Episode 45 is all about Ceratosaurus, a carnivore with a nasal horn.

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In this episode, we discuss:

• The dinosaur of the day: Ceratosaurus, whose name means “horned lizard”
• Lived in the Late Jurassic
• Found in North America and Portugal and Tanzania
• Charles Marsh described the type species in 1884, and Gilmore redescribed the species in 1920
• Type species is Ceratosaurus nasicornis
• Other species include C. magnicornis (named in 2000) and C. dentisculcatus (also 2000)
• C. magnicornis has a rounder horn, but is very similar to C. nasicornis
• C. dentisulcatus is larger (more than 7 m) with an unknown horn shape
• C. dentisculatus may have been twice as big as C. nasicornis
• Fossils found in Portugal have been attributed to C. dentisulcatus
• Paleontologists debate over the validity of both species, saying the differences may be just individuals or differences that come with age
• Type specimen was 18 ft (5.5 m) long, though may not have been fully grown; max length may have been 20 ft (6.1m) long, based on a specimen found in the mid 1960s based on proportions of the holotype
• Type specimen had two left metatarsals fused together, which may mean it had a healed fracture
• Ceratosaurus was very bird like
• 15-20 ft (4.5 to 6m) long and weighed about 0.5 to 1 ton (500 kg to 1 ton)
• Weighed up to 2,160 lb (980 kg)
• Had large jaws, blade like teeth, a blade like horn on its snout and hornlets over its eyes (like Allosaurus)
• Had a row of osteoderms on the middle of its back
• Not sure why it had osteoderms on its back (could be defense against larger predators or against rivals)
• Short, powerful forelimbs
• Short arms with four-fingered hands and sharp claws
• Had a large skull in proportion to body
• Bipedal, s-shaped neck, large tail, heavy bones
• Good eyesight
• Ceratosaurus‘ nasal horn is an extension of the nasal bones on its snout, a fusion of two growths from separate bones (juveniles have beginnings of horn from two bones not fused, so the fusion may indicate reproductive maturity)
• Marsh thought Ceratosaurus‘ nasal horn was a powerful weapon (so did Gilmore), but nowadays scientists think the horn was used for combat among male ceratosaurs (instead of an offensive and defensive weapon) for breeding rights, though other scientists think it was used just for display and may have been brightly colored
• Lived alongside Allosaurus, Torvosaurus, Apatosaurus, Diplodocus, Stegosaurus and Camarasaurus
• Smaller than Allosaurus and Torvosaurus, and probably ate different foods from them, different niche
• Had longer, flexible body, with a tail shaped like a crocodile’s (probably a better swimmer than Allosaurus)
• Marsh theorized Ceratosaurus was a good swimmer, based on its long, thin tail
• Robert Bakker suggested Ceratosaurus went after aquatic prey (fish and crocodiles), though may have also eaten large dinosaurs (scavenged); also found in his study that adults and juveniles sometimes ate together
• May have hunted in groups, may have competed with Allosaurus for stegosaurs, sauropods, iguanodonts
• Had long teeth (when mouth was closed, the teeth could extend below the lower jaw)
• Had a jaw that could slice (instead of crush bone)
• Less common fossils than Allosaurus, though doesn’t necessarily mean it was more rare
• Ceratosaurus fossils were rare (in one quarry there are bones belonging to at least 44 individuals, but only one belonged to a Ceratosaurus)
• Ceratosaurus has been in a few films (D.W. Griffith’s Brute Force from 1914, the first live action film featuring dinosaurs), the Rite of Spring segment of Fantasia, 1940, The Animal World 1956, where a Ceratosaurus fights and kills a Stegosaurus, but then another Ceratosaurus attacks to steal the meal, and both end up falling off a cliff
• Also in the remake One Million Years B.C., a Ceratosaurus fights a Triceratops
• Also seen in The Land that Time Forgot, 1975, and the sequel The People that Time Forgot, 1977
• Also in Jurassic Park III, the TV documentary When Dinosaurs Roamed America and in episodes of Jurassic Fight Club (as a rival to Allosaurus)
• Can see Ceratosaurus at the Natural History Museum of Utah, the Cleveland-Lloyd Dinosaur Quarry and Dinosaur National Monument
• Ceratosaurus is related to abelisaur (like Carnotaurus), and previously Ceratosaurus and abelisaurs and primitive coelophysoids were grouped together as Ceratosauria (theropods closer to Ceratosaurus than to Aves), but more recent evidence shows large distinctions between later ceratosaurs and earlier forms
• Ceratosaurus is the type genus of the family Ceratosauridae
• Ceratosaurids lived in the Jurassic and Cretaceous
• Marsh named the family Ceratosauridae in 1884
• Ceratosaurs competed with other, larger predators
• Two types of Ceratosaurus teeth: one with longitudinal ridges and one with smooth enamel
• Another ceratosaur is Genyodectes serus (not much known about this dinosaur though–no skull found, so unclear if it had a nasal horn)
• Fun Fact: There are 10 types of dinosaurs that have been discovered in Dinosaur National Monument: Ceratosaurus, Torvosaurus, Allosaurus, Apatosaurus, Barosaurus, Camarasaurus, Diplodocus, Haplocanthosaurus, Stegosaurus, Uteodon (yewt-o-don), Dryosaurus