CB & DB Weishampel. 1993. Femoral ontogeny and locomotor biomechanics of Dryosaurus lettowvorbecki (Dinosauria, Iguanodontia). Zoological Journal of the Linnean Society 108: 179-196.
Hutchinson JR. 2004. Biomechanical modeling and sensitivity analysis of bipedal running ability. I. Extant taxa. Journal of Morphology 262: 421-440.
Johnson RE, Ostrom JH (1995) The forelimb of Torosaurus and an analysis of the posture and gait of ceratopsian dinosaurs. In: Thomason JJ, editor. Functional Morphology in Vertebrate Paleontology. New York: Cambridge University Press. pp. 205-218.
Kilbourne BM & PJ Makovicky. 2010. Limb bone allometry during postnatal ontogeny in non-avian dinosaurs. Journal of Anatomy 217: 135-152.
Kubo T & MJ Benton. 2007. Evolution of hindlimb posture in archosaurs: limb streeses in extinct vertebrates. Palaeontology 50 (6): 1519-1529.
Lee DV & SG Meek 2005. Directionally compliant legs influence the intrinsic pitch behaviour of a trotting quadroped. Proceedings of the Royal Society B 272(1563): 567–572.
Mallinson. 2010. CAD assessment of the posture and range of motion of Kentrosaurus aethiopicus Hennig 1915. Swiss J Geosci 103: 211-233.
McMahon, T (1975) Allometry and biomechanics: Limb bones in adult Ungulates. Am. Nat. 109:547-563.
Middleton KM & S Gatesy. 2000. Theropod forelimb design and evolution. Z J Linn Soc 128: 149-187
Organ CL. 2006. Biomechnics of ossified tendons in ornithopod dinosaurs. Paleobiology 31 (4): 652-665.
Papantoniou V, Avlakiotis P & R Alexander. 1999. Control of a robit dinosaur. Phil.Trans. R. Soc. Lond. B 354: 863-868.
Paul GS & P Christiansen. 2000. Forelimb posture in neoceratopsian dinosaurs: implications for gait and locomotion. Paleobiology, 26 (3): 450–465.
Romer AS. 1923. The ilium in dinosaurs and birds. Bulletin American Museum of Natural Histroy 48: 141-145.
Raichlen DA. 2006. Effects of limb mass distribution on mechanical power outputs during quadrupedalism. The Journal of Experimental Biology 209: 633-644
Romer AS. 1927. The pelvic musculature of ornithischian dinosaurs. Acta Zoologica 8: 225-275.
Sellers WI & PL Manning. 2007. Estimating dinosaur maximum running speeds using evolutionary robotics. Proceedings of Royal Society B 274: 2711-2716.
Senter P. 2007. Analysis of forelimb function in basal ceratopsians. Journal of Zoology 273: 305-314.
Sternberg CM. 1965. New restoration of hadrosaurian dinosaur. National Museum of Canada, Natural History Papers 1-5.
Taylor CR. 1978. Why change gaits? Recruitment of muscles and muscle fibers as a function of speed and gait. American Zoologist 18: 153.161.
Tereshchenko VS. 1994. A reconstruction of the erect posture of Protoceratops. Paleontological Journal 28 (1): 104-119.
Tereshchenko VS. 1996. A reconstruction of the locomotion of Protoceratops. Paleontological Journal 30 (2): 232-245.
Tereshchenko VS. 2008. Adaptive features of protoceratopoids (Ornithischia: Neoceratposia). Paleontological Journal 42 (3): 273-286.
Thompson S & R Holmes. Forelimb stance and step cycle in Chasmosaurus irvenenesis (Dinosauria: Neoceratopsia). Palaeontologica Electronica 10 (1): 5A.
Thulborn RA. 1982. Speeds and gaits of dinosaurs. Palaeogeography, Palaeoclimatology, Palaeoecology, 38: 227-256.
Thulborn RA. 1984. Preferred gaits of bipedal dinosaurs. Alcheringa 8 (3): 243-252.
Yates, Adam M., Matthew F. Bonnan, Johann Neveling, A. Chinsamy and Marc G. Blackbeard. 2009. A new transitional sauropodomorph dinosaur from the Early Jurassic of South Africa and the evolution of sauropod feeding and quadrupedalism. Proceedings of the Royal Society B, published online. doi:10.1098/rspb.2009.1440

 

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