Nanningosaurus dashiensis

By José Carlos Cortés

Etymology: Nanning City Reptile 

First Described By: Mo et al., 2007 

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Dinosauria, Ornithischia, Genasauria, Neornithischia, Cerapoda, Ornithopoda, Iguanodontia, Dryomorpha, Ankylopollexia, Styracosterna, Hadrosauriformes, Hadrosauroidea, Hadrosauromorpha, Hadrosauridae, Euhadrosauria, Lambeosaurinae 

Status: Extinct

Time and Place: Sometime in the Maastrichtian age of the Late Cretaceous, between 72 and 66 million years ago 

Nanningosaurus is known from the Dashi Site in Guangxi, China 

Physical Description: Nanningosaurus is, sadly, only known from a very incomplete and partial skeleton, which does include parts of the skull and jaws. Thus, it is difficult to say what it would have looked like beyond being a Hadrosaur. It seems most likely that it was a Lambeosaurine, or Hollow-Crested Hadrosaur, though of course we don’t know if it actually had a crest or not. As such, all we can know is that it would have been a fairly bulky animal, covered in scales, with a duck-like beak and potential display or communication structures on its head. It also may have had hooves, like other hadrosaurs, on its front feet. Because of course they did. 

Diet: Being a hadrosaur, Nanningosaurus would have mainly fed upon soft, wet plants, such as those found around or in sources of water. It would have then used its thousands of teeth to mash it up into a paste, to make the leaves easier to swallow. 

Behavior: Obviously, we don’t know a lot about the behavior of Nanningosaurus because, again, we don’t have a lot of fossils of it. As hadrosaurs, they would have been very social animals, living in large herds. It would have taken care of its young, potentially in communal nesting grounds with large mounds to hold the eggs in and rotting vegetation to keep the eggs warm. It probably would have had somewhat complex social displays, potentially using color and sound, in order to communicate with other members of the herd and to find mates. It also may have used this communication to warn the herd of predators, though no predators were found with Nanningosaurus. 

Ecosystem: Nanningosaurus is not known from a very well studied fossil site – it doesn’t even have a formation name! It does seem to have been a muddy environment, indicating some sort of source of fresh water and probable frequent rains. Here, Nanningosaurus lived alongside the titanosaur Qingxiusaurus, which is also only known from limited remains. 

Other: While the exact nature of Nanningosaurus is rather murky, it is a very important fossil discovery – it’s one of the most Southern Asian Hadrosaurs! As such, as we learn more about it, we will be able to piece together the evolutionary puzzle of this wonderful dinosaur group a little clearer. 

~ By Meig Dickson

Sources Under the Cut 

Maiasaura peeblesorum

By José Carlos Cortés

Etymology: Good Mother Reptile 

First Described By: Horner & Makela, 1979 

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Dinosauria, Ornithischia, Genasauria, Neornithischia, Cerapoda, Ornithopoda, Iguanodontia, Dryomorpha, Ankylopollexia, Styracosterna, Hadrosauriformes, Hadrosauroidea, Hadrosauromorpha, Hadrosauridae, Euhadrosauria, Saurolophinae, Brachylophosaurini 

Status: Extinct 

Time and Place: Between 77.2 and 76.3 million years ago, in the Campanian of the Late Cretaceous 

Maiasaura is known from the Upper member of the Two Medicine Formation in Montana 

Physical Description: Maiasaura was a medium-sized hadrosaur – aka, a “duck-billed” dinosaur. Famed for being known from hundreds of individual skeletons, we have a general idea of the appearance of this dinosaur at every stage of its life cycle. Baby Maiasaura were around 0.4 meters in length and were positively tiny in weight, weighing less than 250 kilograms. These babies were adorable in appearance: with large eyes, small heads, and small limbs. The limbs were very weak and skinny at this point in life. Despite this extremely small size, Maiasaura young grew quickly – growing to 1.5 meters in length by the first year, and reaching sexual maturity at about the age of three or so, when they weighed around 1250 kilograms. Full skeletal maturity then came at about five years of age. At this point, Maiasaura were as much as 3000 kilograms in weight, and reaching 9 meters in length. Maiasaura adults were much beefier than the young – with thick, strong hind legs and somewhat more gracile front legs, it was almost as if they had deer front legs and elephant hind legs. The front feet formed hoof-like structures – with the pinky and thumb both sticking out, the middle three fingers were fused together. The hind limbs were typical ornithopod feet, with three toes splayed out like that of a very thick bird. Their tails were thick and muscular, and their torsos also very beefy. They had very thick, muscular necks as well. 

