Allosauridae was a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of medium to large sized carnivorous theropod dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s. Members included Saurophaganax

Saurophaganax

Saurophaganax is a genus of allosaurid dinosaur from the Morrison Formation of Late Jurassic Oklahoma . Some paleontologists consider it to be a species of Allosaurus...

, Allosaurus

Allosaurus

Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...

, and the poorly known Epanterias

Epanterias

Epanterias is a dubious genus of theropod dinosaur from the Kimmeridgian-Tithonian-age Upper Jurassic upper Morrison Formation of Garden Park, Colorado. It was described by Edward Drinker Cope in 1878. The type species is Epanterias amplexus. This genus is based on what is now AMNH 5767, parts of...

, which could well be a specimen of Allosaurus

Specimens of Allosaurus

Allosaurus was not only one of the most abundant Late Jurassic dinosaurs, but also one of the best known. Its brain, anatomy and even behaviour were studied more accurate than those of any dinosaur on Earth. Many of its specimens were found: from Utah, Wyoming, Colorado and Montana to Portugal...

. Allosauridae was named by prolific American paleontologist

Paleontology

Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...

 Othniel Charles Marsh

Othniel Charles Marsh

Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...

 in 1878.

The exact number of genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 that can be included here is very debatable and most of the upper Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 and Lower Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 carnosaurs are somewhat closely related to Allosaurus

Allosaurus

Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...

. Whatever the case, allosaurids seemed to be the most successful hunters of their times, outnumbering the Megalosauridae and Ceratosauridae

Ceratosauridae

Ceratosauridae is a family of theropod dinosaurs belonging to the infraorder Ceratosauria. Its type genus, Ceratosaurus, was first found in Jurassic rocks from North America. Ceratosauridae is made up of Ceratosaurus, found in North America, Tanzania, and Portugal, and Genyodectes, from the Late...

, with which they competed for prey. The allosaurids would eventually be succeeded by their close relatives the carcharodontosaurs in the southern hemisphere, and replaced by the coelurosauria

Coelurosauria

Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. In the past, it was used to refer to all small theropods, although this classification has been abolished...

n tyrannosaurids

Tyrannosauridae

Tyrannosauridae is a family of coelurosaurian theropod dinosaurs which comprises two subfamilies containing up to six genera, including the eponymous Tyrannosaurus. The exact number of genera is controversial, with some experts recognizing as few as three...

 in the northern hemisphere, during the Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

Period.