While the dinosaur rule the Earth , our diminished ancestors evolved the crucial characteristics that made them successful after the end of the Cretaceous . ingest a great brain and a lowly bedding material of offspring are among these , and investigator now have more clue on when those adaptations began .
In an incredibly rare find , researchers have expose the fossilize remains of a mammal progenitor and her 38 baby . Never before have researcher found the fossilized remains of babies from a mammal precursor . As reported inNature , the creature , known asKayentatherium wellesi , is a beagle - size of it plant - eater that lived 185 million years ago . It has several traits in common with mammals , such as it likely get hair . However , it was n’t quite a mammal just yet .
The babies ’ skulls are diminished replicas of the adult one , which reveal they did not have peculiarly bountiful brains . Mammalian young be given to have bragging brains liken to their body size . The other bit of evidence is the number of offspring – 38 is unquestionably not a modest litter .
" These babies are from a really significant head in the evolutionary tree diagram , " lead author Eva Hoffman , a graduate student at the UT Jackson School of Geosciences , said in astatement . " They had a lot of features similar to modern mammalian , feature article that are relevant in understanding mammalian evolution . "
fossil found from just a few million years later show mammal ancestors already sporting big brains and small litter . rear many children and developing a heavy nous are activities that devour a tidy sum of energy . Researchers suggest that our ancestors stop up trade brood power for psyche power . These finding are important in our understanding of how we and other mammals evolve into what we are today .
" There are additional deep stories on the phylogenesis of developing , and the evolution of mammalian news and demeanor and physiology that can be squeezed out of a remarkable fogey like this now that we have the engineering to read it , " co - writer Professor Timothy Rowe explained .
The specimen was collected from a rock-and-roll geological formation 18 years ago in Arizona by Rowe , who had no idea it contained scores of offspring as well . It was another graduate scholarly person of his , Sebastian Egberts , who spotted a grain - sized speck of tooth enamel in 2009 . Detailed CT scan and subsequence analysis revealed the treasure obscure within .
