Episode 131 is all about Gryposaurus a saurolophine with a narrow, arching nasal hump, that some have described as like a “Roman nose.”

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In this episode, we discuss:

News:

The dinosaur of the day: Gryposaurus

Name means “hooked nose lizard”, sometimes it’s been translated as “griffin lizard”

Lambe was referencing the nasal arch, which resembled a gryphin (for the name “hooked beak”)

Had a narrow, arching nasal hump, that some have described as like a “Roman nose”

The term “gryposaur” is sometimes used to hadrosaurs with nasal arches

Lived in the Late Cretaceous in North America

Found in Dinosaur Park Formation in Alberta, Canada, Two Medicine Formation in Montana, and Kaiparowits Formation in Utah

Similar to Kritosaurus, and for a while it was thought they were synonyms (long history)

First fossils were collected in 1913 by George Sternberg, from Dinosaur Park Formation in Alberta. Found a skull and partial skeleton

Multiple skulls, some skeletons, and some skin impressions have been found

Lawrence Lambe described Gryposaurus in 1914

A few years before the Gryposaurus find, in 1910, Barnum Brown had found and described a partial skull from New Mexico, and called it Kritosaurus navajovius

Brown’s specimen did not have a snout, so he restored it based on Anatotian (now Edmontosaurus), which had a flat-head

Lambe described Gryposaurus differently (focused on the nasal crest), and in 1916 the Kritosaurus skull was remade to have the nasal arch. Barnum Brown and Charles Gilmore suggested the two were synonyms

This influenced William Park’s decision to name a nearly complete skeleton found in Dinosaur Park Formation Kritosaurus incurvimanus, instead of Gryposaurus incurvimanus (and he let Gryposaurus notabilis stay as its own genus)

Parks considered Gryposaurus to be a junior synonym of Kritosaurus

Hard to compare Kritosaurus incurvimanus and Gryposaurus notabilis because Kritosaurus incruvimanus is missing part of the front of the skull, so we don’t see the full nasal arch

Kritosaurus is only known from partial remians and seem very similar to Gryposaurus (except it lived a little later than Gryposaurus, based on the slightly younger formation where it was found)

In 1942, Lull and Wright published a monograph on hadrosaurs and said Kritosaurus and Gryposaurus were the same

But in the 1990s some scientists questioned Kritosaurus navajovius (limited material compared to other hadrosaurs), so some think the two genera are different

Some scientists, such as Jack Horner, have suggested that Hadrosaurus is the same as Gryposaurus and Kritosaurus. This was a common hypothesis in the 1970s and 80s. But in 1990 Jack Horner changed his mind and said Gryposaurus was its own genera. Most scientists now think that Hadrosaurus and Gryposaurus have differences in their upper arms and iliums

Horner described the specimens of a second species, Gryposaurus This based based on two parts of skeleton that was collected in 1916 for AMNH (also there was bonebed material)

Three valid species: Gryposaurus notabilis, Gryposaurus latidens, Gryposaurus monumentensis (though could be 4-5, depending on who you ask)

Type species is Gryposaurus notabilis

Gryposaurus latidens has an informal name, Hadrosauravus, that was used early on (no longer used)

There’s a possible fourth Gryposaurus species, Gryposaurus alsatei, found in the Javelina Formation

Stephanosaurus marginatus was once considered to be a possible Kritosaurus species (when Kritosaurus and Gryposaurus were considered synonymous), but now it’s considered to be dubious

Jack Horner also created the new combination of Gryposaurus incurvimanus

Gryposaurus has been found in various places including Alberta, Utah, Montana, and possibly Texas, so it had a large geographical range

Gryposaurus lasted for at least 5 million years, which is a lot longer than most other taxon in Hadrosauridae (except Edmontosaurus)

Gryposaurus latidens is from the lower Two Medicine Formation in Montana, and lived about 4 million years before other Gryposaurus species appeared ( notabilis and G. incurvimanus), G. monumentensis is about 1-2 million years younger than G. notabilis and G. incurvimanus

