CHAPTER 2: DINOSAURS RISE UP
There are several reviews concerning the rise of dinosaurs during the Triassic. I wrote one with several of my colleagues, including Sterling Nesbitt and Randy Irmis of the Rat Pack: Brusatte et al., “The Origin and Early Radiation of Dinosaurs,” Earth-Science Reviews 101, no. 1–2 (July 2010): 68–100. Others have been written by Max Langer and various colleagues: Langer et al., Biological Reviews 85 (2010): 55–110; Michael J. Benton et al., Current Biology 24, no. 2 (Jan. 2014): R87–R95; Langer, Palaeontology 57, no. 3 (May 2014): 469–78; Irmis, Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 101, no. 3–4 (Sept. 2010): 397–426; and Kevin Padian, Earth and Environmental Science Transactions of the Royal Society of Edinburgh 103, no. 3–4 (Sept. 2012): 423–42.
Two excellent semitechnical books on the Triassic Period and how dinosaurs fit into the larger “assembly of modern ecosystems” have been written by my friend down the road at the National Museum of Scotland, Nick Fraser. In 2006 Nick published Dawn of the Dinosaurs: Life in the Triassic (Indiana University Press), and in 2010 he joined Hans-Dieter Sues in writing Triassic Life on Land: The Great Transition (Columbia University Press). These books are both richly illustrated (the former by the great paleoartist Doug Henderson) and contain references to most of the important primary literature on Triassic vertebrate evolution. The best maps of ancient Pangea—studiously drawn based on many lines of geological evidence that can trace ancient shorelines and determine the positions of land millions of years ago—have been produced by Ron Blakey and Christopher Scotese. Throughout the book, I have relied on these extensively when explaining the breakup of Pangea.
We have published a few papers on our excavations in Portugal, including a detailed description of the Metoposaurus skeletons found in the mass grave: Brusatte et al., Journal of Vertebrate Paleontology 35, no. 3, article no. e912988 (2015): 1–23; and a description of the phytosaur that lived with the “Super Salamanders”: Octávio Mateus et al., Journal of Vertebrate Paleontology 34, no. 4 (2014): 970–75. The German geology student who found the first Triassic specimens in the Algarve was Thomas Schröter, and the “obscure” paper that described the fossils he found was written by Florian Witzmann and Thomas Gassner, Alcheringa 32, no. 1 (Mar. 2008): 37–51.
The Rat Pack—Randy Irmis, Sterling Nesbitt, Nate Smith, Alan Turner, and their colleagues—have published numerous papers on the specimens they found at Ghost Ranch, the paleoenvironment of the area, and how their finds fit into the global context of Triassic dinosaur evolution. Among the most important are Nesbitt, Irmis, and William G. Parker, Journal of Systematic Palaeontology 5, no. 2 (May 2007): 209–43; Irmis et al., Science 317, no. 5836 (July 20, 2007): 358–61; and Jessica H. Whiteside et al., Proceedings of the National Academy of Sciences USA 112, no. 26 (June 30, 2015): 7909–13. Edwin Colbert comprehensively described the Ghost Ranch Coelophysis skeletons in his 1989 monograph The Triassic Dinosaur Coelophysis, Museum of Northern Arizona Bulletin 57: 1–160, and he recounted the story of their discovery in many of his gripping popular books on dinosaurs. Martín Ezcurra’s paper on Eucoelophysis was published in Geodiversitas 28, no. 4: 649–84. Sterling Nesbitt described Effigia in a short paper in 2006 in Proceedings of the Royal Society of London, Series B, vol. 273 (2006): 1045–48, and later as a monograph in the Bulletin of the American Museum of Natural History 302 (2007): 1–84.
My work on the morphological disparity of Triassic dinosaurs and pseudosuchians was published in two papers in 2008: Brusatte et al., “Superiority, Competition, and Opportunism in the Evolutionary Radiation of Dinosaurs,” Science 321, no. 5895 (Sept. 12, 2008): 1485–88; and Brusatte et al., “The First 50 Myr of Dinosaur Evolution,” Biology Letters 4: 733–36. These papers were cowritten with Mike Benton, Marcello Ruta, and Graeme Lloyd, my MSc supervisors at the University of Bristol and some of my most trusted colleagues in the field today. The publications that inspired me, written by Bakker and Charig, are cited and discussed in those papers. Many invertebrate paleontologists helped develop the standard morphological disparity methods, especially Mike Foote (who was on the faculty of my undergraduate institution, the University of Chicago, but whom I was unfortunately never able to take a course with) and Matt Wills, and I have also cited their papers extensively in my work.
