Banisterobates boisseaui

Fraser and Olsen 1996

Evidence: A single set of three-toed footprints, with small, inward facing hands preserved by two of the three tracks.

Holotype: VMNH 202

Carnian

Dry Fork Formation

Virginia; USA

Biology: 1 meter long – 1 kilogram

It is practically impossible to guess the size of an animal known from a tiny set of diminutive tracks (less than 2 millimeters in length). The describers even note that they might be confused with the tracks of a horseshoe crab (Fraser and Olsen 1996). The hands are much smaller than the hind feet, however, so it was probably partially bipedal. Assuming a heterodontosaur origin for the tracks, it would imply that even juveniles of the family were at least partially quadrupedal, in spite of the smaller forearms. It would have been an interesting, almost unnatural looking posture, but other tracks presumably belonging to heterodontosaurs have handprints.

Another interesting implication is their presence in a Carnian formation in North America. It is a very deep stratum for any dinosaur, let alone a primarily Jurassic family (Heterodontosauridae).

Evolution:

At first glance, the tracks seemed to me to belong to a theropod, but some small ornithopods have similar tracks (presumably). The handprints are reminiscent of Atreipus, which I once believed was a heterodontosaur, though they seem to be angled inward much more medially. Another possibility is a non-dinosaur dinosauromorph, but it is definitely within that clade, because no other archosaurs have feet that would match the exceptionally bird-like tracks. As Fraser and Olsen (1996) noted, it doesn’t really match any of the better-known dinosauromorphs (lagosuchids), leaving Ornithopoda as the most probable track-maker in this instance. In my own opinion, I would consider it a juvenile heterodontosaur, fabrosaur, or lesothosaur. Unfortunately, there aren’t any bones of these animals present anywhere else in North America, so it might belong in its own family of ornithopods (possibly including some of the Atreipus tracks, since some of those do not appear very theropod-like, as is usually presumed). If this was an ornithopods, it must have adopted a rather hunched, arch-backed posture to produce the tracks. However, we must assume that the tracks were made as the animal moved the way it would if it was a healthy individual, so a long-bodied ornithopods is unlikely. I lean toward the Heterodontosauridae because that family seems to be the best candidate for quadrupedal movement, without looking too unnatural. As a heterodontosaur, it was among the most unique, even as a juvenile, and probably deserves its own subfamily or better.

References:

D’Orazi Porchetti, S., U. Nicosia, P. Mietto, F. M. Petti, and M. Avanzini. 2008.

“Atreipus-like Footprints and their Co-occurrence with Evazoum from the Upper Carnian (Tuvalian) of Trentino-Alto Adige.” Studi Trentini li Scienze Naturali, Acta Geologica 83: 277-287.

Fraser, N. C., and P. E. Olsen. 1996. “A New Dinosauromorph Ichnogenus from the

Triassic of Virginia.” Jeffersoniana 7: 1-17.

Olsen, P. E., and D. Baird. 1986. “The Ichnogenus Atreipus and its significance for

Triassic Biostratigraphy.” In K. Padian (ed.). The Beginning of the Age of Dinosaurs: Faunal Change Across the Triassic-Jurassic Boundary. Cambridge University Press: NY, Ney York. 61-87.

Styracosaurus albertensis

Lambe 1913

Evidence: A few skulls and skeletons, including bonebed remains.

Campanian

Dinosaur Park Formation

Alberta; Canada

Biology: 5.1 meters long – 1.8 tonnes

Because this dinosaur is known from mass graveyards in riverine deposits (Paul 2010; Weishampel et al. 2007), it is possible that they were herding animals. However, Rogers (1990) suggested that the congregational deaths might be due to incidental gatherings caused by drought. Although possibly more impressive than any other ceratopsian adornment, the elaborate horns and frills of Styracosaurus was probably used for the same purposes as other ceratopsian ornaments, such as display, rather than interspecific competition. Of course, the practical use of such lethal spikes as weapons seems evident, should the need arise. The Dinosaur Park Formation itself was host to a huge variety of dinosaurs, including several species of ankylosaurs, ceratopsians, and hadrosaurs. These animals may have competed for space and food with Styracosaurus albertensis. Predators to Styracosaurus may have included a few of the many species of deinonychosaurs that were present in the formation but, more than likely, it was much more concerned with tyrannosaurids. At least two species of these giant theropods could be found in the Dinosaur Park (Daspletosaurus and Albertosaurus) and the strong correlation between ceratopsian numbers and those of tyrannosaurids strongly indicates that the later preyed on the former.

