Spiclypeus shipporum: a new Ornate Chasmosaurine Ceratopsid From Campanian Cretaceous Montana

Spiclypeus shipporum gen. et sp. nov., a Boldly Audacious New Chasmosaurine Ceratopsid (Dinosauria: Ornithischia) from the Judith River Formation (Upper Cretaceous: Campanian) of Montana, USA

Authors:

Mallon et al

Abstract:

This study reports on a new ceratopsid, Spiclypeus shipporum gen et sp. nov., from the lower Coal Ridge Member of the Judith River Formation in Montana, USA, which dates to ~76 Ma (upper Campanian). The species is distinguished by rugose dorsal contacts on the premaxillae for the nasals, laterally projecting postorbital horncores, fully fused and anteriorly curled P1 and P2 epiparietals, and a posterodorsally projecting P3 epiparietal. The holotype specimen is also notable for its pathological left squamosal and humerus, which show varied signs of osteomyelitis and osteoarthritis. Although the postorbital horncores of Spiclypeus closely resemble those of the contemporaneous ‘Ceratops’, the horncores of both genera are nevertheless indistinguishable from those of some other horned dinosaurs, including Albertaceratops and Kosmoceratops; ‘Ceratops’ is therefore maintained as a nomen dubium. Cladistic analysis recovers Spiclypeus as the sister taxon to the clade Vagaceratops + Kosmoceratops, and appears transitional in the morphology of its epiparietals. The discovery of Spiclypeus adds to the poorly known dinosaur fauna of the Judith River Formation, and suggests faunal turnover within the formation.

Albian Cretaceous Wyoming and Montana had a Diverse Mammal Population

Tribosphenic mammals from the Lower Cretaceous Cloverly Formation of Montana and Wyoming

Authors:

Cifelli et al

Abstract:

We report a diverse assemblage of tribosphenidan mammals from several localities in the Cloverly Formation (Lower Cretaceous, Albian) of Montana and Wyoming. This unit is of historical significance for yielding well-known dinosaurs (e.g., Deinonychus antirrhopus, Tenontosaurus tilletti) and early mammals (e.g., Gobiconodon ostromi, Montanalestes keeblerorum). We provisionally identify 13 taxa (five of which are formally recognized), including Pappotherium pattersoni, a new species of the deltatheroidan Oklatheridium (O. wiblei, sp. nov.), a eutherian (Montanalestes, previously named), and two new basal tribosphenidans (Argaliatherium robustum, gen. et sp. nov., and Carinalestes murensis, gen. et sp. nov.). An unnamed taxon, represented by associated but almost edentulous dentaries, is interpreted to have had four incisors, a single-rooted canine, three premolars, and four molars, indicating that the metatherian tooth formula was established by the Albian. In addition, an indeterminate lower molar fragment preserving twinned talonid cusps and a buccal postcingulid provides the earliest evidence for Marsupialiformes. We also provide a more detailed description of the associated dentaries (holotype) of Montanalestes keeblerorum. The mammalian fauna from the Cloverly Formation shares several taxa with the roughly contemporaneous Trinity Group of Oklahoma and Texas, an observation that also applies to the dinosaur fauna, suggesting some degree of latitudinal homogeneity among described terrestrial vertebrates in this part of the North American Early Cretaceous.

Aquilops americanus: a new Neoceratopsian From Albian Cretaceous Motana

A Ceratopsian Dinosaur from the Lower Cretaceous of Western North America, and the Biogeography of Neoceratopsia

Authors:

Farke et al

Abstract:

The fossil record for neoceratopsian (horned) dinosaurs in the Lower Cretaceous of North America primarily comprises isolated teeth and postcrania of limited taxonomic resolution, hampering previous efforts to reconstruct the early evolution of this group in North America. An associated cranium and lower jaw from the Cloverly Formation (?middle–late Albian, between 104 and 109 million years old) of southern Montana is designated as the holotype for Aquilops americanus gen. et sp. nov. Aquilops americanus is distinguished by several autapomorphies, including a strongly hooked rostral bone with a midline boss and an elongate and sharply pointed antorbital fossa. The skull in the only known specimen is comparatively small, measuring 84 mm between the tips of the rostral and jugal. The taxon is interpreted as a basal neoceratopsian closely related to Early Cretaceous Asian taxa, such as Liaoceratops and Auroraceratops. Biogeographically, A. americanus probably originated via a dispersal from Asia into North America; the exact route of this dispersal is ambiguous, although a Beringian rather than European route seems more likely in light of the absence of ceratopsians in the Early Cretaceous of Europe. Other amniote clades show similar biogeographic patterns, supporting an intercontinental migratory event between Asia and North America during the late Early Cretaceous. The temporal and geographic distribution of Upper Cretaceous neoceratopsians (leptoceratopsids and ceratopsoids) suggests at least intermittent connections between North America and Asia through the early Late Cretaceous, likely followed by an interval of isolation and finally reconnection during the latest Cretaceous.

