Until very recently the oldest known carrion beetle fossils were 50 million years old. The fossil discoveries coming from Daohugou and Jehol rock deposits in Northeastern China extended our knowledge further back till 160 million years ago. During Jurassic period dinosaur abundance had a cascading influence on animal world. When a dinosaur died its carcass became a protein rich multi-generational feeding island. Insects including carrion beetles most certainly exploited this opportunity. Therefore carrion beetle evolution took a new turn leading to an adaptive radiation. Insect abundance also influenced mammal evolution. The teeth morphology of the newly evolving earliest mammals of this period shows a very clear insect feeding way of life.
One interesting fact about carrion beetles is some families within this insect order care for their young. Conditions favoring evolution of this behavior has been outlined in E. O. Wilson’s seminal book Sociobiology. Parental care should evolve under either very favorable or extremely difficult environments. When resources are rich the competition among the members of the same species gets more intense. In addition, if the predation pressure is intense parental care becomes a necessity. These conditions probably applied to carrion beetles’ ancestral environment. A dead dinosaur is an extremely rich food island. It will quickly become colonized by the beetles and the population will reach its carrying capacity. The island is also a predictable resource attracting insectivorous mammals leading to a build up of predation pressure. There are quite a few examples of parental care among other insects as well.
In marine environments scavengers are quite different. The following video is another time-lapse video shot in icy waters of Antarctica. It shows seastars, urchins and nematode worms scavenging on the carcass of a seal pup.