After a series of two excavation trips, the researchers recovered 1,550 separate bone and bone fragments and, in total, remains of at least 15 distinct individuals with ranges from young infants to old adults. The sheer massive number of fossils found, the researchers said, allowed them to be more certain that this is indeed a new species, and not simply a collection of bones from two different, known species. They analyzed every anatomical feature —skull, hands, feet, teeth, etc. — separately, using specialized teams working independently. Each team came to the same conclusion: the features came from the same species, and thus collectively, the fossils as a whole must belong to the same species.