A Reassessment of Chasmosaurine Ceratopsid Judiceratops tigris From Campanian Cretaceous Montana

A reassessment of the horned dinosaur Judiceratops tigris (Ornithischia: Ceratopsidae) from the Upper Cretaceous (Campanian) of Montana, U.S.A.

Author:

Campbell

Abstract:

udiceratops tigris is a recently described ceratopsid, collected from sediments of the Upper Cretaceous (middle Campanian) Judith River Formation (JRF) of northern Montana, U.S.A. The current diagnosis for this taxon is tentative, as it is based on four fragmentary cranial specimens that have limited anatomical overlap. Although these four specimens were not found associated, they were all collected from the same localized area (Kennedy Coulee). New observations, interpretations, and reconstructions of J. tigris are presented in this study, based on the original assumption that these specimens represent the same taxon. Based on these findings, J. tigris had: elongate postorbital horncores with an autapomorphic ovate (egg-shaped) cross section; squamosals with non-imbricated episquamosals, and an anterolaterally-oriented anteriormost episquamosal; a wide medial parietal bar with an autapomorphic meniscus-shaped cross section; an anteroposteriorly wide posterior parietal bar, and, consequently, reduced parietal fenestrae; and at least four small, low-lying epiparietals on each side of the frill. A phylogenetic analysis incorporating the revised diagnosis of J. tigris supports the previous referral of this taxon to Chasmosaurinae, but missing anatomy prevents an understanding of how J. tigris is related to other chasmosaurines. Judiceratops tigris is retained here as a distinct taxon, and, hence, the oldest known chasmosaurine, but has more in common with other chasmosaurines than was previously thought. Further fossil collecting in the JRF of Montana may produce more complete specimens of J. tigris and provide a means of testing the new reconstructions presented here.

Ursolestes perpetior: a new 'Giant' Purgatoriid Plesiadapiforme From Paleocene Paleogene Montana

A ‘giant’ purgatoriid (Plesiadapiformes) from the Paleocene of Montana, USA: mosaic evolution in the earliest primates

Authors:

Fox et al

Abstract:

Ursolestes perpetior gen. et sp. nov. is a large purgatoriid plesiadapiform primate from the middle/late Puercan (earliest Paleocene) Simpson Quarry, Montana, USA. It differs from Purgatorius Van Valen and Sloan, 1965, the only other known purgatoriid and the oldest discovered primate, in its substantially larger body size as inferred from the dimensions of the known parts of its dentition, while resembling Purgatorius in possessing a large lower canine, unreduced p1, and in the upper molars, a protocone twist and weakly developed postprotocone fold; moreover, the m3 of U. perpetior possesses an expanded, plesiadapiform-like posterior lobe of the talonid that supports the hypoconulid. The large lower canine and the greater development of trenchant molar crests suggest that U. perpetior was more insectivorous, differing appreciably from the omnivorous niche long hypothesized for Purgatorius and purportedly marking the insectivore–primate transition. Hence, U. perpetior adds significant new knowledge regarding the breadth of the adaptive zone occupied by purgatoriids in their position at the very beginnings of primate evolution.

Leaf Mining Insects Went Extinct at the KT/K-Pg Extinction in Montana

After the asteroid impact at the end of the Cretaceous period that triggered the dinosaurs' extinction and ushered in the Paleocene, leaf-mining insects in the western United States completely disappeared. Only a million years later, at Mexican Hat, in southeastern Montana, fossil leaves show diverse leaf-mining traces from new insects that were not present during the Cretaceous, according to paleontologists.

"Our results indicate both that leaf-mining diversity at Mexican Hat is even higher than previously recognized, and equally importantly, that none of the Mexican Hat mines can be linked back to the local Cretaceous mining fauna," said Michael Donovan, graduate student in geosciences, Penn State.

Insects that eat leaves produce very specific types of damage. One type is from leaf miners -- insect larvae that live in the leaves and tunnel for food, leaving distinctive feeding paths and patterns of droppings.

