(A) Incompletely hatched egg from clutch P43. (B) Nearly intact circular outline of egg, possibly indicating that it did not hatch and no loose egg shells were found in the P6 clutch. (C) Compressed egg from the DR10 clutch showing the hatch window (arrow shows the gap) and some eggshells (circled) collected around the hatch window, possibly representing remains of the hatch window. (D) Egg of P26 coupling with curved outline. (E) Deformed egg from the P30 clutch showing the egg surfaces sliding over each other. Source: Dhiman et al., 2023, PLOS ONE, CCBY 4.0 (https://creativecommons.org/licenses/by/4.0/)
The discovery of more than 250 fossilized eggs reveals intimate details about the life of the titanosaurs according to a study in the Indian subcontinent released in the open access journal PLOS ONE by Harsha Dhiman, University of Delhi (India) and colleagues.
The Lameta Formation in the Narmada Valley of central India is known for dinosaur skeletons and eggs from the late Cretaceous period (roughly 100.5 million to 66 million years ago). Recent work in the area has uncovered 92 nest sites containing a total of 256 fossil eggs of titanosaurs, some of the largest dinosaurs that ever lived. A detailed study of these nests allowed Dhiman and his colleagues to draw conclusions about the living habits of these dinosaurs.
The authors identified six different types of eggs (oospecies), suggesting a greater diversity of titanosaurs than is represented by skeletal remains from this region. From the arrangement of the nests, the team concluded that these dinosaurs buried their eggs in shallow pits, like modern crocodiles. Certain pathologies found in the eggs, such as a rare case of “egg within an egg,” indicate that sauropod titanosaurs had similar reproductive physiology to birds and may have laid their eggs sequentially, as is the case in modern birds .
New insights
The presence of many nests in the same area suggests that these dinosaurs, like many modern birds, displayed colonial nesting behavior. But the close spacing of the nests left little room for adult dinosaurs, supporting the idea that adults leave their (newborn) young to fend for themselves.
Details of dinosaur reproductive habits can be difficult to determine. These fossil nests provide a wealth of data on some of the largest dinosaurs in history, dating from just before the end of the Dinosaur Age. The insights gained from this study go a long way in helping paleontologists understand how dinosaurs lived and evolved.
Harsha Dhiman, lead author of the study, added: “Our research revealed the presence of an extensive breeding ground of sauropod titanosaur dinosaurs in the study area and provides new insights into the nest maintenance conditions and reproductive strategies of sauropod titanosaur dinosaurs close to their extinction”.
Guntupalli VR Prasad, also from the University of Delhi, coauthor and leader of the research team, said: “Together with the Jabalpur dinosaur nests in the upper Narmada valley in the east and those in Balasinor in the west, the new nest sites are the Dhar District site in Madhya Pradesh (central India) with an eastwest extension of about 1,000 kilometers forms one of the largest dinosaur breeding grounds in the world.