The name Mike Benton pops up a lot in this section. I’ve said less about Mike in the main text than my other two academic advisors, Paul Sereno and Mark Norell, probably because I was in Bristol for too short of time to accumulate the sort of juicy stories that fit into the way I’ve chosen to write this narrative. But that is no reflection of Mike. He is a scientific superstar whose studies of vertebrate evolution and popular textbooks (particularly Vertebrate Palaeontology, which has gone through several editions with Wiley-Blackwell, most recently in 2014) have set the pulse for the entire field of vertebrate paleontology for decades. But despite the wide regard in which he is held, he is a humble man who is well loved for being a helpful supervisor to dozens of graduate students.
CHAPTER 3: DINOSAURS BECOME DOMINANT
The books Dawn of the Dinosaurs: Life in the Triassic and Triassic Life on Land: The Great Transition, both cited above, in the notes to chapter 2, provide excellent overviews of the end-Triassic extinction. Some of the topics of this chapter are also discussed in the review papers on early dinosaur evolution used as sources for chapter 2.
The lava erupting at the end of the Triassic created a huge amount of basaltic rock (including the Palisades of New Jersey), which covers part of four continents today. This is referred to as the Central Atlantic Magmatic Province (or CAMP), and has been well described by Marzoli and colleagues in Science 284, no. 5414 (Apr. 23, 1999): 616–18. The timing of the CAMP eruptions has been studied by Blackburn and colleagues, including Paul Olsen, in Science 340, no. 6135 (May 24, 2013): 941–45, and it is their work that shows that the eruptions took place in four large pulses over six hundred thousand years. Work by Jessica Whiteside, our friend from Portugal and Ghost Ranch, has shown that the extinctions on land and in the sea happened at the same time at the end of the Triassic, and that the first hints of extinction are synchronous with the first lava flows in Morocco. See Proceedings of the National Academy of Sciences USA 107, no. 15 (Apr. 13, 2010): 6721–25. Paul Olsen was also part of this research, as he was Whiteside’s PhD supervisor at Columbia University.
Changes across the Triassic-Jurassic boundary in atmospheric carbon dioxide, global temperature, and plant communities have been studied by, among others, Jennifer McElwain and colleagues in Science 285, no. 5432 (Aug. 27, 1999): 1386–90, and Paleobiology 33, no. 4 (Dec. 2007): 547–73; Claire M. Belcher et al., Nature Geoscience 3 (2010): 426–29; Margret Steinthorsdottir et al., Palaeogeography, Palaeoclimatology, Palaeoecology 308 (2011): 418–32; Micha Ruhl and colleagues, Science 333, no. 6041 (July 22, 2011): 430–34; and Nina R. Bonis and Wolfram M. Kürschner, Paleobiology 38, no. 2 (Mar. 2012): 240–64.
Paul Olsen has been publishing on the rift basins and fossils of eastern North America since just a few years after his teenage hijinks. He has written two technical overviews of the Pangean rift basin system (which geologists call the Newark Supergroup), both with Peter LeTourneau, The Great Rift Valleys of Pangea in Eastern North America, vols. 1–2 (Columbia University Press, 2003), and a very useful review paper on the subject in the Annual Review of Earth and Planetary Sciences 25 (May 1997): 337–401. In 2002 Olsen published an important paper summarizing his years of work on footprints, which presented evidence for the rapid radiation of dinosaurs after the end-Triassic extinction: Science 296, no. 5571 (May 17, 2002): 1305–7.
There is a huge literature on sauropod dinosaurs. One of the best technical books on these iconic dinosaurs was edited by Kristina Curry Rogers and Jeff Wilson: The Sauropods: Evolution and Paleobiology (University of California Press, 2005). A good technical summary was written by Paul Upchurch, Paul Barrett, and Peter Dodson for the second edition of the classic sc
holarly dinosaur encyclopedia, The Dinosauria (University of California Press, 2004), and I wrote a less technical review of the group in my 2012 textbook, Dinosaur Paleobiology (Hoboken, NJ: Wiley-Blackwell). My early-career colleagues Phil Mannion and Mike D’Emic have recently been doing a lot of excellent descriptive work on sauropods, along with their advisors Upchurch, Barrett, and Wilson.
