p. 166 “Although not all of paleopathology concerns itself with dinosaurs—much of it centers on evidence for diseases in pre-historic human remains—this science is being applied enthusiastically to dinosaurs.” Rega, E. 2012. Disease in dinosaurs. In Brett-Surman, M.K., Holtz, T.R., Jr., and Farlow, J.O. (editors), The Complete Dinosaur (2nd Edition). Indiana University Press, Bloomington, Indiana: 667-711.
p. 167 “For example, one specimen of Psittacosaurus from Early Cretaceous rocks of China also, like the Edmontosaurus, has a skin impression associated with its body… .” Lingham-Soliar, T. 2008. A unique cross section through the skin of the dinosaur Psittacosaursus from China showing a complex fibre architecture. Proceedings of the Royal Society of London, B, 275: 775-780.
p. 168 “(This explanation for how dinosaur parts got into marine sediments is nicknamed the ‘bloat-and-float’ hypothesis.)” Martin (2006).
p. 168 “Amazingly, a few of these bones have toothmarks and embedded teeth from scavenging sharks… .” Schwimmer, D.R. 1997. Late Cretaceous dinosaurs in Eastern USA: a taphonomic and biogeographic model of occurrences. 1997 Dinofest International Proceedings: 203-211.
p. 168 “Meanwhile on land, lowly mammals imparted their distinctive incisor incisions on a variety of Late Cretaceous dinosaur bones from Alberta, Canada.” Longrich, N.R., and Ryan, M.J. 2010. Mammalian tooth marks on the bones of dinosaurs and other Late Cretaceous vertebrates. Palaeontology, 53: 703-709.
p. 168 “Carrion beetles, which dine on dead bodies, or termites, which make small pits or tunnels in bones, could have made these.” (1) Britt, B.B., Scheetz, R.D., and Dangerfield, A. 2008. A suite of dermestid beetle traces on dinosaur bone from the Upper Jurassic Morrison Formation, Wyoming, USA. Ichnos, 15: 59-71. (2) Xing, L., Roberts, E.M., Harris, J.D., Gingras, M.K., Ran, H., Zhang, J., Xu, X., Burns, M.E., and Dong, Z. 2013. Novel insect traces on a dinosaur skeleton from the Lower Jurassic Lufeng Formation of China. Palaeogeography, Palaeoclimatology, Palaeoecology, 388: 58-68.
p. 169 “Among my favorite examples of these are big holes in the head shields of Triceratops. When paleontologists first noticed these holes, they were a bit mystified.” Farke et al. (2009).
p. 169 “So paleontologists Andrew Farke, Ewan Wolffe, and Darren Tanke, in an attempt to make sense of these holes, took a closer look at the sizes, shapes, and placements of them… .” Farke et al. (2009).
p. 170 “As many dinosaur fans can relate … the genus name Triceratops, assigned in 1889, translates as ‘three-horned face.’” Marsh, O.C. 1889. Notice of gigantic horned Dinosauria from the Cretaceous. American Journal of Science, 38: 173-175.
p. 170 “Paleontologists are also now sure that Triceratops horns changed in size and shape throughout their lives, becoming more formidable with age.” Horner, J.R., and Lamm, E. 2011. Ontogeny of the parietal frill of Triceratops: a preliminary histological analysis. Comptes Rendus Palevol, 10: 439-452.
p. 171 “Paleontological artist Charles Knight (1874–1953) most famously depicted such a scenario in a 1927 mural… .” Simply titled Tyrannosaurus and Triceratops, it is probably the most iconic of Knight’s gorgeous and influential artworks, and the original is in the Field Museum of Natural History in Chicago, Illinois: http://www. charlesrknight.com/Enlarge.htm?109
p. 171 “Only one tantalizing Triceratops skull tells of a living battle with a Tyrannosaurus, in which one of its brow horns and a squamosal bone were chomped and later healed.” Happ, J. 2008. An analysis of predator-prey behavior in a head-to-head encounter between Tyrannosaurus rex and Triceratops. In Larson, P., and Carpenter, K. (editors). Tyrannosaurus rex, the Tyrant King. Indiana University Press, Bloomington, Indiana: 355-368.