Evolution

Styracosaurus albertensis was a defining member of the Centrosaurinae. Some have suggested that the genus was really just a synonym to Centrosaurus itself (Paul 2010) but this stance is not commonly accepted. Although the central nasal horn certainly equates Styracosaurus with Centrosaurus, its ring of horns around the frill seems to give it some distinction. I am of the opinion that this warrants it’s own genus, but demoting it to a subgenus is not at all out of the question.

References:

Paul, G.S. 2010. The Princeton Field Guide to Dinosaurs. Princeton University Press: Princeton, NJ.

Rogers, R.R. 1990. “Taphonomy of three dinosaur bone beds in the Upper Cretaceous Two Medicine Formation, northwestern Montana: Evidence for drought-related mortality.” PALAIOS 5(5): 394-341.

Dodson, P., C.A. Forster, and S.D. Sampson. 2007. “Ceratopsidae.” The Dinosauria, 2nd Edition. Weishampel, D.B., P. Dodson, and H. Osmólska (ed). University of California Press: Berkeley, CA. 494-513. 

Glossary

I’ve realized that, sometimes, all the lists of scientific names and binomial nomenclature can be a little intimidating to the casual reader. Google, of course, is a great resource to learn about many of these animals, but sometimes extinct genera can be challenging to find online. To help with this, I’ve put together a glossary of names I’ve used for the various formations listed. I’ll be back to update this list periodically.

Alamitophis – a genus of small, boa-like madtsoiid snake.

Albanerpetontidae – superficially salamander-like lissamphibians.

Aletridelphys – a genus of superficially opossum-like peradectid didelphoid marsupial.

Alostera – a genus of zhelestid theriiform eutherian mammal.

Alphadon – a genus of superficially possum-like alphadontid marsupial.

Amblysiphonella – a genus of calcareous demosponge.

Aquilapollenites – a genus of exotic fossil angiosperm plant pollen.

Araceae – arum flowering plants.

Archosauria – archosaur crurotarsans, including crocodiles, dinosaurs, and pterosaurs.

Arecaceae – palm trees.

Arecipites – a genus of palm tree.

Argentodites – a genus of small multituberculate or gondwanatherian mammal.

Asteracanthus – a genus of small hybodontid shark.

Atrochaetetes – a genus of marine demosponge.

Azendohsaurus – a genus of herbivorous archosauromorph reptile.

Azolla – a genus of aquatic floating fern.

Azollopsis – a genus of aquatic floating fern represented by fossil pollen.

Balmeisporites – a genus of aquatic floating fern represented by fossil pollen.

Batodon - a genus of small or medium-sized rodent or possum-like, non-placental cimolestid eutherian mammal.

Boidae – the boa snake family.

Borealosuchus – genus of extinct crocodilian.

Botryococcus – a genus of green algae in the Botryococcaceae family.

Chamops – a genus of slender, omnivorous polyglyphanodontian lizard.

Champsosaurus – a genus of superficially crocodile-like choristoderan diapsid reptile.

Cheirolepidiaceae – a family of extinct conifers superficially resembling palms.

Chelidae – a family of turtles including the mata mata and other snake-necked turtles.

Chiniquodon – a genus of squat, carnivorous cynodont synapsid.

Cimolestes – a genus of small or medium-sized rodent or possum-like, non-placental eutherian mammal.

Cimolodon – a genus of rodent-like multituberculate mammal.

Cimolomys – a genus of rat-like multituberculate mammal.

Classopollis – a genus of the extinct Cheirolepidiaceae conifers.

Coloniatherium – a genus of small dryolestoid mammal.

Colobodontidae – a family of aerodynamically formed perleidiform fish.

Colpodontosaurus – a genus of necrosaurid monitor lizards.

Costatheca – a genus of mollusks with small conical shells or a genus of plant spore.

Crocodylia – crocodilians like alligators and crocodiles.

Crocodylidae – crocodiles.

Crybelosporites – a genus of semiaquatic fern.

Cryptocoelia – a genus of marine demosponge.

Cyathidites – a genus for fossils fern spores.

Cyclurus – a genus of bowfin fish.

Dadadon – a genus of squat, herbivorous traversodontid synapsid.

