deltae specimens — some bone fragments and some nearly complete skeletons — when they noticed that the limb bones of the animal came in different sizes.
The size differences weren't based on when or where the fossils were found, so Otoo realized that they were looking at bones from animals of different ages.By looking at growth rings in the bones, the team found that W.
All of the nine specimens they studied were older juveniles and young adults, Otoo said, so it seems that the animals bulked up to around 3.3 feet (1 meter) in length as they neared sexual maturity and then grew larger more slowly in later adulthood. ."You have this animal that is racing to get to reproductive age to get to at least a decent size really quickly, because the best way to get yourself out of a predator's range of prey items is to get bigger," Otoo told Live Science. .It was surprising to see this pattern in such an early tetrapod, Otoo added, because scientists expected rapid early growth to be linked to a terrestrial lifestyle and restricted to mammals, birds and reptiles with higher metabolisms than those of early tetrapods. ."To find [rapid growth] in as old an animal as Whatcheeria and as primitive as Whatcheeria was really unexpected," Otoo said.Other types of tetrapods from this era grew more slowly and steadily, Otoo said, so it's clear that these early four-legged animals were trying a number of different evolutionary pathways to success. .