Silphidae is a family of beetles that are known commonly as large carrion beetles, carrion beetles or burying beetles. There are two subfamilies: Silphinae and Nicrophorinae. Nicrophorines are sometimes known as sexton beetles. The number of species is relatively small at around two hundred. They are more diverse in the temperate region although a few tropical endemics are known. Both subfamilies feed on decaying organic matter such as dead animals. The subfamilies differ in which uses parental care and which types of carcasses they prefer. Silphidae are considered to be of importance to forensic entomologists because when they are found on a decaying body they are used to help estimate a post-mortem interval. The family Silphidae belongs to the order Coleoptera. They are commonly referred to as carrion beetles or burying beetles and are usually associated with carrion, fungi, and dung. In the past, members of the family Agyrtidae were included. This family has two subfamilies, Silphinae and Nicrophorinae. The antenna is made up of 11 segments and is capitate (ending in an abruptly capped club) in the Nicrophorinae and has a more gradual club shape in the Silphinae. The subfamilies also differ in behavior. Members of the subfamily Silphinae show little to no care for their young and breed on large carrion. Nicrophorinae breed on small animal carrion and will bury themselves and their food to rear their offspring in a bi-parental manner. There are approximately 183 species in this family, which are found worldwide although they are commoner in temperate regions. Nicrophorus americanus, known as the American burying beetle, is an endangered species. The oldest fossils of silphids are known from the Middle Jurassic (~ 163 million years ago) Daohugou Bed in Northern China. Many Silphidae are flightless although they have wings. This loss is thought to be a result due to the changes in habitat over time. Researchers have found that most flight-capable species in this group feed on vertebrate carcasses, whereas flightless species will feed on soil invertebrates.