Macelognathus Facts
| Diet | Carnivore |
| Height | 0.2m |
| Length | 0.6m |
| Weight | 2 kg |
| Environment | Land |
| Era | Jurassic |
| Period | Late Jurassic |
| Type | Other |
| Location | North America |

| Diet | Carnivore |
| Height | 0.2m |
| Length | 0.6m |
| Weight | 2 kg |
| Environment | Land |
| Era | Jurassic |
| Period | Late Jurassic |
| Type | Other |
| Location | North America |
Although once classified as a dinosaur, Macelognathus is now known to be a sphenosuchian crocodylomorph - an early relative of modern crocodiles that lived during the Late Jurassic period, approximately 155-149 million years ago. This small prehistoric reptile inhabited what is now Wyoming in North America, sharing its world with famous dinosaurs like Allosaurus and Stegosaurus.
Macelognathus was a diminutive creature, measuring only about 60 centimetres in length and standing roughly 20 centimetres tall at the shoulder. Unlike its massive crocodilian descendants, this ancient reptile was built for life on land rather than in water. Its slender build and relatively long legs suggest it was quite agile, capable of quick movements across the Late Jurassic landscape.
As a carnivore, Macelognathus likely fed on small prey such as insects, small reptiles, and possibly early mammals. Its name, meaning 'long jaw', reflects one of its most distinctive features - an elongated skull that would have been well-suited for snapping up quick-moving prey. The teeth were sharp and pointed, typical of a predatory lifestyle.
The taxonomic journey of Macelognathus demonstrates how our understanding of prehistoric life continues to evolve. Originally described as a turtle due to fragmentary remains, it was later reclassified as a dinosaur before finally being recognised as a crocodylomorph, showing the importance of continued scientific research in palaeontology.
Macelognathus had an unusually elongated skull and jaw, giving it its distinctive appearance and name meaning 'long jaw'. Its slender build and relatively long legs distinguished it from later, more robust crocodylomorphs.
Macelognathus was likely a swift terrestrial hunter, using its agility to chase down small prey across the Late Jurassic landscape. Unlike modern crocodiles, it was fully adapted for life on land rather than aquatic environments.
Macelognathus was first described by Othniel Charles Marsh in 1884. The original fossils were discovered at Morrison Formation, Wyoming, USA.