World's oldest eggs reveal dinosaur evolution

[Still Waters]

A study of the world's earliest known dinosaur eggs reveals new information about the evolution of dinosaur reproduction.

An international team of researchers led by Robert Reisz of the Department of Biology at the University of Toronto Mississauga studied the fossilized remains of eggs and eggshells discovered at sites in Argentina, China and South Africa—widely separated regions of the supercontinent Pangea. At 195 million years old, they are the earliest known eggs in the fossil record, and they were all laid by a group of stem sauropods—long-necked herbivores that ranged in size from four to eight metres in length and were the most common and widely spread dinosaurs of their time.

https://phys.org/news/2019-03-world-oldest-eggs-reveal-dinosaur.html

[Piney]

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Reisz adds that the study raises interesting questions for future investigation. "For example, we would like to understand why dinosaurs and their avian descendants never developed viviparity (live birth) and continued to rely on egg laying, while non dinosaurian reptiles and mammals, including ancient aquatic reptiles succeeded in evolving this more advanced reproductive strategy."Read more at: https://phys.org/news/2019-03-world-oldest-eggs-reveal-dinosaur.html#jCp

Weight reduction in flight and while running. Which uses less caloric energy. You don't expend as much energy while swimming.