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Description
Oviraptorosaurs went through a massive diversification event in the Eocene; indeed, the ancestors of most modern representatives of this lineage had appeared by the Late Eocene. However, it was during the Oligocene that these animals really cemented themselves as major components of Eurasian faunal communities. In North America, the Occisoraptorids (descendants of Asian Oviraptorids) first appeared during the Early Eocene as small generalised omnivores but, by the end of the period, had begun to develop heavier skulls and beaks adapted for shearing flesh. The Occisoraptorids survived the Grand Coupre extinction event with minimal losses and continued into the Oligocene with little change. During the Middle Oligocene, the bulky, scavenging Simotyrannosaurids died out, leaving the mid-size predator/scavenger niche with a void to be filled. The already carnivorous Occisoraptorids quickly moved into this niche and became major predators up to 8m in length.

Although they lived alongside Boreoraptorine Dromaeosaurs, the Occisoraptorids avoided competition with them by inhabiting a different ecological niche. Whereas the Boreoraptorines were ambush predators with an exclusively carnivorous diet, their Oviraptorosaur contemporaries were more flexible; they regularly scavenged from carcasses, incorporated the occasional tuber or root into their diet when times got tough as well as taking live prey. They also apparently cached remains of their prey to eat at a later date; fossils from North Dakota belonging to several small, disassembled Pachycephalosaurs bearing gouge marks matching Occisoraptorid beaks suggest this. While Later Oligocene and Miocene members of this group were rather large animals, Early Oligocene representatives, such as Mesaraptor, were smaller (between 2-3.5m in length). Mesaraptor acrignathus was a 3m long mesocarnivore that would have preyed on small Ornithischians, lizards and mammals, while also supplementing its diet with fruit, fungi and other plant material. A good comparison from our own world might be the Coyote or African Jackals.

Description
Oviraptorosaurs went through a massive diversification event in the Eocene; indeed, the ancestors of most modern representatives of this lineage had appeared by the Late Eocene. However, it was during the Oligocene that these animals really cemented themselves as major components of Eurasian faunal communities. In North America, the Occisoraptorids (descendants of Asian Oviraptorids) first appeared during the Early Eocene as small generalised omnivores but, by the end of the period, had begun to develop heavier skulls and beaks adapted for shearing flesh. The Occisoraptorids survived the Grand Coupre extinction event with minimal losses and continued into the Oligocene with little change. During the Middle Oligocene, the bulky, scavenging Simotyrannosaurids died out, leaving the mid-size predator/scavenger niche with a void to be filled. The already carnivorous Occisoraptorids quickly moved into this niche and became major predators up to 8m in length.

Although they lived alongside Boreoraptorine Dromaeosaurs, the Occisoraptorids avoided competition with them by inhabiting a different ecological niche. Whereas the Boreoraptorines were ambush predators with an exclusively carnivorous diet, their Oviraptorosaur contemporaries were more flexible; they regularly scavenged from carcasses, incorporated the occasional tuber or root into their diet when times got tough as well as taking live prey. They also apparently cached remains of their prey to eat at a later date; fossils from North Dakota belonging to several small, disassembled Pachycephalosaurs bearing gouge marks matching Occisoraptorid beaks suggest this. While Later Oligocene and Miocene members of this group were rather large animals, Early Oligocene representatives, such as Mesaraptor, were smaller (between 2-3.5m in length). Mesaraptor acrignathus was a 3m long mesocarnivore that would have preyed on small Ornithischians, lizards and mammals, while also supplementing its diet with fruit, fungi and other plant material. A good comparison from our own world might be the Coyote or African Jackals.