Theropods jump categories

The Dinosaurs Rediscovered, Michael Benton, Thames and Hudson.

When I was a child my favourite dinosaur book was a 1977 hardcover compendium entitled A Natural History of Dinosaurs. It wasn’t necessarily a kids’ book, but I had those as well. The book had colour plates with dinosaurs dragging their tails and looking very reptilian, certainly without any hint of a feather. Except, that is, for Archaeopteryx, which at the time was something of an anomaly, but was seen as a missing link between dinosaurs and birds, proof perhaps that a tiny thread had made it through the end-of-Cretaceous mass extinction.

There was no definitive conclusion as to why that mass extinction occurred. One kids’ book I had (a Golden Book, I think) simply concluded with the words ‘no-one knows why’, or similar. The authors of my 1977 history, being more thorough, discussed the suppositions, and, interestingly, suggested that climate change may have been to blame, with evidence of shifting continents (towards what we know of their configuration today) creating drier conditions and colder climates generally.

A lot has changed in dinosaur research since then, including the idea that dinosaurs held their tails upright as a counter-balance for the head. The much-publicised Chicxulub asteroid is generally agreed to have finished off the dinosaurs, though they might have already been in decline partly due to enormous volcanic activity in what is now India. And as for a select few scraping through as birds, this turned out to be more-or-less correct, because while many dinosaurs had feathers, a 2018 study suggested that only a few, small, ground-dwelling proto-birds were able to survive the post-asteroid apocalypse.

In The Dinosaurs Rediscovered Michael Benton covers the asteroid and notes that the Chicxulub explanation was resisted initially because palaeontologists were entrenched in thinking in models of slow change, as per, originally, Charles Lyell, and a catastrophic explanation seemed a too convenient, almost biblical theory. Benton also notes a brilliant example of how narrow research can enliven a discipline. One researcher found that the asteroid hit in June, such improbably specific date-fixing illuminated by the stage of growth lily flowers were at when they died and were fossilised.

The Dinosaurs Rediscovered also covers work done on origins, which is pushing back the date of creatures we can call dinosaurs, partly through research in the past decade on silesauridae, slender, dino-like relatives of dinosaurs. Even more recent are arguments that climate change may have accounted for the rise of the dinosaurs, which perhaps didn’t just outcompete their rivals. This is all a picture of life on earth as seasonal, times of proliferation and experiment truncated by mass die-offs. Or perhaps like the stock market. (Many ruminate on what this means for the survival of our own species.)

Computers help a lot more than they did in 1977, obviously, with explaining and mapping this multi-branched proliferation. But research doesn’t always clarify. Previously stable ideas in descent and species are being challenged, including a ‘bombshell’ rethink of the categories of bird and lizard hipped dinosaurs that many 8-year-olds are familiar with, whether now or in 1977. (Theropods – T-rex etc. – jump categories in this new theory.) Benton sticks to the old delineation but is generous enough to concede that the matter is nowhere-near settled. He seems delighted at both the refinement and the shaking-up. On other matters, he is less open, labelling ‘crackpots’ those who still suggest big dinosaurs lived mostly submerged in water. (He may be thinking here of Brian Ford, though Ford is not named in the book, who proposed that, amongst other things, T-rex lived its life like a crocodile.)

Otherwise, research on computer and in the field is producing hitherto unimagined detail, including how dinosaurs ate, how they got so big and how fast they ran (in T-rex’s case, not very fast, contrary to Jurassic Park). The authors of my 1977 book might be surprised by not only feathered dinosaurs, but also the knowledge of what colours the feathers were. The explosion in hunting and discovery of feathered dinosaurs in China shows that many dinosaurs had feathers, which were not initially for flight but later developed into flight feathers in smaller species of dinosaurs, and palaeontologists know colours from fossilised melanosomes, observable under microscopes in particularly well-preserved specimens. Sinosauropteryx, on Benton’s book’s cover, looked something like a chicken crossed with a fox, with a red and white stripy tail. Deinonychus, famed for its huge claw, now looks decidedly like a bird, rather than an ostrich naked of its feathers.

Poor old stegosaurs

The Rise and Fall of the Dinosaurs, Steve Brusatte, Macmillan

Too Big to Walk, Brian J. Ford, William Collins

While dinosaurs lie in the distant past, a couple of recent books, for those readers whose childhood fascination with dinosaurs extends into adulthood, are notable for showing that palaeontology is often entangled with personal quests and with personalities. Dinosaur history is inextricable from the more recent human history of discovery.

In the eighteenth century the fossils that were unearthed created puzzlement. What animals did these giant bones come from? When did they live? What did they mean for an understanding of Genesis and the Biblical Flood? It became clear that the animal kingdom was far richer than even what we see around us now.

In the 1970s and 80s, a major time for dinosaur discovery and prominence in the public imagination, dinosaurs, though intriguing, were still thought of as sluggish, dim-witted, lizard-like creatures that dragged their tails around and waded in swamps. And their disappearance remained a mystery. I remember a dinosaur book from my childhood ending with the words ‘nobody knows why’.

Now we do know why they died out, or at least we think we do. (Theories continue to change and be finessed.) An asteroid that hit the Mexican Yucatan Peninsula along with volcanic activity in India that split the Earth and poured out vast quantities of lava and toxic gases are thought to have ended the dinosaurs’ long reign.

