Researchers say they’ve solved the mystery of the missing dinosaur eggs

AbstractA recent study by Norell et al. (2020) described new egg specimens for two dinosaur species, identified as the first soft-shelled dinosaur eggs. The authors used phylogenetic comparative methods to reconstruct eggshell type in a sample of reptiles, and identified the eggs of dinosaurs and archosaurs as ancestrally soft-shelled, with three independent acquisitions of a hard eggshell among dinosaurs. This result contradicts previous hypotheses of hard-shelled eggs as ancestral to archosaurs and dinosaurs. Here we estimate the ancestral condition for dinosaur and archosaur eggs by reanalyzing the original data from Norell et al. and that from a recent study on reptile eggshells (Legendre et al., 2020) with the addition of these new dinosaur specimens. We show that the recovery of dinosaur eggs as ancestrally soft-shelled is conditioned by the discretization of a continuous character (eggshell thickness), the exclusion of turtle outgroups from the original sample, and a lack of branch length information. When using a larger sample, calibrated trees, and a definition of hard-shelled eggs referencing their unique prismatic structure, we recover dinosaur and archosaur eggs as either hard-shelled or uncertain (i.e. equal probability for hard- and soft-shelled). This remaining ambiguity is due to uncertainty in the assessment of eggshell type in two dinosaur species, i.e. ∼1% of the total sample. We conclude that more reptile egg specimens and a strict comparative framework are necessary to decipher the evolution of dinosaur eggs in a phylogenetic context.

Download Full-text

K. Carpenter, K. F. Hirsch, & J. R. Horner, (eds) 1994. Dinosaur Eggs and Babies. xiv + 372 pp. Cambridge, New York, Port Chester, Melbourne, Sydney: Cambridge University Press. Price £55.00, US $79.95 (hard covers). ISBN 0 521 44342 3.

Geological Magazine ◽

10.1017/s0016756800011547 ◽

1995 ◽

Vol 132 (1) ◽

pp. 126-126

Author(s):

David Norman

Keyword(s):

New York ◽

Cambridge University ◽

Dinosaur Eggs

Download Full-text

Le synclinal danien-eocene de La Mourotte (Var)

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.s7-iv.1.87 ◽

1962 ◽

Vol S7-IV (1) ◽

pp. 87-91 ◽

Cited By ~ 3

Author(s):

Fernand Touraine

Keyword(s):

Upper Jurassic ◽

The South ◽

Northern Limit ◽

Southern Limit ◽

The North ◽

Bird Eggs ◽

Tectonic Study ◽

Dinosaur Eggs

Abstract Results of a stratigraphic and tectonic study of the Mourotte syncline, Provence, France, divide the structure into three parts. The northern part is composed of Hauterivian littoral beds containing Danian dinosaur eggs. The Danian limestone-sandstone series disappears at La Neuve while the marly upper Danian beds continue to the extreme northern limit of the syncline. In the central part the Hauterivian wedges out, and toward its southern limit the substratum is entirely upper Jurassic. In the southern part, the Danian limestones are only visible on the northeast border. Bird eggs collected in the area assign the southern part of the syncline to the Thanetian. Overturning is less noticeable in the north, becoming acute toward the south where the syncline is tightly overturned.

Download Full-text

Sur la datation des breches de la montagne Sainte-Victoire pres d'Aix-en-Provence

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.s7-vi.1.127 ◽

1964 ◽

Vol S7-VI (1) ◽

pp. 127-133

Author(s):

Fernand Touraine

Keyword(s):

Upper Cretaceous ◽

Lower Eocene ◽

Stratigraphic Position ◽

Dinosaur Eggs

Abstract Breccias in Sainte-Victoire mountain have been considered upper Cretaceous because of their stratigraphic position and the presence of dinosaur eggs. Other nearby breccias are considered Montian (lower Eocene). The supposed upper Cretaceous breccias are displaced from the principal masses by faulting but are the same Montian formation and age.

Download Full-text