p. 172 “In this role, their large heads would have been quite useful for recognizing the same species and perhaps gender… .” Padian, K., and Horner, J.R. 2011. The evolution of ‘bizarre structures’ in dinosaurs: biomechanics, sexual selection, social selection or species recognition? Journal of Zoology 283: 3-17.
p. 172 “Pachycephalosaurs, such as Pachycephalosaurus, Stegoceras, and others, are relatively rare dinosaurs and only found in Cretaceous Period rocks.” (1) Makovicky, P. 2012. Marginocephalia. In Brett-Surman, M.K., Holtz, T.R., Jr., and Farlow, J.O. (editors), The Complete Dinosaur (2nd Edition). Indiana University Press, Bloomington, Indiana: 527-549. (2) Maryańska, T., Chapman, R.E., and Weishampel, D.B. 2004. Pachycephalosauria. In Weishampel, D.B., Dodson, P., and OsmoÅLlska, H. (editors), The Dinosauria (2nd Edition). University of California Press, Berkeley, California: 464-477.
p. 172 “These skullcaps … can be nearly 25 cm (10 in) thick. They are composed of parietals and closely associated skull bones… .” Makovicky (2012).
p. 173 “Nearly everybody agrees that these robust skulls must have been used for butting… .” Makovicky (2012).
p. 174 “In 2011, two paleontologists, Eric Snively and Jessica Theodor, had head-butting in mind… .” Snively, E., and Theodor, J.M. 2011. Common functional correlates of head-strike behavior in the pachycephalosaur Stegoceras validum (Ornithischia, Dinosauria) and combative artiodactyls. PLoS ONE 6(6): e21422. doi:10.1371/journal. pone.0021422.
p. 174 “They then repeated their analysis on three species of modern mammals that habitually head-smash one another… .” Snively and Theodor (2011).
p. 175 “In 2012 … two other paleontologists—Joseph Peterson and Christopher Vittore—scrutinized a Pachycephalosaurus skull… .” Peterson, J., and Vittore, C. 2012. Cranial pathologies in a specimen of Pachycephalosaurus. PLoS ONE, 7(4): doi: 10.1371/journal.pone.0036227.
p. 176 “In a follow-up study published in 2013, Peterson and two other paleontologists found many more examples, verifying the previous study.” Peterson, J.E., Dischler, C., and Longrich, N.R. 2013. Distributions of cranial pathologies provide evidence for head-butting in dome-headed dinosaurs (Pachycephalosauridae). PLoS ONE 8(7): e68620; doi: 10.1371/journal.pone.0068620.
p. 176 “One is of injured but healed bony tissue in a few tail spikes of Stegosaurus.” Carpenter, K., Sanders, F., McWhinney, L.A., and Wood, L. 2005. Evidence for predator-prey relationships: examples for Allosaurus and Stegosaurus. In Carpenter, K. (editor), The Carnivorous Dinosaurs. Indiana University Press, Bloomington, Indiana: 325-350.
p. 177 “Another is of a hole in a tail vertebra of an Allosaurus, but one that probably healed around a piece of a Stegosaurus tail spike, an unwanted souvenir.” Carpenter et al. (2005).
p. 177 “Paleontologists … had figured that stegosaur tail spikes were used for self-defense, but lacked further confirmation until … 2001 (broken spikes) and 2005 (a healed hole in the bone of a predator).” McWhinney, L.A., Rothschild, B.M., and Carpenter, K. 2001. Posttraumatic chronic osteomyelitis in Stegosaurus dermal spikes. In Carpenter, K. (editor). The Armored Dinosaurs. Indiana University Press, Bloomington, Indiana: 141-156.
