Episode 450: Triceratops Celebration. The most famous ceratopsian of all time! It may have had horns reaching 5ft (1.5m) long when they had their keratin coverings.

We explore what happened to Ceratops and Diceratops before Triceratops

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The dinosaur of the day: Triceratops

• Chasmosaurine ceratopsian that lived in the Late Cretaceous in what is now North America
• Had a short frill like a centrosaurine but long brow horns like chasmosaurinae, so it was confusing as to which group it belonged
• Now thought to be a chasmosaurinae (only trait it had in common with centrosaurines is the short frill)
• Side note: Zuniceratops is the oldest known ceratopsian with brow horns
• Triceratops had a large bony frill, three horns on the skull
• Had long brow horns
• In 2022, paleontologists studied the skin of Triceratops and keratin of some of its distant relatives, including Psittacosaurus. They found that the keratin covering Triceratops’ brow horns may have made its horns much bigger, possibly almost 5 feet (about 1.5 meters) long.
• Large, walked on four legs
• Lots of similarities to bison and rhinos
• Estimated to be up to 26 to 30 ft (8 to 9 m) long and weigh 5.5 to 9.9 tons
• Had a large skull relative to its body (head was about a quarter of the body length, and in some cases a third)
• One specimen, nicknamed Kelsey, was about 22 to 24 ft (6.7 to 7.3 m) long, with a 6.5 ft (2 m) long skull, and weighed about 6 tons
• Another skull estimated to be 8.2 ft (2.5 m) long
• Lots of skulls found
• More than 50 Triceratops skulls have been found in just the Hell Creek Formation
• Had a robust skeleton/sturdy build
• Walked on all fours
• Debate about whether it sprawled or stood upright
• Latest is that it was somewhere in between, with elbows slightly bent (similar to a modern rhino)
• Had four toes on its hindlimb
• Had five fingers/toes on its front legs
• Fingers pointed out and away from the body
• Triceratops skin has been found. Had large scales
• Skin on a frill also found, and had small polygonal scales
• Had a large beak, with the top formed by the rostral bone (which is what makes it a ceratopsian)
• Had a dental battery
• Probably plucked and grasped food with the beak
• Probably ate fibrous plants, possibly palms, cycads, or ferns
• Frill thought to have been used to help it chew (as an anchor point to help increase the size and power of jaw muscles). But doesn’t seem to have evidence of large muscle attachments on the frill bones
• Had a horn on the snout and two horns above the eyes (brow horns)
• Had a short, bony frill
• As a juvenile, horns were stubs that curved backwards. Mark Goodwin and Jack Horner in 2006 studied 10 skulls, from babies to adults, and found babies had stubs for horns, then as juveniles the horns curve, as subadults they straighten, and as adults they recurve to the front. Juvenile frills start to get ornaments
• Frills and horns may have been for defense, or for identifying each other, attracting mates, or displaying dominance, like modern animals with antlers and horns do
• In 2013 Dave Hone and Darren Naish found that the horns and frills probably weren’t for species recognition, or at least not the primary role. Ceratopsians change quite a bit as they grow up, so it wouldn’t have helped when they were younger
• Frill may have helped regulate body temperature
• Frills and horns may have been to fight predators like Tyrannosaurus
• Lived in swampy areas, as seen in Prehistoric Planet 2
• Lived alongside Tyrannosaurus
• Evidence of Tyrannosaurus and Triceratops fighting (partially healed tyrannosaur tooth marks on a Triceratops brow horn, and horn is broken with new bone growth after the break)
• Triceratops may have fought each other with their horns
• One Triceratops skull found with a hole that looks like it was created by a Triceratops horn
• In 2022, Ruggero D’Anastasio and others found that Big John (found in 2014 in South Dakota) had pathologies from a lesion possibly from another Triceratops horn, and it was in the process of healing when Big John died
• Seems likely Big John lived at least 6 months after the fight