Gryposaurus mounmentensis was named in 2007, by Natural History Museum of Utah paleontologists. Scott Sampson called it the “Arnold Schwarznegger of duck-billed dinosaurs”

Fossils found in Utah, a skull and partial skeleton, were named Gryposaurus monumentensis (found in Grant Staircase-Escalante National Monument). Had a robust skull

Researchers first found Gryposaurus monumentensis in 2003

Gryposaurus monumentensis had thick bones in its skull and limbs

Gryposaurus monumentensis had big jaws, so it could eat tough planet material

Gryposaurus monumentensis had 300 teeth in its mouth for eating, but it had lots of replacement teeth, so at any time it may have had more than 800 teeth

Gryposaurus was bipedal and quadrupedal

Ate a variety of plants, and could eat food on the ground and up to 13 ft (4 m) off the ground

Ground its food (similar to chewing)

Cropped vegetation with its beak, and had cheek-like organ to keep food in its mouth

As Gryposaurus grew, its nasal arch got bigger

The arch was over an enlarged nasal opening, which may have held soft tissue

Nasal arch was probably covered by thick, keratinized skin, or had a cartilaginous extension

Nasal arch may have been for fighting each other, or for species or sexual dimorphism

Nasal arch may also have been used to help push or butt in contests, and it may have had inflatable air sacs (visual and audio signals)

About 30 ft (9 m) long, though one species

Had scales along the midline of its back

Had pyramidal and ridged scales

Saurolophine hadrosaurid (subfamily with hollow crests on their heads)

Gryposaurus was for a while considered to be a hadrosaurine, but then Hadrosaurus was found to be different from other dinosaurs classified as hadrosaurines. Then Hadrosaurus was given a place beneath Hadrosauridae, but hadrosaurinae could no longer be used because it didn’t include Hadrosaurus. So the next oldest genus in that group, Saurolophus, becuase the type genus of Saurolophinae, and now Gryposaurus is considered to be a saurolophine

Probably lived on a floodplain with swamps, ponds, lakes, in a wet and humid climate

May have preferred being by the river

Other dinosaurs that lived in the same time and place include Centrosaurus and Corythosaurus, dromaeosaurids, troodontids, ornithomimids, ankylosaurids, tyrannosaurids (Albertosaurus and Teratophoneus), Parasaurolophus, ceratopsians such as Utahceratops and Nasutoceratops, and oviraptorosaurians such as Hagryphus

Also lived among sharks and rays, frogs, salamanders, turtles, lizards, crocodilians, and early mammals (marsupials and insectivorans)

Where Gryposaurus lived was a relatively small area, and there were other hadrosaur species around at the same time and place. Yet, they didn’t seem to intermingle, and it’s unclear why (since there were no known physical barriers, like mountains, to get in their way). It’s also not clear how such a relatively small area support so many large herbivores. One hypothesis is that hadrosaurs and other large herbivores had slower metabolisms, or maybe there were a large amounts of plants to eat, or the climate in the area, known as “West America” varied across latitudes, so plants in different areas would have been different, and that’s why dinosaurs may not have mixed

Fun Fact:

Japan was connected to the rest of Laurasia for the entire Mesozoic, so dinosaurs could come and go freely

Brief history summarized from Origins of the Japanese Islands: The New “BigPicture” By Gina L Barnes Published in Japan Review: “for 97% of its existence Japan was not an island” First “Japanese” metamorphic rock ~590Ma in the Cambrian (basically bugs, plants) First dinosaurs ~230–240Ma Volcanoes started popping up 146Ma Cretaceous, still stuck to the rest of Asia Japan sea formed between 15–19Ma But parts were still connected periodically as recently as 11,000 years ago The first Mount Fuji didn’t form until 2Ma at the most recent Mount Fuji we know today formed about 10,000 years ago If 230Ma to today was represented as 1 day current Mount Fuji would be around for the last 4 seconds Japan would be an island for maybe 1.5 hours



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