Their lives have been revisited also. A lack of marks relating to tail dragging amongst footprints indicates dinosaurs held their tails aloft for balance and were more fleet-footed, which resulted, amongst other things, in the realignment of displayed dinosaur skeletons in museums. Birds, close relatives of dinosaurs, are smart, and most dinosaurs were thought to have been too, though the poor old stegosaurs continue to be labelled as dunces. The link to birds has been further strengthened by the discovery of traces of feathers in many dinosaurs, particularly in fossils from China, where an upsurge of fossil digs accompanies the rising economy.

Feathers do not automatically indicate flight, but were used for warmth and display, and palaeontologists are even beginning to picture what colours they might have been, due to the discovery of fossilised melanosomes, bearers of pigments whose various shapes correspond to various colours. Picturing dinosaur colour is something previously thought impossible.

Steve Brusatte is a palaeontologist with a particular interest in bird-like dinosaurs. His book is a brief history of the Mesozoic, the dinosaur era, neatly summarised by his title, The Rise and Fall of the Dinosaurs, and it relays the above developments in our understanding of dinosaur lives. But the book is as much about larger-than-life human figures, such as Edward Cope and Othniel Marsh, who fought the infamous nineteenth century ‘bone wars’ and who were not above sabotaging each other’s work, and Barnum Brown, who is famous for unearthing T. Rex. Also included are Brusatte’s contemporaries, including Paul Sereno, who worked on the same sites as Brown and who was once named in People magazine’s list of ‘most beautiful’.

Palaeontology continues to be populated by enthusiasts and eccentrics, who continue to dig up the bones of new species and fight over orthodoxies and heresies. If Brusatte represents the current orthodoxy, Brian Ford gives us the heresies in Too Big to Walk. Ford is a microbiologist who has provoked velociraptor-like ferocity from many palaeontologists for speculating that large dinosaurs at least were semi-aquatic.

Ford’s book is really two books in one. The first half is an entertaining history of the disciplines of geology and palaeontology. Whereas Brusatte orders his book by the chronology of the Mesozoic, Ford takes us through recent centuries, along the way digging up odd facts and burying popular fallacies. But he does this to set up his own place in the history of palaeontological theorising. His main purpose is to outline in the second half of the book his theory (and its reception) that dinosaurs were just too large to live on land, but like hippos and crocodiles spent most of their time in shallow lakes or seas.

The theory is an ingenious answer to a number of questions. Water could buoy up the giant necks and tails of sauropods. Predators such as T. Rex could move more freely, using their tails as rudders, whereas on land turning sideways quickly would be problematic. Life in water would stabilise body temperature, doing away with the need for dinosaurs to be warm-blooded. Ford also argues that the dates of the Yucatan asteroid and the dinosaurs’ decline don’t match, and that the loss of habitat, shallow lakes and seas, due to the breakup of the supercontinent Pangea, better explains the dinosaurs’ extinction.

He has been ridiculed for these outlandish ideas, often simply because he is not a palaeontologist. Like the climate change denying minority, he is accused of selective reading – ironically, as Ford is not one of them and admires pioneering climate change scientists.

For his part, Ford gets into the thick of online name-calling, and his sometimes unwieldy book unnecessarily contains correspondence with editors and detractors, as well as repeated sections of text and untailored papers, giving the impression of indiscriminate defensive firing. He dismisses opponent’s arguments on the basis of spelling mistakes, which would invalidate his own book. He compares himself to Galileo and thinks everyone is vindictive except himself.

As far as his theory goes, those detractors that bother to be respectful pile up contrary evidence. Perhaps there is middle ground. Perhaps some dinosaurs were more aquatic than others. What is more certain is that dinosaurs continue to stir passion in more than just five year olds. Ford’s theory is something of a response, indicated by his book’s title, to the fact that dinosaurs were somewhat unbelievable. Their intriguing other-worldly nature continues to inspire the search for new understanding through new evidence and new ideas.

(Originally reviewed for Journey magazine.)

Stromatolites to walking whales

donald-prothero

In the Adelaide Museum they have a lovely room dedicated to the Ediacara fossils – fossils from the Flinders Ranges that are some of the oldest multicellular fossils ever found. (The room features a former seabed rock slab suspended vertically in the middle of the room, allowing fossils on both sides of the slab to be viewed.) The finds resulted in the insertion of another period in the geological timescale (unsurprisingly, the Ediacaran Period).

This is just one of the major discoveries that feature in the short and snappy chapters of Donald Prothero’s The Story of Life in 25 Fossils, which covers significant fossils from stromatolites to the Burgess Shale to archaeopteryx to walking whales to ancient humans. He also weaves in the stories of the people that found them, including the amazing Mary Anning, famous for her discoveries of ichthyosaurs, plesiosaurs, pterosaurs and others in the nineteenth century at Lyme Regis in England, and who provided may specimens for the more famous male geologists of her time.

When I was a child, Australia seemed to have a dearth of interesting fossils, but it is interesting how significantly Australia features in both Prothero’s new book and our more recent understanding of the history of life – from still-living stromatolites at Shark Bay to the Flinders Ranges fossils, to walking whales from Jan Juc, to Adelaide Museum’s mesmerising opalised ichthyosaur and plesiosaur skeletons (surely some of the most beautiful freaks of geological history), and now, just this week, significant sauropod discoveries.