Donovan, Peter Wilf, professor of geosciences, Penn State, and colleagues looked at 1,073 leaf fossils from Mexican Hat for mines. They compared these with more than 9,000 leaves from the end of the Cretaceous, 65 million years ago, from the Hell Creek Formation in southwestern North Dakota, and with more than 9,000 Paleocene leaves from the Fort Union Formation in North Dakota, Montana and Wyoming. The researchers present their results in today's (July 24) issue of PLOS ONE.

"We decided to focus on leaf miners because they are typically host specific, feeding on only a few plant species each," said Donovan. "Each miner also leaves an identifiable mining pattern."

The researchers found nine different mine-damage types at Mexican Hat attributable to the larvae of moths, wasps and flies, and six of these damage types were unique to the site.

link.

Mercuriceratops: A New Chasmosaurine Ceratopsid From Campanian Cretaceous North America

A new chasmosaurine from northern Laramidia expands frill disparity in ceratopsid dinosaurs

Authors:

Ryan et al

Abstract:

A new taxon of chasmosaurine ceratopsid demonstrates unexpected disparity in parietosquamosal frill shape among ceratopsid dinosaurs early in their evolutionary radiation. The new taxon is described based on two apomorphic squamosals collected from approximately time equivalent (approximately 77 million years old) sections of the upper Judith River Formation, Montana, and the lower Dinosaur Park Formation of Dinosaur Provincial Park, Alberta. It is referred to Chasmosaurinae based on the inferred elongate morphology. The typical chasmosaurine squamosal forms an obtuse triangle in dorsal view that tapers towards the posterolateral corner of the frill. In the dorsal view of the new taxon, the lateral margin of the squamosal is hatchet-shaped with the posterior portion modified into a constricted narrow bar that would have supported the lateral margin of a robust parietal. The new taxon represents the oldest chasmosaurine from Canada, and the first pre-Maastrichtian ceratopsid to have been collected on both sides of the Canada–US border, with a minimum north–south range of 380 km. This squamosal morphology would have given the frill of the new taxon a unique dorsal profile that represents evolutionary experimentation in frill signalling near the origin of chasmosaurine ceratopsids and reinforces biogeographic differences between northern and southern faunal provinces in the Campanian of North America.

Anzu wyliei: a Feathered Caenagnathidae Oviraptorosaur (Hell Chicken) From Maastrichtian Cretaceous Hell Creek

A team of researchers has announced the discovery of a bizarre, bird-like dinosaur, named Anzu wyliei, that provides paleontologists with their first good look at a dinosaur group that has been shrouded in mystery for almost a century. Anzu was described from three specimens that collectively preserve almost the entire skeleton, giving scientists a remarkable opportunity to study the anatomy and evolutionary relationships of Caenagnathidae (pronounced SEE-nuh-NAY-thih-DAY)—the long-mysterious group of theropod dinosaurs to which Anzu belongs. The scientific paper describing the discovery appears today in the well-known and freely-accessible journal PLOS ONE.

The three described fossil skeletons of Anzu were unearthed in North and South Dakota, from roughly 66 million-year-old rocks of the Hell Creek Formation, a rock unit celebrated for its abundant fossils of famous dinosaurs such as Tyrannosaurus rex and Triceratops.

The team of scientists who studied Anzu was led by Dr. Matthew Lamanna of Carnegie Museum of Natural History in Pittsburgh. Dr. Lamanna's collaborators include Dr. Hans-Dieter Sues and Dr. Tyler Lyson of the Smithsonian Institution's National Museum of Natural History in Washington, DC, and Dr. Emma Schachner of the University of Utah in Salt Lake City. According to Dr. Lamanna, "Anzu is far and away the most complete caenagnathid that has ever been discovered. After nearly a century of searching, we paleontologists finally have the fossils to show what these creatures looked like from virtually head to toe. And in almost every way, they're even weirder than we imagined."

link.

2nd link.

3rd link.

4th link.

paper link.

