Identifying a Metatherial Skull (3)-Diprotodonts

If a skull belongs to O. Diprotodontia one way to immediately separate out two families from the rest is to look at the size of the skull: F. Petauridae and F. Acrobatidae are both types of flying-squirrel-like creatures that have the smallest skulls out of all the diprotodont orders we looked at in lab. The difference between them is that F. Petauridae has a squamosal bone (back part of the zygomatic arch) that has honeycomb-like holes in it, whereas F. Acrobatidae does not. To identify the rest of the order, looking at the angular process can help narrow down what family a skull belongs to: although most marsupials have a reflected angular process, there is one family that does not. This family is F. Phascolarctidae (koalas) which also has a long paroccipital process and selenodont teeth to accommodate its herbivorous diet. If the angular process is reflected, a possible next step is to look at the gap between the incisors and the molar row. This is called the diastema, and if it is large then it could belong to one of two families; either F. Macropodidae (kangaroos and their ilk) or F. Vombatidae (wombats). What distinguishes the two, aside from skull shape, is the fact that F. Vombatidae has 1/1 incisors—meaning that it only has one incisor on each side of its head both on the lower and upper jaw—while F. Macropodidae has 3 upper incisors that are blade-like and angled for cutting. This leaves three families, F. Pseudoceiridae, F. Phalangeridae, and F. Potoroidae, which all have similar skull shapes and sizes. F. Pseudocheiridae is the smallest, while F. Phalangeridae is the largest. F. Potoroidae and F. Phalangeridae both have enlarged premolars, however they differ in each family as they are angled outwards in F. Phalangeridae and in line with the molar row in F. Potoroidae. This leaves  F. Pseudoceiridae, which has no enlarged premolars and instead can be distinguished by its selenodont teeth.