By Ripley Cook

The heads of Maiasaura were rectangular and long, with flattened duck bills in the front. In the jaws, there were rows upon rows of densely packed teeth, forming a single surface. This surface was essentially serrated with the number of teeth packed in there. The upper jaws could then expand, allowing the lower jaws to slide upwards into them, creating a chewing motion. The more duck-like front bill was used to snip off plants and bring them into the jaw. Maiasaura also had a very large nose, forming a sort of lump in the front of the snout – this would have helped keep the head cool, and also allowed Maiasaura to make a variety of calls without a hollow crest attached. Above the eyes the skull of Maiasaura was domed with the brain area. In front of the eyes, on the top of the skull, there was a little ridged crest for display. It is logical to suppose that said crest would be somewhat patterned or even colorful, for display. 

By Nobu Tamura, CC BY 3.0

Scale impressions from Maiasaura are known. Adults of this species were entirely scaley, with almost a pebble-like texture of scales covering the entire body. These small round patches didn’t seem to overlap much, but were densely packed and not leaving much in the way of bare skin showing. Very small ones no longer than 2 millimeters were interspersed with bigger, more hexagonal ones at five to ten millimeters long. It is possible that fuzz would extend between the scales, but they would have looked rather like plants growing between sidewalk scales, and fairly impossible to see ultimately. The back was bumpy from the spine, and rather high over the animal – making Maiasaura itself quite tall. The scales were even bigger on this portion of the animal. Though skin impressions are known from Maiasaura adults and close relatives, baby Maiasaura do not have preserved skin impressions. What this means is that, while it seems very logical they’d also be scaly, there is a possibility they were fluffy to stay warm, given their smaller size. We present one hypothetical reconstruction of such for you all below, with the caveat that it is purely speculation at this time. 

By Diane Ramic

Diet: Maiasaura, like other hadrosaurs, fed mainly on soft, wet vegetation at low and middle levels of browsing (rather more tough, hard, dry vegetation like scrub plants and desert brush). So, it would favor leaves, berries, and more tender shoots, as well as plants in sources of water. 

By Madchester, in the Public Domain

Behavior: Maiasaura was a highly social, active animal – warm blooded in energy levels, these dinosaurs would have spent most of their time, each and every day, wandering around looking for food and socializing with other members of the herd. They spent a good portion of their time taking care of their young, of course, but that was only during the breeding season. Nests were made in large breeding colonies, not unlike their modern bird relatives such as seabirds, with gaps between nests only 7 meters long – less than the length of the adults that had to move between them! Between thirty and forty eggs were laid in a dense spiral pattern, and these eggs were the size of an ostrich’s today. Rotting vegetation was placed upon the nest to keep it warm. The babies, not able to take care of themselves upon hatching, entirely relied on their parents to bring them back chewed up food and look out for their safety. Sadly, most of the young would still die in the first year of life – mainly due to disease and predation, up to 90% of the young would die in the first year of life. Still, the parents did their best – with the young having features associated with cuteness, indicating dependence on the parents for survival until they reached larger sizes. 

By Debivort, CC BY-SA 3.0

Past that point, however, as the young grew faster, they fared better in terms of mortality – dropping down to 12% mortality until reaching old age again. They began to move on their own and keep up with the herd as it moved about. Young Maiasaura would walk on two legs, and as they got heavier they would switch to four, still sometimes only using the hind limbs when needed. Upon reaching sexual maturity at around three years of age, they began to get even bulkier. The Maiasaura would live in herds hundreds of individuals large, which would have been very noisy – using those bulky nostrils to make very loud, differing calls. Come mating time, they would display to each other with the ridges on their heads and other patterns. It is uncertain who was in charge of caring for the young, as sexual dimorphism isn’t seen in the skeletons of Maiasaura – if it was just the mother, both parents, just the father, or even the parents and previous children, we do not know at this time. The herd structure would protect the young, the sick, and the old from predators, and they would probably call to each other to ensure that they stayed safe in the face of predation. That being said, most of the rest of Maiasaura would then die in old age, with the death rate jumping up to 44% at the oldest ages of 12 to 14, when their own weight, slowness, and illness would leave them more vulnerable to predators. 

