Multiple Dinosaur Egg-Shell Occurrence in an Upper Cretaceous Nesting Site from Patagonia

Rodolfo A. Coria; Leonardo Salgado; Luis M. Chiappe

doi:10.5710/amgh.v47i1.4

Exceptional preservation of a Late Cretaceous dinosaur nesting site from Mongolia reveals colonial nesting behavior in a non-avian theropod

Geology ◽

10.1130/g46328.1 ◽

2019 ◽

Vol 47 (9) ◽

pp. 843-847 ◽

Cited By ~ 2

Author(s):

Kohei Tanaka ◽

Yoshitsugu Kobayashi ◽

Darla K. Zelenitsky ◽

François Therrien ◽

Yuong-Nam Lee ◽

...

Keyword(s):

Upper Cretaceous ◽

Bird Species ◽

Nesting Behavior ◽

Gobi Desert ◽

Exceptional Preservation ◽

Colonial Nesting ◽

Nesting Site ◽

High Concentrations ◽

Lithologic Unit ◽

Nesting Season

Abstract Colonial nesting behavior has been inferred in a variety of non-avian dinosaurs based on high concentrations of nests preserved in an area, but sedimentologic and taphonomic evidence demonstrating the contemporaneity of the nests is often lacking. A new nesting site discovered in the Upper Cretaceous Javkhlant Formation of the eastern Gobi Desert, Mongolia, preserves at least 15 egg clutches laid by a probable non-avian theropod, and provides strong evidence for colonial nesting in a non-avian dinosaur. The occurrence of the clutches at the top of a common paleosurface, the distribution of eggshell fragments within clutches, the presence of a consistent two-layer sediment infill within eggs, and a thin marker lithologic unit blanketing all the clutches indicate the clutches were laid and hatched in a single nesting season. Despite the absence of sedimentologic evidence indicative of nest structure, statistical analyses of egg characteristics and facies association reveal the clutches were likely incubated in covered or buried nests. Based on the number of hatched clutches, the hatching success rate of the colony was high (60%), similar to that of extant crocodylian populations and bird species that attend and/or protect their nests during the incubation period, which indicates nest attendance behavior in the Javkhlant theropods. Thus, colonial nesting with parental attendance, widespread in extant birds, likely evolved initially among non-brooding, non-avian dinosaurs to increase nesting success.

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A new Upper Cretaceous titanosaur nesting site from La Rioja (NW Argentina), with implications for titanosaur nesting strategies

Palaeontology ◽

10.1111/pala.12234 ◽

2016 ◽

Vol 59 (3) ◽

pp. 433-446 ◽

Cited By ~ 8

Author(s):

E. Martín Hechenleitner ◽

Lucas E. Fiorelli ◽

Gerald Grellet-Tinner ◽

Léa Leuzinger ◽

Giorgio Basilici ◽

...

Keyword(s):

Upper Cretaceous ◽

Nesting Site ◽

La Rioja

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Eggs of titanosaurid sauropods from the Upper Cretaceous of Auca Mahuevo (Argentina)

Canadian Journal of Earth Sciences ◽

10.1139/e04-049 ◽

2004 ◽

Vol 41 (8) ◽

pp. 949-960 ◽

Cited By ~ 42

Author(s):

Gerald Grellet-Tinner ◽

Luis M Chiappe ◽

R Coria

Keyword(s):

Late Cretaceous ◽

Upper Cretaceous ◽

Horizontal Layer ◽

South American ◽

Eggshell Thickness ◽

The South ◽

Pore Canal ◽

Nesting Site ◽

Innermost Layer ◽

Canal Network

We provide a detailed description of the sauropod eggs from the Late Cretaceous nesting site of Auca Mahuevo (Neuquén Province, Argentina), the only eggs that are unequivocally associated with titanosaurid dinosaurs. These eggs are subspherical averaging 132 by 115 mm. Well-preserved specimens display a pronounced eggshell ornamentation that consists mostly of single nodes averaging 0.58 mm in diameter and 0.28 mm in height (base to apex) with internodular values of 0.52 to 0.87 mm. The pore canal network consists of vertical and horizontal canals intersecting at the bases of eggshell units. Vertical canals may fork defining a "Y" pattern and their diameters vary between 0.08 and 0.2 mm. Their surficial apertures of 0.15 to 0.29 mm are funnel like and located between the surficial nodes. In pristine specimens, the eggshell thickness equals 1.31 mm, and radial sections exhibit a single structural horizontal layer composed of juxtaposed shell units consisting of acicular calcite crystals radiating from an organic core. Relying only on taxonomically identified oological material, we regard this character also shared in the innermost layer (layer 1) of Deinonychus antirrhopus, oviraptorid theropods, and observed during an early oogenetic stage in extant bird as primitive for saurischians. The eggshell morphology advocates that these eggs were likely incubated in moist nesting environments, perhaps such as nests covered with vegetal matter. Examination of the South American megaloolithid eggshells reveals that the titanosaurid eggs from Auca Mahuevo are mostly similar to those described as Megaloolithus patagonicus and Megaloolithus pseudomamillare.

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