p. 177 “Nicknamed ‘Big Al’ and studied by paleontologist Rebecca Hanna in the 1990s, this Allosaurus was unusual in two ways… .” Hanna began reporting on “Big Al” in the late 1990s at professional meetings, and the full results were summarized in her 2002 paper: Hanna, R.R. (2002). Multiple injury and infection in a sub-adult theropod dinosaur (Allosaurus fragilis) with comparisons to allosaur pathology in the Cleveland-Lloyd Dinosaur Quarry Collection. Journal of Vertebrate Paleontology, 22: 76-90. I also recommend checking out a still-informative and entertaining BBC documentary featuring Hanna talking about this Allosaurus, initially titled The Ballad of Big Al (2000).
p. 177 “One of the reasons for this may be an easy one: Coelophysis was a much smaller dinosaur than Allosaurus. …” Holtz et al. (2012).
p. 178 “As elaborated in a previous chapter, if a large two-legged dinosaur tripped, both its greater weight and height would conspire against it… .” Farlow et al. (1995).
p. 180 “For example, a few smaller theropods, such as the Late Cretaceous theropods Velociraptor and Saurornitholestes, had thin, curved, and beautifully serrated teeth.” A good summary o
f theropod tooth shapes and their inferred functions is in: Fastovsky, D.E., and Weishampel, D.B. 2009. Dinosaurs: A Concise Natural History. Cambridge University Press, Cambridge, U.K.: 379 p.
p. 180 “Tooth forms even varied within the same dinosaur, a condition called heterodonty (‘different teeth’).” Martin (2006).
p. 181 “But if you looked deeper into its mouth, say, while being eaten, you would see that the teeth in the front curve more toward the rear of the mouth… .” Reichel, M. 2012. The variation of angles between anterior and posterior carinae of tyrannosaurid teeth. Canadian Journal of Earth Sciences, 49: 477-491.
p. 181 “Certain theropods had an exact number of teeth per tooth row, but that number could also be divided into two parts… .” Reichel (2012).
p. 182 “These marks would have been made by a pulling, lateral movement, so they would be shallow, long grooves on a bone surface… .” Jacobsen, A.R., and Bromley, R.G. 2009. New ichnotaxa based on tooth impressions on dinosaur and whale bones. Geological Quarterly, 53: 373-382.
p. 182 “Because this action would have been more perpendicular to the bone surface, these puncture toothmarks will be deeper… .” Jacobsen, A.R. 1998. Feeding behaviour of carnivorous dinosaurs as determined by tooth marks on dinosaur bones. Historical Biology, 13: 17-26.
p. 182 “Although dinosaur toothmarks were first interpreted as trace fossils near the start of the 20th century… .” Matthew, W.D. 1908. Allosaurus, a carnivorous dinosaur and its prey. American Museum Journal, 8: 2-5.
p. 182 “What made them think these toothmarks belonged specifically to T. rex stemmed from a combination of size, shape, place, and time.” Erickson, G.M., Van Kirk, S.D., Su, J., Levenston, M.E., Caler, W.E., and Carter, D.R. 1996. Bite force estimation for Tyrannosaurus rex from tooth-marked bones. Nature, 382: 706-708.
p. 183 “These artificial teeth were then used to imitate a tyrannosaur bite, but one in which the force exerted by each ‘bite’ could be measured.” Erickson et al. (1996).
p. 184 “Bite-force estimates came out to 6,400 to 13,400 N, which at the time were greater than those known for any living animal… .” Erickson et al. (1996).
p. 184 “In later experiments done on modern alligators and crocodiles, Erickson and other researchers found the largest American alligators (Alligator mississippiensis) had bite forces… .” Erickson, G.M., Lappin, A.K., and Vliet, K.A. 2003. The ontogeny of bite-force performance in American alligator (Alligator mississippiensis). Journal of Zoology, 260: 317-327.
p. 184 “(It was not too surprising, then, when paleontologists later found toothmarks attributable to Deinosuchus in dinosaur bones.)” Rivera-Sylva, H.E., Frey, E., and Guzman-Gutierrez, J.R. 2009. Evidence of predation on the vertebra of a hadrosaurid dinosaur from the Upper Cretaceous (Campanian) of Coahuila, Mexico. Carnets de Géologie [Notebooks on Geology], Letter 2009/02: 1-6.
