Dinosaurs Without Bones (58 page)

p. 87
   “Paleontologists who studied these fossils agree that both dinosaurs must have been buried instantaneously… .” So much has been
written about these dinosaurs and how they were buried, I won’t even try to pick any one. But probably the best general explanation for how collapsing dunes (and wet sand) could have been responsible for the exquisite preservation of the Late Cretaceous Mongolian dinosaurs is: Dingus, L., and Loope, D. 2000. Death in the dunes. Natural History, 109: 50-57.

p. 90
   “Nonetheless, eggs and eggshells are actually body fossils.” Martin, A.J. 2006. Introduction to the Study of Dinosaurs (2nd Edition). Wiley-Blackwell, Oxford, U.K.: 560 p.

p. 91
   “Vertebrates that lay eggs today, such as reptiles, birds, and monotremes (egg-laying mammals, such as the platypus and echidnas), are all classified as amniotes.” Benton, M.J. 2005. Vertebrate Palaeontology (3rd Edition). Wiley-Blackwell, Oxford, U.K.: 455 p.

p. 91
   “We currently have no reasonable evidence that dinosaurs gave birth to live young, but this trait (viviparity) showed up in ichthyosaurs… .” Many articles have been published on individual ichthyosaurs and their giving live birth. But for an exploration of how it evolved in Mesozoic marine reptiles, as well as an overview of the evidence for biological development in fossils, read: Sánchez, M.R. 2012. Embryos in Deep Time: The Rock Record of Biological Development. University of California Press, Berkeley, California: 265 p.

p. 91
   “Although that strategy has worked very well for sea turtles for the past 100 million years… .” A fossil sea-turtle nest—from the Cretaceous Period, no less—was just recently described in detail, with its traits compared to those of modern sea turtles: Bishop, G.A., Pirkle, F.L., Meyer, B.K., and Pirkle, W.A. 2011. The foundation for sea turtle geoarchaeology and zooarchaeology: morphology of recent and ancient sea turtle nests, St. Catherines Island, Georgia, and Cretaceous Fox Hills Sandstone, Elbert County, Colorado. In Bishop, G.A, Rollin, H.B., and Thomas, D.H. (editors), Geoarchaeology of St. Catherines Island, Georgia. Anthropological Papers of the American Museum of Natural History, No. 94: 247-269.

p. 91
   “Viviparity also occurs in some modern species of lizards and snakes, including sea snakes… .” Andrews, R.M., and Mathies, T. 2000. Natural history of reptilian development: constraints on the evolution of viviparity. BioScience, 50: 227-238.

p. 92
   “The oldest known dinosaur eggs come from Early Jurassic rocks… .” Reisz, R.R., Evans, D.C., Roberts, E.M., Dieter-Sues, H., and Yates, A.M. 2012. Oldest known dinosaurian nesting site and reproductive biology of the Early Jurassic sauropodomorph Massospondylus. Proceedings of the National Academy of Science, 109: 2428-2433.

p. 92
   “These categories, based on shell microstructure, arrangements of the pores, and overall forms, were given linguistically daunting
names such as Spheroolithidae, Ovaloolithidae….” Zelenitsky, D. K., Horner, J.R., and Therrien, F. 2012. Dinosaur eggs. In Brett-Surman, M.K., Holtz, T.R., Jr., and Farlow, J.O. (editors), The Complete Dinosaur (2nd Edition). Indiana University Press, Bloomington, Indiana: 613-620.

p. 93
   “Paleontologists who studied Troodon egg clutches were surprised to notice that not only were eggs paired but also aligned vertically.” Varricchio et al. (1997).

p. 93
   “Thus far, we only know of one instance in which an egg assemblage contained embryonic bones of more than one species of dinosaur… .” This find was first described in 1994, then updated in 2009. (1) Norell, M.A., Clark, J.M., Dashzeveg, D., Barsbold, R., Chiappe, L.M., Davidson, A.R., McKenna, M.C., Perle, A., and Novacek, M.J. 1994. A theropod dinosaur embryo and the affinities of the Flaming Cliffs dinosaur eggs. Science, 266: 779-782. (2) Bever, G.S., and Norell, M.A. 2009. The perinate skull of Byronosaurus (Troodontidae) with observations on the cranial ontogeny of paravian theropods. American Museum Novitates, 3657: 51 p.

p. 94
   “Sea turtles, for example, have a temporary extension of their beaks when born, which is applied like a can opener from the inside of the egg to open it.” Ruckdeschel, C., and Shoop, C.R. 2006. Sea Turtles of the Atlantic and Gulf Coasts of the United States. University of Georgia Press, Athens, Georgia: 152 p.

p. 94
   “Similar parts have been described from Late Cretaceous sauropod embryos in Argentina… .” Garcia, R.A. 2007. An “egg-tooth”-like structure in titanosaurian sauropod embryos. Journal of Vertebrate Paleontology, 27: 247-252.

