Project 1139: H. N. Woodward, E. A. Freedman Fowler, J. O. Farlow, J. R. Horner. 2015. Maiasaura, a model organism for extinct vertebrate population biology: a large sample statistical assessment of growth dynamics and survivorship. Paleobiology. 41 (4):503-527.
Specimen: † Maiasaura peeblesorum (MOR:005 T16)
View: Tibia transverse sections

Abstract

Fossil bone microanalyses reveal the ontogenetic histories of extinct tetrapods, but incomplete fossil records often result in small sample sets lacking statistical strength. In contrast, a histological sample of 50 tibiae of the hadrosaurid dinosaur Maiasaura peeblesorum allows predictions of annual growth and ecological interpretations based on more histologic data than any previous large sample study. Tibia length correlates well (R2>0.9) with diaphyseal circumference, cortical area, and bone wall thickness, thereby allowing longitudinal predictions of annual body size increases based on growth mark circumference measurements. With an avian level apposition rate of 86.4 μm/day, Maiasaura achieved over half of asymptotic tibia diaphyseal circumference within its first year. Mortality rate for the first year was 89.9% but a seven year period of peak performance followed, when survivorship (mean mortality rate=12.7%) was highest. During the third year of life, Maiasaura attained 36% (x=1260 kg) of asymptotic body mass, growth rate was decelerating (18.2 μm/day), cortical vascular orientation changed, and mortality rate briefly increased. These transitions may indicate onset of sexual maturity and corresponding reallocation of resources to reproduction. Skeletal maturity and senescence occurred after 8 years, at which point the mean mortality rate increased to 44.4%. Compared with Alligator, an extant relative, Maiasaura exhibits rapid cortical increase early in ontogeny, while Alligator cortical growth is much lower and protracted throughout ontogeny. Our life history synthesis of Maiasaura utilizes the largest histological sample size for any extinct tetrapod species thus far, demonstrating how large sample microanalyses strengthen paleobiological interpretations.


Read the article »

Article DOI: 10.1017/pab.2015.19

Project DOI: 10.7934/P1139, http://dx.doi.org/10.7934/P1139
This project contains
  • 8 Media
  • 1 Document
  • 2 Folios
  • 1 Taxon
  • 3 Specimens
Total size of project's media files: 235.99M

Download Project SDD File
Currently Viewing:
MorphoBank Project 1139

    This research
    supported by

    Authors' Institutions

    • Indiana University-Purdue University At Indianapolis

    • Montana State University

    • Museum of the Rockies



    Members

    member name taxa specimens media media
    notes
    Holly Woodward
    Project Administrator
    Last logged in 10/01/15
    1388


    Project has no matrices defined.



    Project views

    type number of views Individual items viewed (where applicable)
    Total project views16599
    Project overview2650
    Media views6189Media search (2872 views); M326122 (374 views); M340007 (444 views); M326119 (412 views); M326126 (418 views); M326125 (399 views); M340003 (414 views); M326124 (423 views); M326121 (433 views);
    Documents list1149
    Folio views1208Folio list (633 views); MOR 005 T16 (259 views); MOR 005 T46 (316 views);
    Specimen list2482
    Taxon list1332
    Bibliography677
    Views for media list912




    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project206
    Project downloads197
    Media downloads9M326124 (2 downloads); M326121 (2 downloads); M326119 (1 download); M340007 (2 downloads); M340003 (2 downloads);