Dendronella – a genus of red algae.

Dicksonia – a genus of broad-fronded tree ferns.

Dicotyledoneae – plants with broad leaves and branching veins.

Dictyothylakos – a genus of plant spore.

Didelphodon – a genus of semiaquatic alphadontid marsupial.

Elasmosauridae – a family of large, long-necked plesiosaurs.

Enantiornithes – birds with small teeth and wing claws.

Erlansonisporites – a genus of plant spore.

Fungi – mushrooms and their relatives.

Gleicheniidites – a genus for fossil fern spores.

Gypsonictops – a genus of shrew or gerbil-like leptictidan placental mammal.

Haptosphenus – a genus of whiptail lizard.

Hyperodapedon – a genus of hyperodapedontid rhynchosaur with a squat posture and a sharp beak.

Inaperturotetradites – a genus of monocot plant.

Intratriporopollenites – a genus in the Malvaceae family of shrubby plants.

Isalorhynchus – a genus of hyperodapedontid rhynchosaur with a squat posture and a sharp beak.

Jablonskyia – a genus of marine demosponge.

Kannemeyeriiformes – large dicynodont synapsids.

Lepisosteus – a genus of gar fish.

Leptalestes – a genus of opossum-like peradectid metatherian marsupial.

Lugiomarsiglia – a genus of small semi-aquatic fern.

Lygistepollenites – a genus in the Podocarpaceae family of conifers having thin, flat leaves.

Mammalia – mammals.

Margarosmilia – a genus of stony coral.

Madtsoiidae – a family of basal boa-like snakes.

Meiolaniidae – a family of large turtles with heavily armored heads and tails.

Menadon – a genus of squat, herbivorous traversodontid synapsid.

Mesodma – a genus of rodent-like cimolodontan multituberculate mammal.

Metoposauridae – a family of temnospondyl amphibians that appeared like giant, aquatic salamanders.

Metoposaurus – a genus of metoposaurid amphibian that looked like a giant salamander.

Microcarpolithes – a genus of trace fossil interpreted as the coprolites (fossil poop) of termites.

Microchacrydites – a genus in the Podocarpaceae conifers having thin, flat leaves.

Mirasolita – a genus of small semi-aquatic fern.

Molaspora – a genus of small semi-aquatic fern.

Mougeotia – a genus of single-celled green algae in the Zygnemataceae.

Myledaphus – a genus of mackerel shark.

Nelumbo – a genus of lotus flowering plant.

Nelumbonaceae – lotus flowering plants.

Nortedelphys – a genus of opossum-like herpetotheriid metatherian marsupial.

Odaxosaurus – a genus of robust anguid lizard.

Osteopygis – a genus of sea turtles.

Osteichthyes – bony fish.

Paleoazolla – a genus of small aquatic ferns.

Pandaniidites – a genus of arum flowering plant.

Paracimexomys – an extinct genus of rodent-like multituberculate mammal.

Paraderma – an extinct genus of venomous gila monster.

Parasaniwa – a genus of necrosaurid monitor lizards.

Patagoniaemys – a genus of mongolochelyid turtle similar to the Meiolaniidae.

Pediastrum – a genus of green algae in the Hydrodictyaceae.

Pediomys – a genus of superficially opossum-like pediomyid didelphoid marsupial.

Peishanemys – a genus of dermatemydid kinosternoid river turtle.

Peninsulapollis – a genus in the Proteaceae plants.

Phytosauria – superficially crocodile-like crurotarsan archosauriforms.

Phytosauridae- a family of superficially crocodile-like phytosaur crurotarsans.

Podocarpidites – a genus in the conifer family Podocarpaceae having thin, flat leaves.

Procolophonidae – a family of procolophonomorph parareptiles that looked like short, fat lizards.

Pseudosuchia – crocodilians and similar animals.

Ptilodontidae – a family of rodent-like, cimolodontan multituberculate mammals.

Regnellidium – a genus of small, semi-aquatic fern.

Reigitherium – a genus of small, possibly dryolestoid, mammal.

Reptilia – reptiles.

Rhynchosauria – archosauromorph reptiles with squat postures and sharp beaks.

Semionotidae – a family of disk-shaped semionotiform fish.

Serpentes – snakes.

Schowalteria – a genus of large, non-placental, taeniodontan cimolestan eutherian.