p. 94
   “Have hatchling trace fossils been identified in dinosaur eggs?” Mueller-Töwe, I. J., Sander, P.M., Schüller, H., and Thies, D. 2002. Hatching and infilling of dinosaur eggs as revealed by computed tomography. Palaeontographica Abteilung A, 267: 119-168.

p. 95
   “Yet these trace fossils have not been discovered yet either, despite many decades of our demonizing mammals for eating too many dinosaur eggs… .” No one is quite sure when the “Mammals ate dinosaur eggs, so dinosaurs went extinct” idea originated, but it is a persistent myth. And myth it is, because dinosaurs and mammals lived together in the Mesozoic for about 150 million years, yet we still have no evidence—trace fossil or otherwise—for mammals eating dinosaur eggs, let alone eating enough of them to hasten dinosaur extinction.

p. 96
   “Unidentified therizinosaurs from the Late Cretaceous of Mongolia, which may have even formed nesting colonies.” This fantastic discovery of a probable therizinosaur nesting colony
was announced in a talk at the Society of Vertebrate Paleontology meeting in October 2013: Kobayashi, Y., Lee, Y.-N., Barsbold, R., Zelenitsky, D., and Tanaka, K. 2013. First record of a dinosaur nesting colony from Mongolia reveals nesting behavior of therizinosauroids. Journal of Vertebrate Paleontology, Program and Abstracts, 2013: 155.

p. 96
   “The ceratopsians Psittacosaurus from the Early Cretaceous in China, and Protoceratops from the Late Cretaceous in Mongolia… .” (1) Meng, Q., Liu, J., Varricchio, D.J., Huang, T., and Gao, C. 2004. Parental care in an ornithischian dinosaur. Nature, 431: 145-146. (2) Fastovsky, D., Weishampel, D., Watabe, M., Barsbold, R., Tsogtbaatar, K., and Narmandakh, P. 2011. A nest of Protoceratops andrewsi (Dinosauria, Ornithischia). Journal of Paleontology, 85 (6): 1035-1041. p. 96       “… a nearly complete specimen of Citipati osmolskae—missing only its head—was found in a sitting position above a clutch of long oval eggs.” (1) Norell, M.A., Clark, J.M., Chiappe, L.M., and Dashzeveg, D. 1995. A nesting dinosaur. Nature, 378: 774-776. (2) Clark, J.M., Norell, M.A., and Chiappe, L.M. 1999. An oviraptorid skeleton from the Late Cretaceous of Ukhaa Tolgod, Mongolia, preserved in an avian-like brooding position over an oviraptorid nest. American Museum Novitates, 3265: 1-36.

p. 97
   “Indeed, the discovery of a dinosaur egg—containing embryonic bones, no less—in Late Cretaceous shallow-marine deposits in Alabama… .” Lamb, J.P., Jr. 2001. Dinosaur egg with embryo from the Cretaceous (Campanian) Mooreville Chalk Formation, Alabama. Journal of Vertebrate Paleontology, 21 (Supplement to 3): 70A.

p. 97
   “If talking just about reptile nests, these can be summarized into two broad categories: ground nests and hole nests, with ground nests made on the ground surface and hole nests below the surface.” Martin (2006). p. 98             “Bird nests range from simple scrapes in the ground, to better defined excavations… .” Elbroch, M., and Marks, E. 2001. Bird Tracks and Sign of North America. Stackpole Books, Mechanicsburg, Pennsylvania: 456 p.

p. 98
   “For instance, one good candidate for underground nesting would have been the small Cretaceous ornithopod Oryctodromeus cubicularis… .” Varricchio et al. (2007). p. 98 “For arboreal nests, a few small feathered tree-climbing, gliding, and flying non-avian dinosaurs are known from Early Cretaceous rocks of China.” (1) Czerkas, S.A., and Yuan, C. 2002. An arboreal maniraptoran from northeast China. In Czerkas, S.J. (editor), Feathered Dinosaurs and the Origin of Flight. The Dinosaur Museum Journal 1. The Dinosaur Museum, Blanding, Utah: 63-95. (2) Zhang, F., Zhou, Z., Xu, X., Wang, X., and Sullivan, C. 2008. A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers. Nature, 455: 1105-1108.

p. 99
“Fortunately, paleontologists who have interpreted the few indisputable dinosaur nests in the geologic record made a nice little checklist for the rest of us to follow… .” Chiappe
et al
. (2004).

p. 100
“At the time of this discovery, more than a hundred years had elapsed between paleontologists first linking fossil eggs to dinosaurs, which was in 1869.” Matheron, M. 1869. Notice sur les Reptiles fossils des depots fluvio-lacustres Crétacés du basin a lignote de Fuveau. Memo
ires l’Academie Impériale des Sciences, Belles-Lettres et Arts de Marseille: 34
5-379.

p. 100
“… John (‘Jack’) Horner and his friend Robert (‘Bob’) Makela … found depressions filled with eggs and partly grown juveniles of the large ornithopod dinosaur Maia
saura peeblesorum.” (
1) Horner, J.R., and Makela, R. 1979. Nest of juveniles provides evidence of family structure among dinosaurs. Natu
re, 28
2: 296-298. (2) Horner, J.R. 1982. Evidence of colonial nesting and ‘site fidelity’ among ornithischian dinosaurs. Natu
re, 29
7: 675-676. (3) Horner, J.R. 1984. The nesting behavior of dinosaurs. Scie
ntific American, 25
0: 130-137.