p. 184 “This gruesome idea came about when Denver Fowler and several other paleontologists noticed, while looking at Triceratops bones from the Late Cretaceous of Montana… .” Fowler et al. (2012).
p. 186 “When paleontologist Ken Carpenter took a close look at this oddity, he saw signs of healing around the bone… .” Carpenter, K. 2000. Evidence of predatory behavior by carnivorous dinosaurs. Gaia, 15: 135-144.
p. 186 “Since Carpenter’s study, other healed toothmarks found in Edmontosaurus bones, either attributed to T. rex or Albertosaurus, have both affirmed… .” The most recent article dealing with tyrannosaurids munching hadrosaurs, which includes references to other interpreted incidents, is: DePalma, R.A., Burnham, D.A., Martin, L.D., Rothschild, B.M., and Larson, P.L. 2013. Physical evidence of predatory behavior in Tyrannosaurus. Proceedings of the National Academy of Sciences, 110: 12560-12564.
p. 186 “So this is exactly how three paleontologists—Ray Rogers, David Krause, and Kristi Rogers—discerned that Majungasaurus, a large theropod from Late Cretaceous rocks of Madagascar, was a cannibal.” Rogers, R.R., Krause, D.W., and Rogers, K.C. 2003. Cannibalism in the Madagascan dinosaur Majungatholus atopus. Nature, 422: 515-518.
p. 187 “Komodo dragons, crocodilians (including alligators), big cats such as lions and tigers, and bears are among the large predators that will eat their own species.” Fox, L.R. 1975. Cannibalism in natural populations. Annual Reviews of Ecology and Systematics, 6: 87-106.
p. 187 “Apparently so, as its rocks show the region was semi-arid while dinosaurs lived there, but with pronounced wet-dry cycles.” Rogers, R.R., Krause, D.W., Rogers, K.C., Rasoamiaramanana, and Rahantarisao, L. 2007. Paleoenvironment and paleoecology of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. Journal of Paleontology, 27, Supplement 2 (Special Issue, Memoir 8): 21-31.
p. 188 “One of the more compelling pieces of evidence for droughts in this area during the Cretaceous comes from other trace fossils, namely lungfish burrows.” Marshall, M.S., and Rogers, R.R. 2012. Lungfish burrows from the Upper Cretaceous Maevarano Formation, Mahajanga Basin, Northwestern Madagascar. Palaios, 27: 857-866.
p. 188 “In a 2010 study conducted by Nicholas Longrich and three other paleontologists, they examined T. rex bones in museum… .” Longrich, N.R., Horner, J.R., Erickson, G.M., and Currie, P.J. 2010. Cannibalism in Tyrannosaurus rex. PLoS One, 5(10): e13419. doi:10.1371/journal. pone.0013419.
p. 189 “This idea, first proposed by paleontologists Darren Tanke and Phil Currie in 1998, was based on healed bite marks they noted in skulls… .” Tanke, D.H., and Currie, P.J. 1998. Head-biting behavior in the theropod dinosaurs: paleopathological evidence. Gaia, 15: 167-184.
p. 190 “These scratches tell you that the hadrosaur moved its upper jaws out and to the sides while the lower jaw stayed put.” Williams, V.S., Barrett, P., and Purnell, M.A. 2009. Quantitative analysis of dental microwear in hadrosaurid dinosaurs, and the implications for hypotheses of jaw mechanics and feeding. Proceedings of the National Academy of Sciences, 106: 11194-11199.
p. 190 “These marks, called microwear, were scored on dinosaur teeth when they chewed plants containing silica or plants with grit on them.” Fiorillo, A.R. 1998. Dental microwear patterns of the sauropod dinosaurs Camarasaurus and Diplodocus: evidence for resource partitioning in the Late Jurassic of North America. Historical Biology, 13:1-16.
p. 191 “Phytoliths are common in many plants today, especially monocotyledons, which include all grasses, orchids, bamboo, palm trees, and many others.” Piperno, D.R. 2006. Phytoliths: A Comprehensive Guide for Archaeologists and Paleoecologists. Rowman Altamira, Lanham, Maryland: 238 p.