Sparganiaceaepollenites – a genus of cattail or bur-reed plant.

Spermatites – a genus of fossil plant spore.

Sphenodontia – lizard-like rhynchocephalian lepidosaurians such as tuatara.

Spirogira – a genus of single-celled green algae in the Zygnemataceae.

Solenopora – a genus of red algae.

Stegocephali – basal tetrapods with flat heads, like Ichthyostega.

Stypodontosaurus – a genus of slender polyglyphanodontian lizard.

Sulcusuchus - a genus of polycotylid plesiosaur.

Synapsida – mammal-like reptiles such as Cotylorhynchus, Dimetrododon, or Gorgonops.

Testudines – turtles and tortoises.

Traversodontidae – a family of herbivorous cynodont synapsids.

Turgidodon – a genus of superficially possum-like alphadontid marsupials.

Typha – the cattail plant.

Uvanella – a genus of marine demosponge.

Wodehouseia – a genus of angiosperm pollen.

Yaminuechelys – a genus of South American-type side-necked turtle.

Zygnema – a genus of single-celled green algae in the Zygnemataceae.

Marnes Irisées Supérieures Formation

Norian

Département de l’Ain, Département du Doubs, and Département du Jura; France

Dinosaurs:

Prosauropoda indet. (including Dimodosaurus poligniensis)

Plateosaurus engelhardti (including Plateosaurus longiceps)

Thecodontosaurus sp.

Theropoda indet.

Other Animals:

            Reptilia indet.

Notes:

Weishampel et al. (2007) tentatively listed Thecodontosaurus for this formation, but that genus has had a very confusing taxonomic history and, because the identification comes from very early in paleontology history (Gervais 1861), it might better be considered an indeterminate prosauropod. Interestingly, Weishampel et al. did not include any theropod remains in their analysis of the formation. Apparently, the only mention of these remains is from early French authors (Chopard 1861). The early date and the lack of reproduction in contemporary writings means this occurrence may not be accurate. If there was a theropod in this formation it was probably a ceratosaur like Liliensternus. The flora, undocumented for this formation, is probably similar to other Triassic habitats.

References:

Chopard, S. 1861. “Decouverte d’ossements fossiles près de Poligny.” Bulletin de la Société d’Agriculture, Sciences et Arts de Poligny (Jura) 2: 200-201.

Gervais, P. 1861. “Présence du genre éteint des Thécodontosaures en France.” Comptes Rendus de l’Académie des Sciences à Paris 52: 347-349.

Weishampel, D. B., P. M. Barrett, R. A. Coria, J. L. Loeuff, X. Xing, Z. Xijin, A. Sahni, E. M. P. Gomani, C. R. Noto. 2007. “Dinosaur Distribution.” In D. B. Weishampel, P. Dodson, and H. Osmólska. The Dinosauria, Second Edition. Berkeley, CA: University of California Press. 517-606.

Albertosaurus sarcophagus

Osborn 1905

Evidence: Well over two dozen partial skulls and skeletons.

Campanian to Maastrichtian

Horseshoe Canyon, Judith River, and Lance Formations

Alberta; Canada: Montana, Wyoming; USA

Biology: 10 meters long – 3 tonnes

Albertosaurus were apparently found in large groups for at least part of their lives. A quarry at Dry Island, Alberta has produced more than two-dozen skeletons of a great variety of ages (Erickson et al. 2006). Because all the individuals in the bone bed are over two years old, Erickson et al. hypothesized that there was an extremely high mortality rate before they reached that age. The range of growth stages at Dry Island has enabled a detailed comparison of juveniles with adults. It seems that, among tyrannosaurids, Albertosaurus sarcophagus was one of the more slow-growing species with only a slightly greater growth spurt during adolescence than Gorgosaurus libratus (Erickson et al. 2004). Although it is evident that all the individuals in the quarry belong to the same species, there is an immense amount of variation, especially in the teeth (Buckley et al. 2010). Currie (1998) believed that this aggregation represented social behaviour in Albertosaurus but other authors have suggested that the presence of their impending doom, such as a flood, was the primary reason so many animals are found together (Roach et Brinkman 2007). It was probably a combination of both factors. Albertosaurus sarcophagus lived a relatively active life that involved interspecific fighting. Some Albertosaurus may have suffered infection from biting one another (Wolff et al. 2009) while most had bone abrasions and breaks as well as tendon pathologies (Bell 2010). These battle scars are evidence that albertosaurs were very social, albeit, not very amiable. The presence of a single very large individual at Dry Island may represent an alpha or senior member of a pack. It is the oldest Albertosaurus known to date at 28 years and 10 meters (Erickson et al. 2006). Because tyrannosaurids grow throughout their lives, giants like this one are possible. The average size of an adult Albertosaurus is closer to 8 meters and 2.5 tonnes (Paul 2010).

