Pelvis morphology suggests that early Mesozoic birds were too heavy to contact incubate their egg

Deeming, Charles and Mayr, Gerald (2018) Pelvis morphology suggests that early Mesozoic birds were too heavy to contact incubate their egg. Journal of Evolutionary Biology . ISSN 1010-061X

#223 Deeming & Mayr JEvolBiol.pdf

Request a copy
JEB manuscript text accepted ALL preprint.pdf
31436 31291 Deeming_et_al-2018-Journal_of_Evolutionary_Biology.pdf
[img] PDF
#223 Deeming & Mayr JEvolBiol.pdf - Whole Document
Restricted to Repository staff only

JEB manuscript text accepted ALL preprint.pdf - Whole Document

31436 31291 Deeming_et_al-2018-Journal_of_Evolutionary_Biology.pdf - Whole Document

Item Type:Article
Item Status:Live Archive


Numerous new fossils have driven an interest in reproduction of early birds, but direct evidence remains elusive. No Mesozoic avian eggs can be unambiguously assigned to a species, which hampers our understanding of the evolution of contact incubation, which is a defining feature of extant birds. Compared to living species, eggs of Mesozoic birds are relatively small, but whether the eggs of Mesozoic birds could actually have borne the weight of a breeding adult has not yet been investigated. We estimated maximal egg breadth for a range of Mesozoic avian taxa from the width of the pelvic canal defined by the pubic symphysis. Known elongation ratios of Mesozoic bird eggs allowed us to predict egg mass and hence the load mass an egg could endure before cracking. These values were compared to the predicted
body masses of the adult birds based on skeletal remains. Based on 21 fossil species, we show that for nonornithothoracine birds body mass was 187% of the load mass of the eggs. For Enantiornithes, body mass was 127%
greater than the egg load mass, but some early Cretaceous ornithuromorphs were 179% heavier than their eggs could support. Our indirect approach provides the best evidence yet that early birds could not have sat on their eggs without running the risk of causing damage. We suggest that contact incubation evolved comparatively late in birds.

Keywords:Contact incubation, Egg size, Mesozoic bird, Pelvic canal width
Subjects:F Physical Sciences > F641 Palaeontology
C Biological Sciences > C140 Developmental/Reproductive Biology
Divisions:College of Science > School of Life Sciences
Related URLs:
ID Code:31436
Deposited On:27 Mar 2018 08:30

Repository Staff Only: item control page