By Fabrizio De Rossi, retrieved from Earth Archives

Ecosystem: The Two Medicine Formation was one of the most iconic dinosaur ecosystems of all time, sort of a precursor in many ways to the more famous Hell Creek, but with more variety and dinosaur diversity! Here was a very large floodplain, filled with rivers and deltas and associated plantlife on sandy riverbanks. This environment was highly associated with the ever-present Western Interior Seaway, much like the later Hell Creek. It was seasonally arid, with rainshadows from the nearby Cordilleran Highlands, which may have been at least somewhat volcanic. This made the Two Medicine Environment positively volatile – with flash flooding, droughts, dehydration, and volcanic activity all allowing for the animals in this region to be wonderfully preserved (allowing us to know so much about Maiasaura)! Plants would grow very rapidly each wet season, making the area a very lush habitat for about half the year, allowing for all these dinosaurs to congregate here. This environment was filled with conifers and pine trees primarily, though there were also other types of plants as well. There were non-dinosaurs here as well – the pterosaurs Montanazhdarcho and Piksi, the Choristodere Champsosaurus, unnamed crocodylians, lizards like Magnuviator, mammals such as Cimexomys, Paracimexomys and Alphadon, and a wide variety of turtles like Basilemys. 

By Sam Stanton

Still, dinosaurs were the primary feature of the later (Upper) Two Medicine environment where Maiasaura frequented. There were four different types of Ceratopsians: the flat-nosed Achelosaurus, the curved-horned Einiosaurus, the giant-horned Rubeosaurus/Styracosaurus (depending on who you talk to, lumping-wise), and the small herbivore Prenoceratops. Ankylosaurs came in three different varieties – the large-spined but wiggle-taled Edmontonia, and the wide tail-clubbed Dyoplosaurus and Scolosaurus. Other hadrosaurs shared this environment with Maiasaura, like the large-nosed Gryposaurus, the round-crested Hypacrosaurus, and the small pointed crest having Prosaurolophus. There was also the small, active burrower Orodromeus. As for theropods, there were two different raptors – Bambiraptor and Richardoestesia – which would have been major problems for younger Maiasaura and the babies and eggs. The predatory opposite-bird, Gettyia, would have also been a predator of these smaller individauls. The troodontid Saurornitholestes would have been a major danger to these young Maiasaura along with its close cousins. The adults, on the other hand, had not one but two different species of tyrannosaur to contend with: the bulky and rarer Daspletosaurus, and the more slender Gorgosaurus that has been hypothesized to feed more on hadrosaurs than its cousin (though this is under hot debate). In short, this was the place to be to see just how diverse and fascinating non-avian dinosaurs were right at the end of their tenure, and Maiasaura was a major part (if not the most common part) of that ecosystem. 

By Scott Reid

Other: Maiasaura is the closest thing non-avian dinosaurs get to a “model organism” – a creature with enough specimens, research, and data about it to use it as an example for other animals which we know less about. With hundreds of specimens found and counting, we have recorded a complete growth sequence of this dinosaur, knowing what the trajectory of a typical Maiasaura life was like. This is of vital importance, as hadrosaurs were some of the most diverse dinosaurs at the end of the Cretaceous – the end of the time of non-avian forms. It is also fascinating for how much the life history of Maiasaura – a dinosaur not close to being a bird by any stretch of the imagination – is so similar to birds. With similar rapid growth rates as their warm-blooded cousins, and similar nesting and group living strategies, Maiasaura showcases how complex behavior and lifestyles were common over the entirety of the dinosaur group. Maiasaura is also of fundamental importance because, with its discovery and descriptions in the late 1970s, it served with Deinonychus to show how dinosaurs weren’t slow, sluggish, giant lizards – but active, warm-blooded avian precursors. Dinosaurs were active, behaviorally complex, and took care of their young – something that was a truly revolutionary statement before these dinosaurs were named! So, despite not really looking like much, Maiasaura is probably one of the most important dinosaur discoveries ever found. Maiasaura itself is closely related to dinosaurs such as Brachylophosaurus, and is in general part of the “crestless” hadrosaur group, along with the contemporary Gryposaurus and the later Edmontosaurus. 