• In 2020, Rina Sakagami and Soichiro Kawabe found Triceratops to have a small olfactory bulb, so sense of smell wasn’t great, and found it could hear low frequencies
• May have held its head about 45 degrees to the ground, which would really show off its horns and frill, and make it easy to graze
• In 2022, Wiemann and others studied the metabolism of dinosaurs, and suggested Triceratops was ectothermic, or more cold-blooded, like modern reptiles
• Covered in episode 414. Recap: ectothermic means an animal can’t regulate its own body temperature, so how warm or cold it is depends on its surroundings. Team figured out how much oxygen an animal used/breathed by testing the fossils. Looked at femurs of 55 animals. Found Triceratops was more ectothermic. Means they were less active, probably basked in the sun, and may have migrated when it got cold
• Unclear if Triceratops traveled in herds
• One bonebed found in Montana but has only juveniles
• In 2012, three Triceratops ranging from juvenile to adult found in Wyoming, and may have been traveling together as a family
• One of the last known non-avian dinosaurs
• Fossils found in the Evanston Formation, Scollard Formation, Laramie Formation, Lance Formation, Denver Formation, Hell Creek Formation
• Triceratops has been found in Montana, South Dakota, Colorado, Wyoming, and in Saskatchewan and Alberta
• Triceratops, the genus name means “three-horned face”
• First described in 1889 by O.C. Marsh
• Many specimens found, ranging from hatchling to adult
• First named fossil now thought to be Triceratops was a pair of horns. George Lyman Cannon found them in Colorado in 1887, and sent them to O.C. Marsh, who thought it belonged to a large bison (named it Bison alticornis)
• In 1887, O.C. Marsh wrote: “This specimen, which may be regarded as the type, indicates one of the largest of American bovines, and one differing widely from those already described. The horn-cores, instead of being short and transverse, as in the existing bisons, are long and elevated, with slender, pointed ends”
• The next year, Marsh named Ceratops but still thought the first horns were from bison
• In 1889, Marsh wrote: “The strange reptile described by the writer as Ceratops montanus proves to have been only a subordinate member of the family. Other remains received more recently indicate forms much larger, and more grotesque in appearance” (Ceratops horridus)
• Then a third, more complete Triceratops skull was found and Marsh changed his mind on the first horns
• Triceratops holotype found in 1888 in the Lance Formation in Wyoming, by John Bell Hatcher. But Marsh named it Ceratops
• A cowboy, Edmund Wilson first saw the skull. He threw a lasso around one of the horns, but it broke off, and the skull fell to the bottom of a cliff. Wilson brought the horn to Charles Guernsey, a fossil collector, who showed it to Hatcher. Marsh told Hatcher to collect the skull
• First called Ceratops horridus. After they found the third horn, Marsh changed it to Triceratops horridus
• The species name “horridus” means “rough” or “rugose” and refers to the rough texture of the fossils
• Hatcher collected 31 Triceratops skulls between 1889 and 1891
• Two species valid today: Triceratops horridus and Triceratops prorsus
• In the past, have had up to 17 species
• Species that are no longer valid include: brevicornis, elatus, calicornis, serratus, flabellatus, obusus, hatecheri, eurycephalus, albertensis, galeus, ingens, maximus, sulcatus, sylvestris
• Scientists eventually thought that there were fewer species, and the differences in skulls was due to individual variation
• John Ostrom and Peter Wellnhofer in 1986 proposed there was only Triceratops horridus, based on there being usually only one or two species of a large animal in a region
• Catherine Forster reanalyzed Triceratops fossils and found there are two species: horridus and prorsus. Also found Nedoceratops to be a separate genus (will get into that)
• In 2009 John Scannella and Denver Fowler agreed
• In 2014, Scannella, Fowler, Goodwin, and Horner studied over 50 skulls of Triceratops and suggested that Triceratops horridus evolved into Triceratops prorsus over a period of 1 to 2 million years (anagenesis)