Bonebeds may not be Evidence of Gregarious Behavior in Triceratops

Paleobiological implications of a Triceratops bonebed from the Hell Creek Formation, Garfield County, northeastern Montana

Author:

Keenan

Abstract:

Ceratopsid dinosaurs are notable for their common occurrences in bonebeds; however, until recently, these have not been encountered for the chasmosaurine Triceratops. The aim of this investigation is to describe the taphonomy of Quittin' Time (Museum of the Rockies locality HC-430), a Triceratops bonebed in the Hell Creek Formation, Garfield County, Montana. Using site taphonomic descriptions with an evaluation of ontogeny, inferences regarding the paleobiology of this extinct taxon are possible. The locality is associated with abundant organic material, including woody debris, large seeds, and other fragments in isolated silty lenses, all incorporated within a siltstone matrix, indicating preservation within a floodplain environment. Based on the repetition and ontogenetic stages of cranial elements, the minimum number of individuals (MNI) is three. Evidence from the location and taphonomic condition of the bones preserved in close proximity within the same siltstone unit suggests that the individuals—one young adult, one subadult, and a juvenile—likely accumulated during distinct flooding events within a narrow region of the floodplain as a result of “bloat-and-float” transport. The relatively small scale of the bonebed, both in terms of total area and number of individuals, implies that future work on Triceratops sites requires careful scrutiny of cranial elements examined within an ontogenetic framework because they are potentially critical to establishing MNI. Preservation of multiple individuals within the same unit does not necessarily provide evidence of gregarious behavior in Triceratops but rather may be a reflection of site taphonomic history and accumulation processes.

Giant Caenagnathid Oviraptorosaur Found in Maastrichtian Cretaceous Hell Creek Formation

link 1.  link 2. 

Isolated Teeth From hell's Creek Suggest a Higher Theropod Biodiversity Than Previously Thought

Theropod teeth from the upper Maastrichtian Hell Creek Formation “Sue” Quarry: New morphotypes and faunal comparisons

Authors:

1. Terry A. Gates (a)
2. Lindsay E. Zanno (b)
3. Peter J. Makovicky (a)

Affiliations:

a. Field Museum of Natural History, 1400 S Lake Shore Dr., Chicago, IL 60605; Department of Biology, North Carolina State University, Raleigh, NC 27607, USA

b. North Carolina Museum of Natural Sciences, 121 W Jones St., Raleigh, NC 27603; Department of Biology, North Carolina State University, Raleigh, NC 27607, USA

Abstract:

Isolated teeth from vertebrate microfossil localities often provide unique information on the biodiversity of ancient ecosystems that might otherwise remain unrecognized. Microfossil sampling is a particularly valuable tool for documenting taxa that are poorly represented in macrofossil surveys due to small body size, fragile skeletal structure, or relatively low ecosystem abundance. Because biodiversity patterns in the late Maastrichtian of North American are the primary data for a broad array of studies regarding non-avian dinosaur extinction in the terminal Cretaceous, intensive sampling on multiple scales is critical to understanding the nature of this event. We address theropod biodiversity in the Maastrichtian by examining teeth collected from the Hell Creek Formation locality that yielded FMNH PR 2081 (the Tyrannosaurus rex specimen “Sue”). Eight morphotypes (three previously undocumented) are identified in the sample, representing Tyrannosauridae, Dromaeosauridae, Troodontidae, and Avialae. Noticeably absent are teeth attributed to the morphotypes Richardoestesia and Paronychodon. Morphometric comparison to dromaeosaurid teeth from multiple Hell Creek and Lance Formation microsites reveals two unique dromaeosaurid morphotypes bearing finer distal denticles than present on teeth of similar size, and also differences in crown shape in at least one of these. These findings suggest more dromaeosaurid taxa, and a higher Maastrichtian biodiversity, than previously appreciated.

Montana Dueling Dinosaurs Going to Auction

Many paleontologists agree that two fossilized dinosaur skeletons found in the Hell Creek formation in Montana might be a major discovery.

The fossils apparently show two dinosaurs locked together in mortal combat in a Cretaceous-era grave, an example of fighting that could provide a rare window into dinosaur behavior.

Perhaps more important, each of the skeletons may be a new kind of dinosaur — a Nanotyrannus lancensis, a type of pygmy T. rex, and a Chasmosaurine ceratopsian, a close relation of the Triceratops.

But scientists may never know for sure. Going against the hopes of many paleontologists, these two nearly complete skeletons, found by commercial prospectors on a private ranch, are not going directly to a museum for further study. Instead, billed as the “Montana dueling dinosaurs,” they will be auctioned in November by Bonhams in New York, for a projected price of $7 million to $9 million, which would be one of the highest prices ever paid for dinosaur fossils.

“This lines their pockets but hurts science,” Thomas Carr, the senior scientific adviser at the Dinosaur Discovery Museum and director of the Carthage Institute of Paleontology in Wisconsin, said of the sellers, who include the husband-and-wife owners of the ranch and the prospectors, one of whom calls himself the Dino Cowboy.

