Megalosauridae
Early giant theropods that shaped dinosaur classification.
Megalosauridae is a family of meat-eating theropod dinosaurs that forms a single evolutionary branch within the group Megalosauroidea. They first appeared in the Middle Jurassic and represent one of the earliest major diversifications of large predatory dinosaurs. As relatively primitive basal tetanurans, the family is split into two main subfamilies—Megalosaurinae and Afrovenatorinae—plus the basal genus *Eustreptospondylus*, which does not clearly belong to either subfamily.
The family’s namesake, *Megalosaurus bucklandii*, was named and described in 1824 by William Buckland based on multiple finds from Stonesfield, Oxfordshire, UK. It was the first dinosaur ever formally described and served as the foundation for the group Dinosauria. *Megalosaurus* is also among the largest known Middle Jurassic carnivorous dinosaurs; its best-preserved femur measures 805 mm, and its estimated body mass is about 943 kg. Although Megalosauridae has traditionally been seen as a European group, with fossils from France and the UK, remains have also been found in North America, Africa, South America, and possibly Asia.
Thomas Huxley named the family Megalosauridae in 1869, but it was not formally defined in the modern phylogenetic sense, and its status has been debated because it long acted as a “waste-basket” for many poorly described or unidentified dinosaur remains. Early on, most large theropods were lumped together, and up to 48 species were placed in the broader clade Megalosauria. Over time, most of those taxa were reassigned, and the definition of Megalosauridae became much narrower. Even so, some controversy persists about whether the group is truly distinct, and its members remain among the most problematic dinosaur taxa. In 2005, paleontologist Paul Sereno questioned the family’s monophyly, rather than simply dismissing it. However, more recent work by Carrano, Benson, and Sampson systematically analyzed all basal tetanurans and concluded that Megalosauridae should stand as its own family. They are generally considered close relatives of the family Spinosauridae.
**Body size**
Like other tetanurans, megalosaurids were bipedal carnivores, but they were especially large, with some members weighing over a tonne.
Quick Facts
- Taxon
- Megalosauridae
- Type Species
- Megalosaurus bucklandii
- Type Species Authority
- Mantell, 1827
Facts from the source article.
Lore & Background
The defining megalosaurid, Megalosaurus bucklandii, was first named and described in 1824 by William Buckland after multiple finds in Stonesfield, Oxfordshire, UK. Megalosaurus was the first formally described dinosaur and was the basis for the establishment of the clade Dinosauria. It is also one of the largest known Middle Jurassic carnivorous dinosaurs, with the best-preserved femur at 805 mm and a proposed body mass of around 943 kg. Megalosauridae has mainly been recognized as a European group of dinosaurs, based on fossils found in France and the UK, but fossils show that the group is also found in North America, Africa, South America and possibly Asia.
Reader's Guide
The family Megalosauridae was first defined by Thomas Huxley in 1869, yet it has been contested throughout history due to its role as a 'waste-basket' for many partially described dinosaurs or unidentified remains. In the early years of paleontology, most large theropods were grouped together and up to 48 species were included in the clade Megalosauria. Over time, most of these taxa were placed in other clades and the parameters of Megalosauridae were narrowed significantly. However, some controversy remains over whether Megalosauridae should be considered its own distinct group, and dinosaurs in this family remain some of the most problematic taxa in all Dinosauria. Some paleontologists, such as Paul Sereno in 2005, have disregarded the group due to its shaky foundation and lack of clarified phylogeny. However, recent research by Carrano, Benson, and Sampson has systematically analyzed all basal tetanurans and determined that Megalosauridae should exist as its own family. They have been generally closely related to the family Spinosauridae.
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