Filling in the Blanks

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.

Disparity Notebook

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.

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

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.

Outlining the Paper

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!)

Forelimb Proportions, Ternary Style

An important part of our manuscript will simply be a description of limb proportions in ornithischian dinosaurs. For this, ternary plots really have no parallel. These graphs simultaneously plot three variables in two dimensions on an equilateral triangle. And wouldn’t you know it – we can consider each dinosaur limb to have three major bones! In the case of the forelimb, these are the humerus, radius, and metacarpal III (see this post for an explanation of why we would look at the radius rather than the ulna).

In the figure below, I’ve generated a quick and dirty ternary plot for ornithischian dinosaur forelimb proportions. You’ll note that ornithischians occupy a very small chunk of morphospace! Hadrosaurs (and one or two non-hadrosaurid ornithopods; likely ones very close phylogenetically, such as Tethyshadros) have their own special brand of metacarpal lengths (this has been discussed before). It’s an absolute shame that stegosaurs and pachycephalosaurs simply aren’t represented!

Comments or thoughts are very welcome – and if you want to generate other versions of the plot, all data are freely available (see below). In fact, we encourage you to play with the data. Drop a note in the comments if there’s an image you’d like to post here, too!

Ornithischian Limb Proportions (A=ankylosaurs; C=ceratopsians; H=hadrosaurs; O=non-hadrosaur ornithopods)

What Species Are Included?

• Any species for which the three major bones of the forelimb (humerus, radius, and MC III) were known. For taxa with multiple individuals, only the largest was used. Known juveniles are excluded, to my knowledge.
  

How Was It Plotted?

• The following text provides the sequence of commands that I typed into the terminal, to produce the plot. I created this plot using R 2.10.1, running on Ubuntu 10.04. The file “forelimb_tern.csv” can be downloaded here. It is taken from the “Fore Hind 1” tab in the spreadsheet posted the other day.
• These commands read the data file, plot a ternary plot, and export said plot to a PDF. [Important: Your web browser may “cleverly” reformat the quote marks into ‘smart quotes’; so, reformat back before pasting into your terminal]
• After I had the PDF, I manipulated it in GIMP and Inkscape, in order to produce the graphic seen above.
• This is surely the most inelegant way to accomplish the task; I received some odd errors when trying to add a legend, and never figured out how to plot just the portion of the graph with the data. If anyone figures this out, I’d love to hear it! We will almost certainly produce a nicer version of this plot for the final manuscript.

R
library(vcd)
ornith=read.csv(“forelimb_tern.csv”)
attach(ornith)
colors <- c(“black”,”red”,”green”,”blue”)
pch <- substr(levels(taxon), 1, 1)
pdf(“test.pdf”)
ternaryplot(
ornith[,2:4],
pch = as.character(taxon),
col = colors[as.numeric(taxon)],
main = “Ornithischian Limb Bone Proportions”
)
dev.off()

Relevant References for the ODP

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

 

• Alexander R. 1985. Meachanics 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.

• Bonnan MF & P Senter. 2007. Were the basal sauropodomorph dinosaurs Plateosaurus and Massospondylus habitual quadropeds. Special Papers in Palaeontology 77: 139–155

• Carrano MT. 2000. Homoplasy and the evolution of dinosaur locomotion. Paleobiology 26 (3): 489-512.

• Dilkes DW. 2000. Apendicular 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. Psoture 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.

• Kilbourne BM & PJ Maklovicky. 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.

• 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.

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The Data Set (as it sits now)

The ODP has accumulated a whole lot of data, and now we have to make some sense out of it. The first step was to pare it down from the original monstrous mass. Based on a very lively discussion (see this post and links therein), the data are pretty much trimmed. In addition to posting a link to those data (in response to this query by Hiro), I wanted to explain some of what I’ve done with the data.

The file, freely available as an Excel workbook, contains several spreadsheets. These are explained below, by spreadsheet:

• To Analyze: Includes all of the data, minus highly incomplete or juvenile specimens. As you may recall, juveniles were rates as those listed as such in the literature, or individuals which were less than 2/3 the size of the largest individual for a species.
• Deletion Candidates: The home for the highly incomplete or juvenile specimens mentioned above. We don’t want to throw them away, after all.
• Fore Hind1 & ForeHind 2: Worksheets where I was just playing around with various ways of looking at the combined data.
• Ratios: A whole bunch of ratios between various limb elements; it’s worth exploring. This will require a more detailed post in the not-so-distant future, to explain many of these.