~ By Meig Dickson

Sources under the Cut 

Angulomastacator daviesi

By José Carlos Cortés

Etymology: Bended Chewer

First Described By: Wagner & Lehman, 2009

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Dinosauria, Ornithischia, Genasauria, Neornithischia, Cerapoda, Ornithopoda, Iguanodontia, Dryomorpha, Ankylopollexia, Styracosterna, Hadrosauriformes, Hadrosauroidea, Hadrosauromorpha, HadrosauridaeEuhadrosauria, Lambeosaurinae

Status: Extinct

Time and Place: All we know is that Angulomastacator lived in the Campanian age, so sometime between 84 and 72 million years ago (though it seems to be around 76 million years ago) 

Angulomastacator is known from the Aguja Formation of Texas 

Physical Description: Angulomastacator was a Lambeosaurine – a duck-billed dinosaur with a hollow crest connected to its nose – known from its jaws. Fascinatingly enough, its jaws were weirdly curved downwards, at a 45 degree angle – unusual for a hadrosaur, or really for any dinosaur. As such, it was probably a very highly specialized herbivore. Unfortunately, without more fossil evidence of Angulomastacator, we cannot be certain of the rest of its morphology; what shape its crest may have been, or size of its body, is uncertain. As a Lambeosaurine, it would have been a rather chunky animal, and facultatively bipedal. It probably would have been of moderate to larger size.

Diet: Angulomastacator would have eaten primarily soft plant matter such as ferns and flowers and fruit, but with its downturned jaw it’s uncertain how its diet would have differed extensively from other hadrosaurs; it’s probable that it would have fed on lower lying vegetation than other hadrosaurs, reaching down into a fern and grabbing the leaves while pulling upwards. 

By Ripley Cook

Behavior: Angulomastacator, as a hadrosaur, would have been extremely social, living in very large and complicated family groups. These groups would have cooperatively taken care of their young in large nesting sites. They probably had hollow crests, which would have made distinctive sounds; though the shape of said crest is uncertain. Finally, that crest would probably have been used in display.

Ecosystem: The Aguja Formation represented a coastal plain environment, associated with a muddy transition going from the ocean to narrow river channels. This was an environment filled with many early flowering plants as they grew along the coast. Here there were many other dinosaurs – ceratopsians such as Agujaceratops and Yehuecauhceratops, ankylosaurs like Edmontonia, the pacycephalosaur Texacephale, and another hadrosaur, Kritosaurus. There were also predators such as Saurornitholestes, and omnivores like Leptorhynchos, which would have been dangers for young Angulomastacator. In addition there were turtles and the extremely big crocodilian Deinosuchus which would have fed on adult Angulomastacator as they passed by sources of water.

Other: Angulomastactor is a rare example of a hollow-crested hadrosaur with an interesting feature that isn’t the crest!

~ By Meig Dickson

Sources under the Cut 

Parasaurolophus

P. cyrtocristatus by Scott Reid

Etymology: Near Crested Reptile

First Described By: Parks, 1922

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Dinosauria, Ornithischia, Genasauria, Neornithischia, Cerapoda, Ornithopoda, Iguanodontia, Dryomorpha, Ankylopollexia, Styracosterna, Hadrosauriformes, Hadrosauroidea, Hadrosauromorpha, HadrosauridaeEuhadrosauria, Lambeosaurinae, Parasaurolophini

Referred Species: P. walkeri, P. tubicen, P. cyrtocristatus

Status: Extinct

Time and Place: Between 76.9 and 73.5 million years ago, in the Campanian age of the Late Cretaceous 

Parasaurolophus was a widespread genus of hadrosaur, living in four of the iconic formations of the Campanian of North America. Parasaurolophus is known from the Lower member of the Dinosaur Park Formation; the Middle member of the Kaiparowits Formation, the Fossil Forest Member of the Fruitland Formation, and the De-na-zin member of the Kirtland Formation. 

Physical Description: Parasaurolophus is an iconic hadrosaur – a group of highly social dinosaurs that were facultatively bipedal, mainly walking on two legs but able to walk on four limbs when necessary (and when moving slower – two legs was more for running). Like other hadrosaurs, while its hand limbs were like those of other ornithopods – kind of bulky, with three toes – its forelimbs were skinny and narrow, culminating in fused fingers that formed a pseudo-hoof structure – essentially, the limbs of hadrosaurs were what you would get if you had a mammal that was front-horse and back-rhino! Roughly speaking anyway. These hands still had their palms facing inwards – it never made “bunny hands” as commonly depicted. It was large and bulky, though how bulky is up to some debate – with some scientists rendering it more slender in the neck and tail regions for more streamlined running; and others rendering it very bulky in the neck and tail, for fat storage and general weight to help it defend itself from predators. Unfortunately, this is one of those speculations that seems unlikely to be solved anytime soon! In addition to that, it had somewhat high neural spines, giving its back even more bulk and muscle mass. Overall, Parasaurolophus was about 9.5 meters long, and weighed 2.5 tonnes – making it a very large hadrosaur in general, with one of the tallest backs of any hadrosaur. 