p. 101
“Recognized by David (‘Dave’) Varricchio, who was a Ph.D. student of Horner’s in the early 1990s, these structures were the first dinosaur nests defined solely as trace fossils.” (1) Varricchio et a
l. (199
7, 1999).

p. 102
“Eggs in the clutch were oriented almost vertically, narrow ends down but also pointing toward the center.” Varricchio et a
l. (199
7).

p. 104
“The width of the nest, rim included, was about half the total body length of an adult Troo
don…
.” Varricchio et a
l. (199
9).

p. 104
“Just to compare, though, crocodilians and sea turtles normally take just a few hours to dig a hole nest.” (1) Kusklan, J.A., and Mazzotti, F.J. 1989. Population biology of the American crocodile. Jour
nal of Herpetology, 23
: 7-21. (2) Ruckdeschel and Shoop (2006).

p. 105
“Some of these mounds, such as nests of the Australian brush turkey (Alec
tura lathami), c
an be 2 m (6.6 ft) tall and 20 m (67 ft) wide.” (1) Jones, D.N. 1988. Construction and maintenance of the incubation mounds of the Australian brush-turkey Alec
tura lathami. Em
u,
88
: 210-218. (2) Seymour, R.S., and Bradford, D.F. 1992. Temperature regulation in the incubation mounds of the Australian brush-turkey. The
Condor, 94
: 134-150.

p. 105
“These anatomical traits of Troo
don moth
ers are interpreted on the basis of how eggs are paired.” Varricchio et a
l. (199
7, 1999).

p. 106
“Even better evidence of brooding behavior is the adult itself… .” Varricchio et a
l. (199
7, 1999).
D.J., Moore, J.R., Erickson, G.M., Norell, M.A., Jackson, F.D., and Borkowski, J.J. 2008. Avian parental care had dinosaur origin.
Science
, 322: 1826-1828. (2) Schweitzer, M.H., Wittmeyer, J.L., and Horner, J.R. 2005. Gender-specific reproductive tissue in ratites and
Tyrannosaurus rex. Science
, 308: 1456-1460.

p. 106
“Not coincidentally, this same sort of paternal protection is a modern behavior likewise seen in nesting emus, ostriches, and rheas.” Varricchio, D.J. 2011. A distinct dinosaur life history?
Historical Biology
, 23: 91-107.

p. 107
“Much study on the sedimentary rocks there, including their geochemistry, revealed that this part of Montana was probably warm and semi-arid 75 to 80 million years ago.” Rogers, R.R. 1990. Taphonomy of three dinosaur bone beds in the Upper Cretaceous Two Medicine Formation of northwestern Montana: evidence for drought-related mortality.
Palaios
, 5: 394-413.

p. 107
“Forests were farther away from the nesting grounds, as was an active volcano that occasionally erupted and helped to preserve both the trees of these forests and dinosaur bones.” Roberts, E.M., and Hendrix, M.S. 2000. Taphonomy of a petrified forest in the Two Medicine Formation (Campanian), northwest Montana: implications for palinspastic restoration of the Boulder Batholith and Elkhorn Mountains volcanics.
Palaios
, 15: 476-482.

p. 108
“This is a behavioral trait shared with nesting sea turtles, crocodilians, and birds, in which mothers come back repeatedly to the same nesting site… .” (1) Ruckdeschel and Shoop (2006). (2) Thorbjarnarson, J.B., and HernaÅLndez, G. 1993. Reproductive ecology of the Orinoco crocodile (
Crocodylus intermedius
) in Venezuela. I. Nesting ecology and egg and clutch relationships.
Journal of Herpetology
, 27: 363-370. (3) Hepp, G.R., and Kennamer, R.A. 1992. Characteristics and consequences of nest-site fidelity in wood ducks.
The Auk
, 109: 812-818.

p. 108
“… I later did a study with Varricchio on fossil insect nests near the
Troodon
nesting sites.” Martin, A.J., and Varricchio, D.J. 2011. Paleoecological utility of insect trace fossils in dinosaur nesting sites of the Two Medicine Formation (Campanian), Choteau, Montana.
Historical Biology
, 23: 15-25.

p. 109
“Horner originally conjectured that these cocoons, which were also near the
Maiasaura
nest sites, were those of carrion beetles, which he imagined fed on hatched eggs, or dead eggs and hatchlings.” Horner, J.R., and Gorman, J. 1988.
Digging Dinosaurs: The Search that Unraveled the Mystery of Baby Dinosaurs.
Workman Publishing Company, New York: 210 p.

p. 109
“Thus it was not surprising that one of the same people who studied
the
Troodon
nests and eggs with Varricchio in Montana, Frankie Jackson, later noticed and defined similar structures… .” Chiappe
et al.
(2004).