• Triceratops horridus had a shorter nasal horn, the brow horns faced forward, and had a longer snout
• Triceratops prorsus had a longer nasal horn, the brow horns were pointed more upward, and had a shorter, deeper snout
• Edward Cope also named a couple ceratopsians: Agathaumas and Polyonax, that may actually be Triceratops
• Agathaumas: only found a pelvis, some vertebrae, and a few ribs (only know for sure it’s a ceratopsian)
• Polyonax: only parts of the horns, some vertebrae, and parts of the limbs (also only know for sure it’s a ceratopsian)
• Lots of debates on Torosaurus and Nedoceratops
• Torosaurus had an elongated skull and two holes in the frill
• Torosaurus was named in 1891 based on two skulls
• Torosaurus name means “perforated lizard” and refers to the openings in its frill
• Has been found in as far north as Saskatchewan and as far south as Texas
• Fossils found in Wyoming, Montana, South Dakota, North Dakota, Colorado, Utah, Saskatchewan (possibly also in Texas and New Mexico)
• Not as commonly found as Triceratops
• Had one of the largest skulls
• Had a longer frill than Triceratops, with large openings, and had five or more pairs of hornlets on the back of the frill
• Also had a shorter nose horn
• Fossils first found in 1891, a pair of skulls with long frills and holes in the frills (found in Wyoming by Hatcher)
• Marsh named them Torosaurus latus and Torosaurus gladius
• The species name “latus” means “the wide one” and refers to the frill
• The name “gladius” means “sword”
• Three species: latus, gladius, utahensis (only latus and utahensis still considered valid)
• Torosaurus utahensis originally described as Arrhinoceratops utahensis in 1946 by Charles Whitney Gilmore, based on a frill fragment found in Utah
• Renamed in 1976 to Torosaurus by Douglas Lawson
• Torosaurus had a long frill, and triangular osteoderms on the edge of the frill
• Individual variation in Torosaurus specimens
• In 2009, John Scanella and Jack Horner found Torosaurus was a growth stage of Triceratops. Studied over 50 specimens, including over 30 skulls
• They reclassified Torosaurus as an adult Triceratops
• Ceratopsian skulls have metaplastic bone, which can change length over time and form new shapes
• Lots of variety in Triceratops skulls, and some subadult Triceratops skulls have two thin areas in the frill, in the same spot as the holes in Torosaurus, so it’s possible the holes opened up later to lighten the load of the skull as Triceratops grew longer frills
• In 2011 Jack Horner and Ellen-Therese Lamm studied the frills and found there was lots of resorption
• Also said it was likely that the frill of a mature Triceratops, with the holes, weighed the same as the frill of a large subadult, without the holes
• Andrew Farke said that Triceratops and Torosaurus are distinct. Even though the only difference between them is the frill, he argued that the change in the frill is something not seen in other ceratopsids, and it would involve a lot of changes, including the bone texture reverting from what it’s like as an adult to what it’s like as an immature individual and back to adult (would require too much change to happen)
• Scannella and Horner responded to Farke, and one of their responses was that Torosaurus latus specimens might be an early stage of Triceratops evolving again (part of anagenesis)
• Triceratops skulls do have areas where the bone is thin
• In 2012, Nicholas Longrich and Daniel Field “found that a well-defined sequence of changes exists in horned dinosaurs: development of cranial ornament occurs in juveniles, followed by fusion of the skull roof in subadults, and finally, the epoccipitals, epijugals, and rostral fuse to the skull in adults”. Based on that, found both mature and immature Triceratops and Torosaurus individuals
• Also found that the idea that Torosaurus was Triceratops (the “toromorph” hypothesis), would mean that their fossils should be found in the same locations, that all Torosaurus specimens would be adults and no Triceratops specimens would be very old, and that transitional forms could be found between the two
• Torosaurus and Triceratops did live around the same time and place
