Herrerasaurus was about three to five meters long and was, together with the Rauisuchi Prestosuchus , Fasolasuchus and Saurosuchus, the top predator of its time. Staurikosaurus reached a length of three meters and was also carnivorous. Both moved on two legs.
Systematics
The systematic position of the Herrerasauridae has long been controversial. In the past it was often assumed that they were outside the Saurischia and that they were the sister taxons of the dinosaurs ( Ornithischia and Saurischia). In contrast, some scientists see them as the most primitive theropods . Today they are usually placed with the Saurischia, as a sister group of a taxon from Sauropodomorpha and Theropoda. The following cladogram shows the probable family relationships of the Herrerasauridae:
In 2017 a detailed phylogenetic study was published, which revolutionarily proposes a new systematic position. Accordingly, the Herrerasauridae are closer to the Sauropodomorpha than the Theropoda, which in turn have the Ornithischia as a sister group and are united with them in the Ornithoscelida clade . Herrerasauridae and Sauropodomorpha are united in the newly defined clade Saurischia, and the Saurischia together with the Ornithoscelida form the Dinosauria:
↑ Oscar A. Alcober, Ricardo N. Martinez: A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formation of northwestern Argentina. In: ZooKeys. Vol. 63, 2010, ISSN 1313-2970 , pp. 55-81, doi : 10.3897 / zookeys.63.550 .
↑ Fernando E. Novas, Martin D. Ezcurra, Sankar Chatterjee and TS Kutty: New dinosaur species from the Upper Triassic Upper Maleri and Lower Dharmaram formations of central India . In: Earth and Environmental Science Transactions of the Royal Society of Edinburgh . 101, No. 3-4, 2011, pp. 333-349. doi : 10.1017 / S1755691011020093 .
^ MG Baron, Norman DB, Barrett PM: A new hypothesis of dinosaur relationships and early dinosaur evolution . In: Nature . 543, 2017, pp. 501-506. PMID 28332513 .
