“Adalatherium” was much larger than most:
Its “bizarre” features include more trunk vertebrae than most other mammals, muscular hind limbs that were placed in a more sprawling position (similar to modern crocodiles) coupled with brawny sprinting front legs that were tucked underneath the body (as seen in most mammals today), front teeth like a rabbit and back teeth completely unlike those of any other known mammal, living or extinct, and a strange gap in the bones at the top of the snout …
Not only did Adalatherium have rabbit- or rodent-like ever-growing front teeth, but the back teeth are completely unlike those of any other known mammal, living or extinct. If just these teeth had been found, the mystery of what this animal was would likely not have been solved! Added to the seeming chaos is a hole in the top of the snout for which there is simply no parallel.
About the size of a Virginia opossum, the 3.1 kg Adalatherium was very large for its day. While not particularly large by today’s standards, it was a giant compared to the mostly shrew- and mouse-sized mammals living in the Cretaceous.
Taylor & Francis Group, “The ‘crazy beast’ that lived among the dinosaurs” at ScienceDaily
The paper is open access.
We bet if the researchers keep digging, they will come up with many stranger mammals. Also, if enough were known, it will probably turn out that the animals were well adapted to their environment. Things can easily seem bizarre if we actually do not know the reason for them.
“From outer space” is how the researcher describes Adalatherium in this vid: