Catopsbaatar
Catopsbaatar is a genus of multituberculate, an extinct order of rodent-like mammals. It lived in what is now Mongolia during the late Campanian age of the Late Cretaceous Period, about 72 million years ago. The first fossils were collected in the early 1970s, and the animal was named as a new species of the genus "Djadochtatherium " in 1974, "D. catopsaloides". The specific name refers to the animal's similarity to the genus "Catopsalis". The species was moved to the genus "Catopsalis" in 1979, and received its own genus ("Catopsbaatar", Greek and Mongolian for "visible hero") in 1994. Five skulls, one molar, and one skeleton with a skull are known; the latter is the genus' most complete specimen. "Catopsbaatar" was a member of the family Djadochtatheriidae.
Calcar
The oldest known ancestor to present day bats, "Icaronycteris index", apparently did not have a calcar or spur as evidenced by fossil remains. 
The oldest known bat with a calcar is "Onychonycteris", which lived in the early Eocene.
"Onychonycteris" had a long calcar, indicative of a broad tail membrane.
In describing "Onychonycteris" in 2008, Simmons hypothesized that its calcar was more relevant to the mechanism of flight than capturing prey.