You’ll probably notice the abbreviation “IM”. This refers to an intermembral index – basically, the ratio between forelimb and hind limb length. There are several ways to calculate it. These include:

• IM1(U)=(Humerus+Ulna)/(Femur+Tibia)
• IM2(U)=(Humerus+Ulna+MCIII)/(Femur+Tibia+MTIII)
• IM1(R)=(Humerus+Radius)/(Femur+Tibia)
• IM2(R)=(Humerus+Radius+MCIII)/(Femur+Tibia+MTIII)

There are several other possible ways to calculate this, but they often aren’t practical in terms of missing data (many more tibiae are known than fibulae). I would suggest that intermembral indices calculated with the radius are most desirable, for two reasons. First, the radius is a widely preserved and measured bone. Second, you don’t have to deal with the olecranon process, which exaggerates the functional length of the ulna in some animals.

There you have it! Comments?

Return of the ODP!

Mantellisaurus, a big ornithopod

It’s bAAAAaaaack!

The hiatus has been a long one (far longer than expected), but now it’s time to get the show on the road again. Life has been busy for everyone, but it’s time to make some time for the ODP. Basically, Wedel was over the other night and reminded me I should do a blog post. There’s so much to see, so much to do, so much to talk about! Here’s some highlights:

• The dataset is pretty much all together; we just have to finish analyzing the darned thing. Stay tuned for more.
• I (Andy) had a fun time at SVP in Pittsburgh, and got to meet a number of ODP volunteers there. Awesomeness!
• Casey Holliday and colleagues published an interesting article on articular cartilage in dinosaur limb bones, suggesting that limb lengths may have been up to 10 percent longer than we see just from the bones. Read the paper for free at PLoS ONE – anyone interested in doing a guest post on it, perhaps?
• We should probably start putting together a reference list of papers related to the mission of the ODP: analyzing limb proportions in ornithischian dinosaurs. I’ll probably start a thread for that, too.

As added incentive, I made the ODP one of my personal goals for the Paleo Project Challenge. If you haven’t checked out the challenge yet, please do so. The main premise: make a plan to complete a project, or else face public humiliation. Let’s see if it works. . .

That’s all for now!

Image credit: By Steveoc 86, from Wikimedia Commons.

ODP on hiatus

Hi all,

You may be justifiably wondering where the heck your feckless leaders are. The sad answer is that we’re temporarily swamped. Andy and I have been caught  up in the end-0f-school-year activities at our respective institutions, and Andy leaves today for a round-the-world research trip that will take him to China, Madagascar, Kenya, and England. Mike is consumed with day-job responsibilities, and I am gearing up for summer teaching.

This is part of the ebb and flow of academic and professional life, and we knew it was coming, which is why we originally planned to try to get a manuscript off before the storm hit. Obviously that didn’t happen, and it’s not going to happen in the next couple of months, so we (Andy, Mike, and me) are going on hiatus for a bit. We’ll get moving again toward the end of summer.

So, thanks again, from all of us, to everyone who has contributed. It’s been a great thrill for us to see that the ODP is actually working, and we’re sorry to have to bow out for a bit. But fear not, we will be back, and the project will go on to completion. In the meantime, the data are available for further tinkering, and we’ll leave the comment fields open in case you have any brainstorms.

Have a great summer, and we’ll see you on the other side.

New ODP article in the Palaeontological Association newsletter

The new issue of the Palaeontological Association newsletter dropped through the letterbox this morning, and I was delighted to see that our article on the Open Dinosaur Project was included.  The PalAss newsletter, despite its name, is not a couple of mimeographed-and-stapled sheets, but a reasonably substantial publication (98 glossy pages in the current issue), so hopefully it will help to raise our profile, especially among more traditional professionals who get their news from dead-tree media rather than the Internet.

You can download the whole newsletter as a single PDF from the PalAss site, or just the OPD article (five pages) if you prefer.

Reference

Taylor, Michael P., Andrew A. Farke and Mathew J. Wedel. 2010. The Open Dinosaur Project. The Palaeontological Association Newsletter 73:59-63.