Project 1218: T. M. Cullen, D. C. Evans, M. J. Ryan, P. J. Currie, Y. Kobayashi. 2014. Osteohistological variation in growth marks and osteocyte lacunar density in a theropod dinosaur (Coelurosauria: Ornithomimidae). BMC Evolutionary Biology.
Specimen: † Ornithomimus edmontonicus (ROM:852)

Abstract

Background
Osteohistological examinations of fossil vertebrates have utilized a number of proxies, such as counts and spacing of lines of arrested growth (LAGs) and osteocyte lacunar densities (OLD), in order to make inferences related to skeletochronology and mass-specific growth rates. However, many of these studies rely on samplings of isolated bones from single individuals. These analyses do not take individual variation into account, and as a result may lead to misleading inferences of the physiology of extinct organisms. This study uses a multi-element, multi-individual sampling of ornithomimid dinosaurs to test the amount of individual variation in the aforementioned osteohistological indicators. Based on these results we also assess the conclusions of previous studies that tested paleohistological hypotheses using isolated elements

Results
LAG number was found to be consistent within the hind limb bones of each individual, with the exception of the fibula, which preserves one additional LAG. Considerable differences in LAG spacing were found between elements of the sampled individuals, with larger variation found in elements of the foot compared with the femur, fibula, and tibia. Osteocyte lacunar density ranged between 29000 and 42000 osteocyte lacunae per mm3, and was found to vary more between hind limb bones of an individual and within bones, than between the average values of individuals.

Conclusions
The variation in LAG number and LAG spacing between hind limb elements suggests that direct comparisons of these elements may be misleading, and that LAG spacing is not a reliable proxy for mass-specific growth rates of an individual. Sampling of multiple bones should be performed as an internal check of model-based LAG retrocalculation and growth equations. The observation that osteocyte lacunar density varies more between individual bone elements than between average individual values suggests that, the choice of sampled element can greatly influence the result, and care should be taken to not bias interpretations of the physiology of fossil tetrapods.



Read the article »

Article DOI: 10.1186/s12862-014-0231-y

Project DOI: 10.7934/P1218, http://dx.doi.org/10.7934/P1218
This project contains
  • 40 Media
  • 2 Taxa
  • 4 Specimens
Total size of project's media files: 225 MB

Download Project SDD File
Currently Viewing:
MorphoBank Project 1218


    Members

    member name taxa specimens media media
    notes
    Thomas Cullen
    Project Administrator
    Last logged in 12/01/14
    244040


    Project has no matrices defined.



    Project views

    type number of views Individual items viewed (where applicable)
    Total project views26685
    Project overview3049
    Media views20125Media search (4031 views); M333237 (391 views); M339654 (444 views); M339651 (383 views); M339646 (410 views); M333245 (403 views); M339649 (366 views); M333258 (369 views); M333255 (389 views); M333252 (393 views); M339656 (403 views); M333239 (388 views); M339652 (398 views); M339645 (414 views); M333259 (376 views); M333261 (406 views); M333263 (431 views); M333257 (391 views); M333262 (379 views); M333246 (372 views); M333240 (413 views); M333254 (351 views); M333244 (415 views); M333253 (420 views); M333256 (392 views); M333250 (431 views); M333247 (411 views); M333236 (423 views); M339653 (393 views); M339655 (409 views); M333243 (463 views); M339650 (404 views); M333249 (398 views); M339648 (404 views); M333251 (401 views); M333238 (382 views); M339647 (408 views); M333241 (416 views); M333248 (434 views); M333242 (434 views); M333260 (386 views);
    Specimen list2442
    Taxon list1069




    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project172
    Media downloads29M333239 (3 downloads); M333260 (4 downloads); M333245 (4 downloads); M333236 (4 downloads); M333243 (2 downloads); M333238 (2 downloads); M339645 (1 download); M333261 (2 downloads); M333244 (3 downloads); M333241 (2 downloads); M333240 (1 download); M333242 (1 download);
    Project downloads143