No teeth? No problem: Dinosaur species had teeth as babies, lost them as they grew

Limusaurus inextricabilisCurrent Biology

Limusaurus"This discovery is important for two reasons," said James Clark, a co-author on the paper and the Ronald Weintraub Professor of Biology at the George Washington University's Columbian College of Arts and Sciences. "First, it's very rare to find a growth series from baby to adult dinosaurs. Second, this unusually dramatic change in anatomy suggests there was a big shift in' diet from adolescence to adulthood."

 is part of the theropod group of dinosaurs, the evolutionary ancestors of birds. Dr. Clark's team's earlier research of  described the species' hand development and notes that the dinosaur's reduced first finger may have been transitional and that later theropods lost the first and fifth fingers. Similarly, bird hands consist of the equivalent of a human's second, third and fourth fingers.

Limusaurus"For most dinosaur species we have few specimens and a very incomplete understanding of their developmental biology," said Josef Stiegler, a graduate student at George Washington University and co-author. "The large sample size of allowed us to use several lines of evidence including the morphology, microstructure and stable isotopic composition of the fossil bones to understand developmental and dietary changes in this animal."