A museum could still buy the fossils; many were offered them, at an even higher price, in the long, winding road to auction. Or a private buyer could make them available to scientists. It’s the lack of a guarantee that rankles paleontologists. Unlike many countries that carefully control dinosaur fossils found on public and private lands, the United States restricts the collecting of fossils only on public lands. Fossils found on private land, as in this case, belong to the landowner.

As much as this may annoy my paleo friends here, I have to say that I agree the fossils on someone's private land ought to belong to them.  However, I do feel this is a travesty no museum has been able to buy the specimens.  This is a stunning fossil find!  Probably a full skeleton of a Nanotyrannus.  A non-Triceratops (to my untrained eye) ceratopsian from the Hell Creek Formation!  Wow!

If ever there was a call for a kickstarter campaign this would be it.

hmmm.

As if I didn't have enough on my plate...

You know what, if you're interested in helping get a KS campaign going, email me at anzha lyu [at] gmail dont com.

That's Settled: Tyrannosaurus rex Was an Active Predator

Physical evidence of predatory behavior in Tyrannosaurus rex

Authors:

1. Robert A. DePalma II (a)
2. David A. Burnham (b)
3. Larry D. Martin (b)
4. Bruce M. Rothschild (b)
5. Peter L. Larson (c)

Affiliations:

a. Department of Paleontology, Palm Beach Museum of Natural History, Ft. Lauderdale, FL 33306

b. Division of Vertebrate Paleontology, University of Kansas Biodiversity Institute, Lawrence, KS 66045

c. Black Hills Institute of Geological Research, Inc., Hill City, SD 57745

Abstract:

Feeding strategies of the large theropod, Tyrannosaurus rex, either as a predator or a scavenger, have been a topic of debate previously compromised by lack of definitive physical evidence. Tooth drag and bone puncture marks have been documented on suggested prey items, but are often difficult to attribute to a specific theropod. Further, postmortem damage cannot be distinguished from intravital occurrences, unless evidence of healing is present. Here we report definitive evidence of predation by T. rex: a tooth crown embedded in a hadrosaurid caudal centrum, surrounded by healed bone growth. This indicates that the prey escaped and lived for some time after the injury, providing direct evidence of predatory behavior by T. rex. The two traumatically fused hadrosaur vertebrae partially enclosing a T. rex tooth were discovered in the Hell Creek Formation of South Dakota.

REALLY Busy Week for Ceratopsians: Medusaceratops lokii

Michael J. Ryan, Ph.D., a scientist at The Cleveland Museum of Natural History, has announced the discovery of a new horned dinosaur, Medusaceratops lokii. Approximately 20 feet long and weighing more than 2 tons, the newly identified plant-eating dinosaur lived nearly 78 million years ago during the Late Cretaceous period in what is now Montana. Its identification marks the discovery of a new genus of horned dinosaur.

Medusaceratops belongs to the Chasmosaurinae subfamily of the horned dinosaur family Ceratopsidae. The other subfamily is Centrosaurinae. The specimen is the first Campanian-aged chasmosaurine ceratopsid found in Montana. It is also the oldest known Chasmosaurine ceratopsid.

The new dinosaur was discovered in a bonebed on private land located along the Milk River in North Central Montana. Fossilized bones from the site were acquired by Canada Fossil, Inc., of Calgary, Alberta, in the mid-1990s. The company consulted with Ryan and his colleagues to identify material from the site. At first, the scientists could not make a positive identification.

Medusaceratops had giant brow bones more than 3 feet long over each eye, and a large, shield-like frill off the back of its skull adorned with large curling hooks. Medusaceratops lokii means “Loki’s horned-faced Medusa,” referring to the thickened, fossilized, snake-like hooks on the side of the frill. It was named after Loki, the Norse god of mischief, because the new dinosaur initially caused scientists some confusion.

“At first we couldn’t figure out what we had,” said Ryan. “Some of the material looked as if it came from a form related to Centrosaurus, a centrosaurine noted for having short brow horns. The rest of the pieces had giant brow horns similar to Triceratops, a chasmosaurine. That’s one of the problems with bonebeds—even though you can collect a large amount of material, much of it is broken and all of it is disarticulated, so the story is rarely clear cut.”

Eventually Ryan found a complete articulated skull of a centrosaur with long brow horns in southern Alberta of what appeared to be the new animal from Montana, and named it Albertaceratops in 2007. At that time, he assumed he was looking at a stray that had literally crossed the international border millions of years ago.

