Guanlong

Type Species: Guanlong wucaii

Classification: Dinosauria – Saurischia – Theropoda – Tetanurae – Coelurosauria – Tyrannosauroidea - Proceratosauridae

Time Period: Late Jurassic

Location: China

Diet: Carnivore

The ten-foot-long theropod Guanlong was discovered in the Shishugou Formation of China and lived during the Oxfordian stage of the Late Jurassic. The Shushugou Formation is peculiar in that it’s comprised of ‘traps’ of vertically-stacked skeletons of numerous non-avian theropods in 3-6 foot deep pits. The pits are filled with a mix of alluvial and volcanic mudstone and sandstone, and they appear to have been created by the trampling and wallowing of large dinosaurs. In the image above, a flock of Guanlong navigate around the sauropods whose heavy pressure created depressions in the soft earth. These deep depressions filled with sediment, creating tarpit-like traps. Theropods mired in these traps would be easy prey for scavengers, and many were trampled underfoot the behemoth sauropods for whom the pits posed no threat. The high quality of preservation indicates a rapid burying of the carcasses, and evidence for scavenging of the bodies is seen in the dispersal of body parts. The area in which these pits existed was largely marshland adjoined by a small volcanic mountain range. Guanlong lived among numerous dinosaurs, small crocodilians, amphibians, and pterosaurs. Guanlong likely hunted smaller dinosaurs, early mammals, and other small animals – and it was likely preyed upon by larger theropods like Yangchuanosaurus. 

Guanlong’s name means ‘five colored crowned dragon,’ and it comes from the elaborate crest on its skull. Two specimens are known, one a juvenile and one an adult. Bone analysis indicates that Guanlong reached adulthood at seven years. The adult specimen died at twelve years of age, and the juvenile died at six years and was still growing. Guanlong had three-fingered hands; the ‘staple’ two-fingered hands of tyrannosaurs wasn’t a staple until the Cretaceous Period. Guanlong’s distinctive crest was made from fused nasal bones. It was thin as a tortilla and just over two inches tall. The crest was filled with air sacs and reminded the discoverers of the ornamental features found on modern cassowaries and hornbills. The crest rose up from the snout between the nostrils and eyes and curved rearwards in an arc above the back of the skull. These crests were certainly for ornamental display purposes, as they were far more delicate and elaborate than those found in dilophosaurid crests (in the case of dilophosaurs, the crests were likely for species-recognition and sexual display). In the juvenile specimen, the crest is restricted to the snout and is thus shorter than the crest of the adult. As Guanlong neared adulthood – and thus sexual maturity – the crest grew to its full size, and in life it was likely colorful to attract mates. Because Guanlong resembles in many ways the Early Cretaceous feathered theropod Dilong, most scientists believe it, too, was covered in feathers. 

Proceratosaurus

Type Species: Proceratosaurus bradleyi

Classification: Dinosauria – Saurischia – Theropoda – Tetanurae – Coelurosauria – Tyrannosauroidea - Proceratosauridae

Time Period: Middle Jurassic

Location: Europe (England)

Diet: Carnivore 

Proceratosaurus was a ten-foot-long theropod that had a slender body and a crest on its snout; the crest likely served display purposes for mating and species recognition. This theropod prowled the wooded islands of prehistoric England, and it lived alongside sauropods such at Cetiosauriscus, the stegosaur Lexovisaurus, the early ornithopod Callovosaurus, and the early ankylosaur Sarcolestes. Though it was originally classified as an ancestor of the Late Jurassic Ceratosaurus, due to the similarity of their snout crests, it’s now consider a coelurosaur, an emerging theropod lineage that overtook the dominant megalosaurs in the Late Jurassic. Not only that, but Proceratosaurus is also considered the earliest tyrannosaur. The Tyrannosauroids emerged in Laurasia in the Jurassic Period, and Proceratosaurus is the earliest known. By the end of the Cretaceous Period, tyrannosauroids were the dominant terrestrial predators in the northern hemisphere. Tyrannosauroid fossils have been discovered in North America, Europe, Asia, South America, and Australia, implying that they diversified and succeeded worldwide. Tyrannosauroids came in many shapes and sizes and are characterized by numerous skeletal features, especially in the skull and pelvis. They emerged in the Jurassic as small theropods with long, three-fingered forelimbs; tyrannosauroids of the Late Cretaceous blossomed to massive sizes and became some of the largest terrestrial predators the planet’s ever seen (these ‘giant’ tyrannosauroids, such as the infamous Tyrannosaurus, lost the long, three-fingered forelimbs to short, two-fingered ones). Primitive feathers have been identified in two species and may have been present in other tyrannosauroids, too. Many species – such as Proceratosaurus – had bony crests in many shapes and sizes, and these likely served for display.