Herrerasaurus was one of the earliest dinosaurs, as well as one of the first theropods to appear. It lived during the


Herrerasaurus ischigualastensis

Herrerasaurus ischigualastensis
Name meaning:                                                              Herrera's lizard
Area:                                                                                     Argentina
Period:                                                                             Late Triassic
Diet:                                                                         meat and corpses
Lenght:                                                                           10-20ft (3-6m)

Height:                                                                                  3,3ft (1m)

Weight:                                                               455-772lb (200-350kg)

Late Triassic period (230 million years ago) in what is now Argentina. Its name means "Herrera's lizard" after the rancher who discovered the fossil. The type and only species, Herrerasaurus uschigualastensis, was later described by Osvaldo Reig in 1963.


Herrerasaurus was a small, lightly built bipedal carnivore, with a long tail, and a relatively small head. Its size estimations variate: the lenght is estimate to range from 3 to 6 meters (10-20ft), being tall 1m (3,3ft) at the hip. Its weight is considered to be at 200-350kg (455-772 lb). They are Carnivores.

It had a long, narrow skull, with some basal characteristics, that linked it to more primitive Archosaurs, such as Euparkeria. Some of this features, not present in more advanced theropods, are: 6 pairs of fenestrae (skull openings), 5 of them being in the upper maxilar, and one of them, being in the lower maxilar, a very tiny fenestrae. 

Furthermore, it had a feature present only in some independent lizards: a flexible joint in the lower joint that allowed the jaw to slide back and deliver a grasping, deadly bite.

Herrerasaurus had short foelimbs, with an unusual, elongated hand. On the hands particularly, it had 5 digits: the
Herrerasaurus SIZE

Herrerasaurus size comparison

thumb and the first two fingers ended in a curve; sharp claw, while the other two were only small stubs, with no claws at all. The forelimbs were strong, suited for bipedal walking and fast running. Its feet had five toes each. However, only three of them supported weight, while the other two really never touched the ground.

Herrerasaurus is something of an enigma in that it displays traits that are found in different groups of dinosaurs, and several traits found in non-dinosaurian archosaurs. Although it shares most of the characteristics of dinosaurs, there are a few differences, particularly in the shape of its hip and leg bones. Its pelvis is like that of saurischian dinosaurs, but it has a bony

Artist's impression of Herrerasaurus

 (where the femur meets the pelvis) that was only partially open. The ilium, the main hip bone, is supported by only twosacrals, a basal trait,.However, the pubis points backwards, a derived trait as seen in dromaeosaurids and birds. Additionally, the end of the pubis has a booted shape, like those in avetheropods; and the vertebral centra has an hourglass shape as found in Allosaurus.

See also:Edit