We described our sauropod dinosaur trackways from Skye in 2016: Brusatte et al., Scottish Journal of Geology 52: 1–9. Some of the earlier fragmentary records of Scottish sauropods were presented by my Glasgow buddy Neil Clark and Dugie Ross in the Scottish Journal of Geology 31 (1995): 171–76; by my incomparable Scottish nationalist comrade Jeff Liston, Scottish Journal of Geology 40, no. 2 (2004): 119–22; and by Paul Barrett, Earth and Environmental Science Transactions of the Royal Society of Edinburgh 97: 25–29.
Calculating the body weights of dinosaurs has been the focus of numerous studies. A pioneering work by J. F. Anderson and colleagues was the first to recognize the relationship between long-bone thickness (technically, circumference) and body weight (technically, mass) in modern and extinct animals: Journal of Zoology 207, no. 1 (Sept. 1985): 53–61. More recent work by Nic Campione, David Evans, and colleagues has refined this approach: BMC Biology 10 (2012): 60; and Methods in Ecology and Evolution 5 (2014): 913–23. These methods have been used to estimate the masses of nearly all dinosaurs by Roger Benson and coauthors: PLoS Biology 12, no. 5 (May 2014): e1001853.
The photogrammetry-based method for estimating mass was pioneered by Karl Bates and his PhD supervisors Bill Sellers and Phil Manning in PLoS ONE 4, no. 2 (Feb. 2009): e4532, and has since been expanded on in several publications, including Sellers et al., Biology Letters 8 (2012): 842–45; Brassey et al., Biology Letters 11 (2014): 20140984; and Bates et al., Biology Letters 11 (2015): 20150215). Peter Falkingham has published a primer on how to collect photogrammetric data in Palaeontologica Electronica 15 (2012): 15.1.1T. The work on sauropods that I took part in, led by Karl, Peter, and Viv Allen, was published in Royal Society Open Science 3 (2016): 150636.
It is worth noting that both of these methods—equations based on long-bone circumference and photogrammetric models—do have sources of error. These errors become larger for larger dinosaurs, particularly as the methods cannot be validated in modern animals that are anywhere near the size of sauropods. The original publications cited above extensively discuss these sources of error and, in many cases, present a range of plausible body masses for each dinosaur species based on this understanding of uncertainty.
The biology and evolution of sauropods are subjects of a fascinating collection of research papers gathered together into the book Biology of the Sauropod Dinosaurs: Understanding the Life of Giants, ed. Nicole Klein and Kristian Remes (Indiana University Press, 2011). A chapter in this book, written by Oliver Rauhut and colleagues, discusses in detail the evolution of the sauropod body plan: how all the characteristic features of the group came together over millions of years. The question of why sauropods were able to get so big was recently tackled in an excellent, accessible review paper on sauropod biology written by Martin Sander and a team of researchers who studied this mystery over many years, funded by a large German research grant: Biological Reviews 86 (2011): 117–55.
CHAPTER 4: DINOSAURS AND DRIFTING CONTINENTS
For information on Zallinger’s mural, check out Richard Conniff’s House of Lost Worlds: Dinosaurs, Dynasties, and the Story of Life on Earth (Yale University Press, 2016) or Rosemary Volpe’s The Age of Reptiles: The Art and Science of Rudolph Zallinger’s Great Dinosaur Mural at Yale (Yale Peabody Museum, 2010). Better yet, go see the mural for yourself at the Peabody Museum if you have the chance. It’s a stunning work of art.
There are many popular accounts of the Cope-Marsh Bone Wars, but for a scholarly and matter-of-fact version, I recommend John Foster’s excellent book Jurassic West: The Dinosaurs of the Morrison Formation and Their World (Indiana University Press, 2007). Foster has spent decades excavating dinosaurs throughout the American West, and his book is a masterful summary of the Morrison dinosaurs, the world they lived in, and the history of their discovery. I relied on this book as my primary source for the historical information in this chapter. The book cites numerous primary sources, including the many research papers that Cope and Marsh published during their hyperactive feud.
The story of Big Al is based on a report by then University of Wyoming and now BLM paleontologist Brent Breithaupt, written for the National Park Service and published as “The Case of ‘Big Al’ the Allosaurus: A Study in Paleodetective Partnerships,” in V. L. Santucci and L. McClelland, eds., Proceedings of the 6th Fossil Resource Conference (National Park Service, 2001), 95–106.
Interesting studies have been published on the body size (Bates et al., Palaeontologica Electronica, 2009, 12: 3.14A) and pathologies (Hanna, Journal of Vertebrate Paleontology, 2002, 22: 76–90) of Big Al, and the computer modeling study of Allosaurus feeding that I refer to was published by Emily Rayfield and colleagues (Nature, 2001, 409: 1033–37). Information about Kirby Siber was gleaned from a profile in Rocks & Minerals Magazine, written by John S. White (2015, 90: 56–61). For a balanced take on the subject of commercial fossil collecting and the selling of dinosaur fossils, Heather Pringle’s article in Science (2014, 343: 364–67) is a good place to start.