Interestingly, the Horseshoe Canyon Formation, were Albertosaurus sarcophagus are primarily found, is also home to Daspletosaurus, another large tyrannosaurid. There has been a lot of speculation over the relationship between these two apex predators since each must have assumed a unique ecological niche. Perhaps the more gracile Albertosaurus pursued faster hadrosaurs and the heavier Daspletosaurus preyed primarily on ceratopsians. In any case, Daspletosaurus ate young hadrosaurs at least some of the time (Varricchio 2001). In all likelihood, both animals probably hunted similar prey and competed violently with one another, just as leopards and lions do in Africa today. The Horseshoe Canyon is unique in its encompassment of Campanian and Maastrichtian fauna. While lambeosaurines are more common in Campanian strata and edmontosaurines in the Maastritchtian, both are present in the Horseshoe Canyon. Perhaps this explains, in part, the coexistence of Daspletosaurus and Albertosaurus in the same ecosystem.

Evolution

A very well known dinosaur, Albertosaurus sarcophagus is the iconic species of its genus and among the best known in its family, the Tyrannosauridae. There is no debate over its placement although the very similar Gorgosaurus libratus is sometimes included in the genus. Among non-Albertosaurinae tyrannosaurids, Daspletosaurus is most similar to A. sarcophagus, as the most basal member of the Tyrannosaurinae (Fiorillo et Tykoski 2014), though an unnamed species of tyrannosaurine from the Dinosaur Park Formation may be even more basal (Loewen et al. 2013). Gorgosaurus may be slightly more basal than A. sarcophagus in the Albertosaurinae.

References:

Bell, P. R. 2010. “Palaeopathological changes in a population of Albertosaurus sarcophagus from the Upper Cretaceous Horseshoe Canyon Formation of Alberta, Canada.” Canadian Journal of Earth Sciences 47: 1263-1268.

Buckley, L. G., D. W. Larson, M. Reichel, et T. Samman. 2010. “Quantifying tooth variation within a single population of Albertosaurus sarcophagus (Theropoda: Tyrannosauridae) and implications for identifying isolated teeth of tyrannosaurids.” Canadian Journal of Earth Sciences 47: 1227-1251.

Currie, P. J. 1998. “Possible evidence of gregarious behavior in tyrannosaurids.” Gaia 15: 271-277.

Erickson, G. M., P. J. Makovicky, P. J. Currie, M. A. Norell, S. A. Yerby, et C. A. Brochu. 2004. “Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs.” Nature 430: 772-775.

Erickson, G. M., P. J. Currie, B. D. Inouye, et A. A. Winn. 2006. “Tyrannosaur Life Tables: An Example of Nonavian Dinosaur Population Biology.” Science 313: 213-217.

Fiorillo, A. R. et R. S. Tykoski. 2014. “A Diminutive New Tyrannosaur from the Top of the World.” PLoS ONE 9(3): e91287.

Loewen, M. A., R. B. Irmis, J. J. W. Sertich, P. J. Currie, et S. D. Sampson. 2013. “Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans.” PLoS ONE 8(11): e79420.

Paul, G. S. 2010. The Princeton Field Guide to Dinosaurs. Princeton, NJ: Princeton University Press.

Roach, B. T., et D. L. Brinkman. 2007. “A Reevaluation of Cooperative Pack Hunting and Gregariousness in Deinonychus antirrhopus and Other Nonavian Theropod Dinosaurs.” Bulletin of the Peabody Museum of Natural History 48(1): 103-138.

Varricchio, D. J. 2001. “Gut contents from a Cretaceous tyrannosaurid: implications for theropod dinosaur digestive tracts.” Journal of Paleontology 75(2): 401-406.

Wolff, E. D. S., S. W. Salisbury, J. R. Horner, D. J. Varricchio. 2009. “Common Avian Infection Plagued the Tyrant Dinosaurs.” PLoS ONE 4(9): e7288.