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 albertensiswas a defining member of the Centrosaurinae. Some have suggested that the genus was really just a synonym to Centrosaurusitself (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. 

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 Albertosaurusbut 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.

Scollard Formation

Maastrichtian

Alberta, Canada

Dinosaurs:

Tyrannosauridae indet.

Albertosaurus sarcophagus

Tyrannosaurus rex

Ornithomimidae indet.

Ricardoestesia gilmorei

Ricardoestesia isosceles

Dromaeosauridae indet.

Dromaeosaurus albertensis

Saurornitholestes langstoni

Paronychodon sp.

Troodon sp.

Caenagnathidae indet.

Ornithischia indet.

Ankylosaurus magniventris

Pachycephalosaurus sp.

Ceratopsidae indet.

Leptoceratops sp.

            Leptoceratops gracilis

Triceratops horridus(including Triceratops albertensis)

Triceratops prorsus

            Torosaurus sp.

Iguanodontia indet.

Thescelosaurus neglectus (including Thescelosaurus edmontonensis)

Parksosaurus warreni

Hadrosauridae indet.

Edmontosaurus annectens

Other Animals:

Myledaphus bipartitus

Cyclurus fragosus

Lepisosteus sp.

Albanerpetontidae indet.

Champsosaurus sp.

Haptosphenus placodon

Stypodontosaurus melletes

Chamops segnis

Odaxosaurus piger

Colpodontosaurus cracens

Parasaniwa wyomingensis

Paraderma bogerti

Crocodylidae indet.

Borealosuchus griffithi

Testudines indet.

Paracimexomys priscus

Cimolomys trochuus

Cimolomys gracilis

Cimolodon nitidus

Ptilodontidae indet.

Mesodma thompsoni

Mesodma formosa

Mesodma hensleighi

Nortedelphys jasoni

Nortedelphys magnus

Aletridelphys florencae

Pediomys elegans

Aletridelphys hatcheri

Leptalestes krejcii

Alphadon sp.

Alphadon marshi

Alphadon wilsoni

Turgidodon rhaister

Didelphodon coyi

Didelphodon vorax

Cimolestes propalaeoryctes

Cimolestes cerberoides

Cimolestes magnus

Batodon tenuis

Schowalteria clemensi

Gypsonictops hypoconus

Gypsonictops illuminatus

Alostera saskatchewanensis

Plants:

Microcarpolithes multistriatus

Costatheca tenuis

Costatheca striata

Dictyothylakos sp.

Erlansonisporites sparassis

Balmeisporites sp.

Spermatites minimus

Azollopsis spinata

Azolla lauta

Azolla filosa

Azolla distincta

Aquilapollenites reticulatus

            Aquilapollenites reductus

            Aquilapollenites cf. attenuatus

            Wodehouseia spinata

Notes:

The Scollard spans the uppermost dinosaur-bearing strata: a final stronghold for dinosaurs. As a Lancian faunal stage, ceratopsians were the predominant herbivore with hadrosaur populations comparatively low. Paul (2010) indicated that the primary Triceratops in the formation was T. prorsus, rather than T. horridus. The member housing the Borealosuchus is assumed to be from the Paleocene (Wu et al. 2001), however, these crocodiles have been found in indisputably Maastrichtian strata so there is no reason to believe this individual was living after the Flood. Additionally, the supposed presence of Albertosaurus in the formation may be a mistake, since albertosaurs are not known to have survived into the Maastritchtian ecological phase. If it was present, it was very rare, and the larger, more powerful Tyrannosauruswould have made life miserable for their smaller relative. Absence of coniferous trees, like sequoias or cypress, may only be a reflection of preservation happenstance or poor sampling. Either way, it seems likely that those trees, characteristic of Maastrichtian habitats, would have been present in the original environment. Certain members of the formation house fantastic arrays of microscopic pollen fossils and, some of these, especially those housing the aquatic azolla varieties, seem preserved separately from the members predominated by vertebrate fossils. Interestingly, these coaly strata tend to overlay the vertebrate fauna (Dawson et al. 1994), indicating that the plants were suspended in deepening water after the animal inhabitants of the region had already been buried. It is even possible that the azolla found the rising waters favourable for reproduction and began to release their pollen in great amounts. Indeed, the most prevalent pollen in the formation is from various forms of Salviniacea (floating ferns). Sometimes the azolla members are considered part of the Paleocene Paskapoo Formation. Because the plants and animals are so separated in the formation it is likely that a very significant portion of the ecosystem is not represented. The insect fauna may be represented by the termite poop fossils of Microcarpolithes (Gunther et Hills 1972). Although once considered an angiosperm plant seed, Microcarpolithesis probably from members of the dry-wood termite families Kalotermitidae or Mastotermitidae (Vasile et al. 2013). The original authors back in 1972 may have been referencing seeds, not insects, but given the confident assignment of other members of the genus to termite families (Colin et al. 2011), it certainly seems possible that M. multistriatusare coprolites. Costatheca has been considered a genus of mollusc (Rozanov et al. 1969 and Sepkoski 2002) or a plant (Kar et al. 2005). There are two species of Costatheca described from the formation (Gunther et Hills 1972). but these are clearly species of plant based on spore fossils. Mammals are surprisingly diverse with a variety of multituberculates, marsupials, and placentals. However, none of these got much bigger than the modern possum or badger and likely spent the majority of their lives in the treetops or undergrowth, hiding from the more dominant dinosaur species until after the end of the Cretaceous. Lizards were common and diverse.

References:

Colin, J.-P., D. Néraudeau, A. Nel, et V. Perrichot. 2011. “Termite coprolites (Insecta: Isoptera) from the Cretaceous of western France: A paleoecological insight.” Revue de micropaléontologie 54: 129-139.

Dawson, F. M., C. G. Evans, R. Marsh, R. Richardson. 1994. “Uppermost Cretaceous and Tertiary Strata of the Western Canada Sedimentary Basin.” In G. D. Mossop and I. Shetsen. Geological Atlas of the Western Canada Sedimentary Basin. Canadian Society of Petroleum Geologists and Alberta Research Council. 387-405.

Gunther, P. R., etL. V. Hills. 1972. “Megaspores and other palynomorphs of the Brazeau Formation (Upper Cretaceous), Nordegg Area, Alberta.” Geoscience and Man 4: 29-48.

Kar, R. K., A. Sahni, K. Ambwani, et D. Dutta. 2005. “Fossil flora (Costatheca and Spermatites) from the Upper Maastrichtian Deccan Intertrappean Beds of India.” Geologica Carpathica 56(2): 149-154.

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

Rozanov, A. Y., V. V. Missarzhevsky, N. A. Volkova, L. G. Voronova, I. N. Krylov, B. M. Keller, I. K. Korolyuk, K. Lendzion, R. Mikhnyar, N. G. Pykhova, et A. D. Sidorov. 1969. “Tommotskiu jarus i problema nizhney granisty kembriya.” Trudy Geoligske Institut Leningrad 206: 1-379.

Sepkoski, J. J. 2002. “A compendium of fossil marine animal genera.” Bulletin of American Paleontology 363: 1-560.

Vasile, S., E. R. Boder, Z. Csiki-Sava, et Z. Szentesi. 2013. “Isopteran trace fossils from the Upper Cretaceous of Central-Eastern Europe.” In D. Tabara (ed). The Ninth Romanian Symposium on Paleontology, Iasi: Abstract Book. Iasi: University of Iasi.

Wu, X.-C., D. B. Brinkman, et R. C. Fox. 2001. “A new crocodilian (Archosauria) from the basal Paleocene of the Red Deer River Valley, southern Alberta.” Canadian Journal of Earth Science 38: 1689-1704.

PHOTO OF THE WEEK: Spangled Cotinga

The spangled cotinga (Cotinga cayana) is a colourful bird from the Amazon River Basin. They primarily eat fruit like all members of the remarkably colourful Cotingidae. I photographed this one at the Calgary Zoo in late August of 2010. The bright blue plumage and purple throat are characteristic of males of this species. Females are a dull grey.