p. 191 “Monocotyledons also got their start in the middle of the Mesozoic Era.” Daghlian, C.O. 1981. A review of the fossil record of monocotyledons. The Botanical Review, 47: 517-555.
p. 192 “Paleontologists who studied microwear in Edmontosaurus found out that this dinosaur… .” Williams et al. (2009).
p. 192 “But anatomical studies done on some sauropods now imply that some of these lengthy necks were maybe better suited for sweeping large areas—back and forth—across fields of low-lying vegetation.” This research on sauropod-neck flexibility has been going on for a while, but the latest paper summarizing it (along with new findings) is: Cobley, M.J., Rayfield, E.J., and Barrett, P.M. 2013. Intervertebral flexibility of the ostrich neck: implications for estimating sauropod neck flexibility. PLoS One, 8: e72187. doi:10.1371/journal. pone.0072187
CHAPTER 7: WHY WOULD A DINOSAUR EAT A ROCK?
p. 195 “… the Morrison Formation was rightly celebrated elsewhere in the western U.S. for yielding some of the best-loved of all dinosaurs… .” Foster, J. 2007. Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press, Bloomington, Indiana: 416 p.
p. 196 “‘Gastrolith’ literally means ‘stomach stone’ (in Greek, gastros = stomach, lithos = stone), and they thus refer to rocks that somehow made it into the digestive tract of an animal.” Wings, O. 2007. A review of gastrolith function with implications for fossil vertebr
ates and a revised classification. Acta Palaeontologica Polonica, 52: 1-16.
p. 197 “For one, they can be divided into two categories: bio-gastroliths and geo-gastroliths.” Wings (2007).
p. 197 “These bio-gastroliths are deposits of calcium oxalate, which form in people’s kidneys as a result of calcium imbalances… .” Coe, F.L., Evan, A., and Worcester, E. 2005. Kidney stone disease. Journal of Clinical Investigation, 115: 2598-2608.
p. 197 “Gallstones, on the other hand, are more organic than mineral and are normally composed of cholesterol, although these can sometimes have calcium mixed in as well.” Attili, A.F., de Santis, A., Capri, R., Repice, A.M., and Maselli, S. 1995. The natural history of gallstones: The GREPCO experience. Hepatology, 21: 656-660.
p. 198 “Remarkably, some crustaceans, such as marine crabs and freshwater crayfish, secrete their own bio-gastroliths of calcium carbonate.” Greenway, P. 1985. Calcium balance and moulting in the Crustacea. Biological Reviews, 60: 425-454.
p. 198 “In contrast, geo-gastroliths are rocks made outside of animals’ bodies by normal geological processes… .” Wings (2007).
p. 198 “However, the width of a gastrolith seemingly never exceeds 3% the length of the animal.” Wings (2007).
p. 199 “I have watched videos of crows doing the same thing, deliberately walking along and selecting pea-sized gravel to eat.” One such video, titled “Crow (Corvus brachyrhynchos) Swallowing Gravel in Vancouver BC 10Apr2010,” is here: http://www.youtube.com/ watch?v=Gg5gGXCVNr4
p. 200 “This process, also known as trituration, is like having a food processor in the upper part of an animal’s digestive system.” Wings (2007).
p. 200 “In birds that use gastroliths for just this function, their alimentary canal, from top to bottom, goes like this: mouth, esophagus… .” Proctor, N.S., and Lynch, P.J. 1998. Manual of Ornithology: Avian Structure and Function. Yale University Press, New Haven, Connecticut: 352 p.
p. 201 “One is in predatory birds, such as hawks, which may swallow a few pea-sized rocks, keep them in their digestive tracts for a while, and then regurgitate them before hunting.” Bruce, T. 2007. Observations of stone-eating in two species of neotropical falcons (Micrastur semitorquatus and Herpetotheres cachinnans). Journal of Raptor Research, 41: 74-76.
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