After reexamining the Montanan material more recently, Ryan realized that at least some of the material in the Montana bonebed was not Albertaceratops. Some of the elements were much larger than any other horned dinosaur from the same time period, including Albertaceratops. And even though Albertaceratops and Medusaceratops are superficially very similar, the shape and number of the hooks and ornaments along the edge of the frill actually puts them in separate horned dinosaur groups, with Medusaceratops being a chasmosaur.

Now we can add Meduaceratops lokii to the mix of new ceratopsians this week. Pix here.

New Anklyosaur From Cretaceous of Montana

A husband and wife team of American paleontologists has discovered a new species of dinosaur that lived 112 million years ago during the early Cretaceous of central Montana.

The new dinosaur, a species of ankylosaur, is documented in the October issue of the Canadian Journal of Earth Sciences. Ankylosaurs are the biological version of an army tank. They are protected by a plate-like armour with two sets of sharp spikes on each side of the head, and a skull so thick that even 'raptors' such as Deinonychus could leave barely more than a scratch.

Bill and Kris Parsons, Research associates of the Buffalo Museum of Science, found much of the skull of the newly described Tatankacephalus cooneyorum resting on the surface of a hillside in 1997. Because the skull was 90% complete, it was possible to justify this fossil as a new species.

"This is the first member of Ankylosauridae to be found within the Early Cretaceous Cloverly Geologic Formation," said Bill Parsons, who characterized the fossil as a transitional evolutionary form between the earlier Jurassic ankylosaurs and the better known Late Cretaceous ankylosaurs.

The skull is heavily protected by two sets of lateral horns, two thick domes at the back, and smaller thickenings around the nasal region. "Heavy ornamentation and horn-like plates would have covered most of the dorsal surface of this dinosaur" said Bill Parsons.

"For years, Bill and Kris have been collecting fossils from a critical time in Earth's history, and their hard work has paid off," said Lawrence Witmer, professor of paleontology at Ohio University who was not involved with this study. "This is a really important find and gives us a clearer view of the evolution of armored dinosaurs. But this is just the first; I'm sure, of what will be a series of important discoveries from this team."

Parsons also illustrated the dermal armour of this new species based on the theory by Museum of the Rockies paleontologist John R. Horner that there was an outer keratinous sheathing on it as found in modern turtle shells and bird beaks. In his new reconstruction, Parsons suggests that Tatankacephalus exhibited complex and colorful patterns rather than the dull appearance suggested in earlier ankylosaur portraits. "According to Horner's theory, many other dinosaurs also had this kind of sheathing and also may have been diversely colored" said Parsons.

As to its name, the broad, short horns on the back of its skull resemble the horns found on a modern buffalo skull and Tatankacephalus loosely translates as 'Buffalo head.' Parsons also noted, "of course any further allusions to the city of Buffalo are completely intentional as well".

AP write up here too.

Any pix?

Triceratops Gregariousness Confirmed?

Until now, Triceratops was thought to be unusual among its ceratopsid relatives. While many ceratopsids—a common group of herbivorous dinosaurs that lived toward the end of the Cretaceous—have been found in enormous bonebed deposits of multiple individuals, all known Triceratops (over 50 in total) fossils have been solitary individuals. But a new discovery of a jumble of at least three juveniles the badlands of the north-central United States suggests that the three-horned dinosaurs were not only social animals, but may have exhibited unique gregarious groupings of juveniles.

"This is very thrilling," says Stephen Brusatte, an affiliate of the American Museum of Natural History and a doctoral student at Columbia University. "We can say something about how these dinosaurs lived. Interestingly, what we've found seems to be a larger pattern among many dinosaurs that juveniles lived and traveled together in groups."

In 2005, Brusatte and colleagues found and excavated a site that contained multiple Triceratops juveniles in 66-million-year-old rocks in southeastern Montana. The geological evidence suggests that at least three juveniles were deposited at the same time by a localized flood, and this suggests that they were probably living together when disaster struck. This find indicates that Triceratops juveniles congregated in small herds, a social behavior increasingly identified in other dinosaur groups, such as Psittacosaurus, a small cousin of Triceratops that lived in Asia.

"We don't know why they were grouped together or how much time they spent together," says Joshua Mathews of the Burpee Museum of Natural History and Northern Illinois University, who led the project. "Herding together could have been for protection, and our guess is that this wasn't something they did full time."

Y'know, I could have sworn that Triceratops was confirmed to have lived in herds if not large ones...but what the heck, maybe not.