• Torosaurus and Triceratops are not in all the same locations, but that could be because not many Torosaurus specimens found compared to Triceratops and there could be a sampling bias
• Longrich studied 36 specimens to check which ones were adults and found that most Torosaurus were old, but there were two exceptions of a young adult and an even younger individual (both had the extended neck frill and openings in the skull—more so than a similarly aged Triceratops). Also found that 10 Triceratops skulls about as old as the oldest Torosaurus specimens
• Found that the thin areas on Triceratops frills could be the beginnings of turning into holes like Torosaurus, but said the structures were in different positions
• In 2013 Leonard Maiorino and others found Triceratops and Torosaurus to be distinct
• Need more fossils
• In 2022, Mallon and others said two specimens found in Canada (Frenchman and Scollard Formations) were subadult Torosaurus, and said it was valid
• Another debate is around Nedoceratops
• Covered Nedoceratops in episode 219
• Lived in the Late Cretaceous in what is now Wyoming, U.S. (Lance Formation)
• Only one skull found, nearly complete
• Found in 1891
• Described by Marsh in his Ceratopsidae monograph, but Marsh died before it was complete, and John Hatcher tried to finish it. But he died in 1904 of typhus, and the paper was incomplete. Richard Swann Lull published it in 1905
• Lull named Hatcher’s description of the skull Diceratops hatcheri (“two horned face”) and published it separately
• In 1933 Lull changed his mind and made it a subgenus of Triceratops: Triceratops hatcheri
• Nedoceratops means “insufficient horned face”
• Name refers to it not having a nasal horn
• Brow horns are almost vertical, and had holes in the frill (some might have been from injury or disease)
• Had a low, rounded nasal horn, different from the larger pointed Triceratops horns (but there is some individual variation)
• In 2011, Scannella and Horner studied Nedoceratops and found it to be part of the Triceratops growth series
• Scannella and Horner suggested Nedoceratops was an intermediate growth stage between Triceratops and Torosaurus and was a synonym of Triceratops
• Nedoceratops has smaller holes in the frill compared to Torosaurus
• Longrich and Fields found the frill holes in the Nedoceratops skull to be a pathology, but thought it was a synonym of Triceratops
• Scannella and Horner suggested the skull lost the nasal horn either when it was alive or when it fossilized
• Andrew Farke said Nedoceratops was its own taxon
• Another case of need more fossils
• Triceratops is in lots of films, on stamps, and other media
• Triceratops is the state fossil of South Dakota and state dinosaur of Wyoming
• Charles Knight painted a mural of a Tyrannosaurus and Triceratops fighting in 1942
• Hatcher the Triceratops at the Smithsonian was the first Triceratops to go on exhibit
• When first going on display in 1905, Hatcher was pieceed together by 10 individuals. Made Hatcher’s head too small for its body, front legs were different lengths, and had the wrong feet
• Originally had Hatcher’s posture with elbows at nearly shoulder level
• In the 1990s Hatcher got updated, and in 2001 put in a more upright position
• Now in the new “Deep Time” exhibit, Hatcher is being eaten by the Nation’s T. rex
• Fun side note: Boston Evening Transcript, 1901, an article titled Making a Triceratops: “Middle-aged persons who were brought up on the schoolbook story of Cuvier’s ability to reconstruct a whole animal of a past era from one bone must prepare to revise their impressions of paleontology”. Article is about Frederic Lucas, from Smithsonian, who illustrates his method of building up a Triceratops, a papier-mache skeleton for the Buffalo Exposition
• Another Triceratops, known as Pops the Triceratops, on display at the Weld County Administrative Building in Colorado (near where it was found, in 1982)
• In 2020, the Melbourne Museum got the world’s most complete Triceratops skeleton, at 87% complete, with a 99% complete skull (which was found in the U.S. in 2014) Paid $3 million for it

Fun Fact:

Despite similarities to rhinos, Triceratops was bigger than an elephant.

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