By Marmelad, CC BY-SA 2.5

Naturally, its bulk and weird proportions aren’t the things that stand out about Parasaurolophus – its crest is. This was a long tube extending off the back of the head, connected to the nose and beak via hollow tubes running from the nostrils through the crest. This crest varied in shape from species to species, with notable extremes – really long and straight, or short and very curved. This shape did not vary based on sex. What the crest was used for, we’ll get into more in the behavior section. In addition it had a large head in general, with a duck-like bill in the front of the mouth, and rows and rows and rows of densely packed teeth. This battery of tooth formed a single surface, kind of like a serrated edge, that helped Parasaurolophus chew! The upper jaw of Parasaurolophus would extend outwards somewhat, allowing the lower jaw to slide into the upper jaw, thus slicing up soft vegetation so it can be easily digested.

Parasaurolophus was externally covered in scales, which were tubercle-like and uniformly spaced out over the entire body. Other details of its coloration and external appearance are not currently known. 

P. walkeri by Leandra Walkers, Phil Senter, and James H. Robins; CC BY 2.5

Diet: Parasaurolophus, like other hadrosaurs, was a low to medium level browser, feeding mainly on soft and wet plants – even those associated with water environments like lakes, swamps, and rivers; though it wouldn’t have lived in the water as was suggested decades ago. As a Lambeosaurine, it was a selective forager, eating just the right plants and fruit – Saurolophines, the non-crested hadrosaurs, were more generalist browsers.

Behavior: Parasaurolophus was a herding animal, living in large social groups that took care of each other and their young. They would have stuck together in these large groups, migrating back and forth extensively along the Western Interior Seaway. Like other hadrosaurs, it would have taken care of its young in large colonies of nests, with parents working together to bring food back to the altricial nestlings. The nests were made in mounds, with vegetation used to keep the eggs warm. The babies, interestingly enough, didn’t have any crests – in fact, baby hadrosaurs more or less looked very similar, with differences between the species coming into play during puberty. These animals first grew rapidly to larger sizes, before growing the crest, leading to an awkward tween stage in which the animal looked like a full-grown Parasaurolophus without the crest. 

P. walkeri by Ripley Cook

This emphasizes something important about Parasaurolophus – sexual communication. The crest, in addition to the function I’ll address shortly, was very much a display structure. That weird shape and differences from species to species emphasized the distinctions between them, allowing for mating partners to identify each other. Brighter colors on the crest would indicate the individual was able to waste resources on color (and, potentially, color that would out them to predators – making them better able to defend themselves, as well) and, thus, a better option for mating. What colors the crests were is uncertain, but given these were herbivores, bright fancy colors brought about from diet are certainly possible – and ones brought about structurally through scales are also in the realm of possibility. While it has been hypothesized that Parasaurolophus had a skin flap between the crest and the neck, this would have severely limited neck flexibility, and seems unlikely.

Now: did the crest have other functions besides display? Absolutely. Right now, the leading hypothesis for the crest is that it was essentially a Shofar (hollow bone used as horn) attached to the noses of Parasaurolophus. This means that Parasaurolophus could breathe in air through the nostrils, send it through the passageways in the crest like some sort of trombone, and blow it back out – making very loud, very eerie, honking sounds. These sounds varied from species to species, both within Parasaurolophus and beyond, as other hadrosaurs also had a variety of hollow crests and tube pathways – and each differently shaped tube would produce a different sound. It’s uncertain what this sound would have been exactly, given we don’t know what – if any – external ornamentation was on the crest that would affect the sound output, but modeling has been done to mimic what it would sound like without any ornamentation, and it’s as creepy and awesome as one would expect:

Parasaurolophus Calls

These calls would have been used in communication between members of the herd, and also for mating calls and warning calls. A variety of sounds could have been made from the crest, allowing for somewhat complex communication. This showcases the sheer diversity of vocal structures evolved in dinosaurs! Only time will tell how many cool sounds and functions these crests in all crested hadrosaurs could have had. 

By Brittany Bostain

Ecosystem: Parasaurolophus lived in a variety of ecosystems, each an iconic fauna of the Campanian of the Late Cretaceous. These environments were all along the Western Interior Seaway, however, there were some notable differences amongst them, since they were at different latitudes and thus experienced variations in water levels and temperature.

