Not hard, not soft, the earliest dino eggs may have been of a 'leathery' texture to protect against damage: study

Often confused for mere pebbles by the untrained eye, fossilized dinosaur eggs unlock a treasure trove of knowledge about the bygone era of reptilian reproduction and evolution. Despite having only their stony remnants as our guide, the world of dino eggs remains a realm of mystery. Whether these ancient treasures were adorned in silk or concealed profound secrets, the truth lies entombed with their calcified remains.

In a recent revelation shaking the foundations of paleontology, researchers discovered that the initial dinosaur eggs were not the rigid structures previously believed. This revelation caused ripples in the scientific community, challenging the traditional image of hard-shelled eggs. However, a recent study has thrown another curveball, unraveling the story of a fossilised cluster comprising three adult dinosaur skeletons and five litters of dinosaur egg fossils dating back 190 million years to the Early Jurassic period.

Discovered in the rugged terrain of Southwest China's Guizhou Province, these eggs, each cradling precious embryos, belonged to the Qianlong shouhu — a previously undiscovered sauropodomorph species. This medium-sized herbivorous dinosaur, weighing almost 1,000 kilograms and stretching six meters in length, defied conventional egg categorizations with its unique attribute, christened by paleontologists as "leathery eggs."

Delving into the microstructure of these fossil eggs, the Chinese research team revealed that the earliest dinosaur eggs boasted a leathery texture, providing enhanced protection against potential damage. Moreover, the embryos within exhibited disparities from the adults, featuring fewer teeth, proportionally longer skulls, and a more vertically oriented anterior snout.

Adding to the intrigue, limb ratios hinted that adult Qianlong shouhu could navigate on hindlimbs, while the juveniles likely traversed on all fours. However, the plot thickens with evidence suggesting that these dinosaurs might have practiced colonial nesting — a behaviour observed in birds and reptiles, where individuals share a nesting site surrounded by similar species. Researchers propose that the Qianlong shouhu, in all likelihood, extended parental care to its offspring.

Bestowed with the name "Shou Hu Qian Long," where "Qian" signifies their origin in Guizhou Province and "Shou Hu" translates to "safeguard" in Chinese, these fossils underscore the nurturing instincts of this colossal creature. Notably, these fossils, unearthed in 1999, mark the earliest instance where a dinosaur fossil preserved an attached egg with its embryo, a milestone on the prehistoric timeline.

For those eager to delve deeper into this captivating discovery, the comprehensive findings of this study are detailed in the National Science Review.