Sordes pilosus is a genus of pterosaurs (or "Flyers" in Land Before Time terms) that lived during the Late Jurassic, in what is now Kazakhstan. Its name means "hairy filth" or "dirty hair"; there is an error in its scientific name: Sordes is a feminine word, and thus the second part should be pilosa, but this has yet to be amended.
It was believed to be a fish-eating creature and had a wingspan of two feet. Sordes is important to paleontology and pterosaurs in particular because it was the first-known pterosaur fossil to show that pterosaurs had a coat similar to fur.
Sordes in The Land Before Time
A pterosaur which may be Sordes appears in the first film, as one of many creatures that witness Littlefoot's birth. They appear correctly as small fuzzy creatures (unlike many other pterosaurs in The Land Before Time, they are correctly shown to have an extensive furlike coat). They appear alongside Pterodactylus, Edaphosaurus, Hylonomus, Diphydontosaurus, Lesothosaurus', Eryops, and a few other reptiles. They make a cameo appearance in The Land Before Time III: The Time of the Great Giving trying to escape the fire consuming the Great Valley, one also appears in the beginning of The Land Before Time IV: Journey Through the Mists in The Land of Mists.