The coldest environment, the Dinosaur Park Formation, was where P. walkeri lived. Here, Parasaurolophus lived in a large series of river channels forming very wet floodplains that constantly flooded and very wet in general. This was a very rich environment, filled to the brim with a variety of conifers, horsetails, ferns, and flowering plants. Parasaurolophus lived in the lower section of the formation, which I like to call an Ornithischian Lover’s dream come true. Here, there were ankylosaurs aplenty – Edmontonia, Euoplocephalus, Dyoplosaurus, Platypelta, and Scolosaurus; hadrosaurs like Gryposaurus and Corythosaurus; pachycephalosaurs like Hanssuesia, Stegoceras and Foraminacephale; and ceratopsians like Chasmosaurus, Mercuriceratops, and Spinops. There were non-ornithischians too, of course – the tyrannosaur Gorgosaurus which would have been the biggest predator of Parasaurolophus; the ornithomimosaurs Rativates and Struthiomimus; the raptors Dromaeosaurus and Sauronitholestes that would have hunted the eggs and babies of Parasaurolophus; and the troodontid Stenonychosaurus which would have also been a real pest. Plus there were plenty of non-dinosaurs – sharks, sturgeon fish, gars, and teleosts; bivalves and gastropods; multituberculates, proto-marsupials, and proto-placentals; crocodilians, choristoderes, lizards, turtles, pterosaurs, and even plesiosaurs. 

Kaiparowits Teratophoneus and P. cyrtocristatus, by ДиБгд, in the Public Domain

The more temperate environment, the Kaiparowits Formation, was a very muddy environment, with an extreme number of plants leading it to be called a jungle environment – with a wide diversity of new animals very unique to the ecosystem. Here is where P. cyrtocristatus lived – the weirdest of the three species – along with a lot of other truly weird dinosaurs. In the Middle Unit of the formation, Parasaurolophus lived with the ankylosaur Akainacephalus, the hadrosaur Gryposaurus, the ceratopsians Nasutoceratops and Kosmoceratops, the tyrannosaur Teratophoneus, the ornithomimid Ornithomimus, and the troodontid Talos. Here it was Teratophoneus that would have been the main predator of Parasaurolophus. There was also an enantiornithine, Mirarce, and an Oviraptorosaur, Hagryphus. As for non-dinosaurs, there were plenty of turtles and crocodylomorphs.

Finally, the hotter environments of P. tubicen were similar to each other, with one coming after the other. The Fruitland Formation was slightly earlier, and here Parasaurolophus is known from the later Fossil Forest Member, which was a swampy environment next to the sea, and very warm and forested. Parasaurolophus was joined by the pachycephalosaur Stegoceras, the ceratopsian Pentaceratps, as well as unnamed dromaeosaurs, ornithomimds, troodontids, and tyrannosaurids. The later Kirtland Formation also had Parasaurolophus, in the same area, and the same species, indicating that P. tubicen was largely unaffected by the environmental transition. Parasaurolophus is known here from the lowest De-na-zin Member, which was a series of braided river floodplains and not as muddy as the earlier formation (but still very wet). Here Parasaurolophus was joined by the ankylosaurs Ziapelta and Nodocephalosaurus, the hadrosaurs Naashoibitosaurus Kritosaurus, the pachycephalosaur Sphaerotholus, the ceratopsian Pentaceratops, the titanosaur Alamosaurus, and the raptor Saurornitholestes. 

P. tubicen by José Carlos Cortés

Other: Parasaurolophus was named as such because it was thought to be superficially similar to Saurolophus, a Saurolophine with a non-hollow crest coming off the back of its head; it actually took us a bit to realize “hollow crested hadrosaurs” were a major group!

Species Differences: Parasaurolophus had three species, each somewhat different from the others. P. walkeri comes from the Dinosaur Park Formation, P. tubicen from the Kirtland Formation, and P. cyrtocristatus from the Fruitland and Kaiparowits Formations. This makes P. walkeri the oldest of the three, P. cyrtocristatus the middle species, and P. tubicen the youngest. P. walkeri was relatively average between the two; P. cyrtocristatus had the small, curved crest; and P. tubicen was the largest of the species (with both P. tubicen and P. walkeri have long, trombone-like crests). (Though really all three crests were shofarim).

~ By Meig Dickson

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