There are many great research articles on the sauropods of the Morrison Formation. The best place to start is with the sauropod chapter in the academic textbook The Dinosauria, written by sauropod experts Paul Upchurch, Paul Barrett, and Peter Dodson (University of California Press, 2004). Over the past two decades, there has been considerable debate about how different sauropods held their necks, which I summarize in my textbook Dinosaur Paleobiology, with citations to the relevant literature, much of which has been written by Kent Stevens and Michael Parrish. There has also been a great deal of work on sauropod feeding habits, with some of the more important papers by Upchurch and Barrett. These are discussed and summarized in both my textbook and the 2011 Sander et al. paper on sauropods cited at the end of the notes for chapter 3 above. More recently, Upchurch, Barrett, Emily Rayfield, and their PhD students David Button and Mark Young have done groundbreaking computer modeling work aimed at understanding how different sauropods fed (Young et al., Naturwissenschaften, 2012, 99: 637–43; Button et al., Proceedings of the Royal Society of London, Series B, 2014, 281: 20142144).
The chapters in The Dinosauria are good sources of information on the Late Jurassic dinosaurs of other continents. The now famous Late Jurassic dinosaurs of Portugal have been studied extensively by Octávio Mateus, my friend and co-excavator of the “SuperSalamander” bone bed whom we met earlier. For a review, see Antunes and Mateus, Comptes Rendus Palevol 2 (2003): 77–95. The Late Jurassic dinosaurs of Tanzania were excavated during a series of remarkable German-led expeditions in the early 1900s, which are described in the detailed historical account of Gerhard Maier in his book African Dinosaurs Unearthed: The Tendaguru Expeditions (Indiana University Press, 2003).
My primary source for the changes that occurred across the Jurassic-Cretaceous boundary is an excellent review paper by Jonathan Tennant and coauthors (Biological Reviews, 2016, 92 (2017): 776-814). I was one of the peer reviewers of this paper, and of the many hundreds of manuscripts I’ve reviewed, this one may be the one that I learned the most from. Jon did this work as a PhD student in London. Those Internet geeks among you may recognize him as a prolific tweeter and a very passionate communicator of science through blogs and social media.
There have been many profiles of Paul Sereno in books, magazines, and newspapers. Some of those I wrote back in the late 1990s and early 2000s during my fanboy days, but I won’t give the specifics here just to make it a little extra difficult for anyone who wants to track down those embarrassing excuses for journalism. One day Paul will probably (I hope!) write his own story, but in the meantime, there is extensive information on his expeditions and discover
ies on his lab website (paulsereno.org). Some of his more important African discoveries include the following, with short citations to the relevant scientific papers in parentheses: Afrovenator (Science, 1994, 266: 267–70); Carcharodontosaurus saharicus and Deltadromeus (Science, 1996, 272: 986– 91); Suchomimus (Science, 1998, 282: 1298–1302); Jobaria and Nigersaurus (Science, 1999, 286: 1342–47); Sarcosuchus (Science, 2001, 294: 1516–19); Rugops (Proceedings of the Royal Society of London Series B, 2004, 271: 1325–30). Paul and I described Carcharodontosaurus iguidensis together in 2007 (Brusatte and Sereno, Journal of Vertebrate Paleontology 27: 902–16) and Eocarcharia a year later (Sereno and Brusatte, Acta Palaeontologica Polonica, 2008, 53: 15–46).
There is a huge literature of textbooks and how-to guides on the subject of building family trees (phylogenies) using cladistics. The theory behind the methods was developed by the German entomologist Willi Hennig, who outlined his ideas in a paper (Annual Review of Entomology, 1965, 10: 97–116) and a landmark book, Phylogenetic Systematics (University of Illinois Press, 1966). Those works can be quite dense, but more approachable are textbooks by Ian Kitching et al. (Cladistics: The Theory and Practice of Parsimony Analysis, Systematics Association, London, 1998), Joseph Felsenstein (Inferring Phylogenies, Sinauer Associates, 2003), and Randall Schuh and Andrew Brower (Biological Systematics: Principles and Applications, Cornell University Press, 2009). I also give a general explanation, using dinosaurs as an example, in the phylogeny chapter of my textbook Dinosaur Paleobiology.
The Rise and Fall of the Dinosaurs Page 28