The Desert Bones The Paleontology and Paleoecology of Mid-Cretaceous North Africa

The Desert Bones offers a meticulous and exhaustive overview of the often fragmentary material found throughout this region. It brings to life North Africa as it was during the Cenomanian Age, 100.5–93.9 million years ago: a time of wetlands, rudist reefs and, of course, spinosaurs.

Having just read The Lost Dinosaurs of Egypt, Ijouiher coincidentally mentions it as a very important influence; reading it was "the closest I've ever come to a religious conversion" (p. xi). The other book he credits, which I reviewed back in 2021, is Jurassic West. Indeed, The Desert Bones is part of the same series, Life of the Past, and Ijouiher explicitly mentions wanting to do for North Africa what Foster did for the USA: provide an as-complete-as-possible overview of a major fossil locality.

To set the stage, Ijouiher opens with a chapter on the palaeoenvironment and stratigraphy. This discusses the different rock strata and their naming conventions, with stratigraphical charts clarifying the sometimes confusing tangle of revisions and different local naming schemes for strata of the same age. What was missing in comparison with Jurassic West were photos of the different localities and the different rock types encountered there. Regardless, we have a clear picture of what North Africa was like at this time: "effectively a giant version of the modern Nile and Okavango deltas" (p. 9)—an otherwise arid inland region was fringed by forested coastal wetlands. With sea levels higher than today, a noteworthy feature was the Trans-Saharan Seaway that connected the Tethys Sea with the South Atlantic, bisecting the land into a western and an eastern half.

The bulk of the book, taking up 180 of the 257 pages, is a systematic catalogue of the flora and especially fauna, covering invertebrates, fish, and other tetrapods. These chapters are richly illustrated with colour photos of fossils and numerous colour reconstructions by Joschua Knüppe and Andrey Atuchin. For some plant and invertebrate groups, we have so much data that Ijouiher has wisely decided to tabulate named taxa in the appendix rather than describe each in detail. For vertebrate taxa, however, his descriptions are more exhaustive, even discussing individual unnamed fragments. Given my review of Spinosaur Tales, I was particularly interested in the 6-page treatment of Spinosaurus. Ijouiher is largely on the same page in his views, and it is odd that Hone & Witton did not reference this book.

I appreciated that Ijouiher tries, as much as is possible when making such a systematic list, to liven up the narrative. He provides research history where species have been studied long enough and inserts his own carefully caveated opinion where he agrees or disagrees with others. Another welcome aspect of his writing is that he is (mostly) careful to introduce scientific conventions and terminology that lay readers might not be familiar with. However, once he gets to his stomping grounds of vertebrate taxonomy and phylogenetics, he falters somewhat in this tendency.

Chapter 6, then, is where Ijouiher can take a step back and ask what this exercise in cataloguing and enumerating reveals about the region's ecology. He describes it as a palaeoecologist's dream in that you can reconstruct an entire ecosystem. Rather than coral reefs, reefs were a flatter landscape consisting of rows of oysters and rudists (an extinct group of bivalves). On land, he considers the flora, looking at primary production, population dynamics, and the import, export, and recycling of nutrients. The coastlines were densely overgrown by the tree fern Weichselia that functionally behaved like mangroves do today, growing directly out of the shallow ocean floor and trapping sediment. Few animals lived here permanently, but many commuted daily or visited seasonally. Ijouiher agrees with those who argue that snails, rather than insects and crabs, had a dominant role in nutrient recycling. Turning to the vertebrates, he favours the idea that the eastern and western halves of North Africa formed a continuous ecological province, despite a seaway bisecting them. Next, he takes a stab at discussing abundance data, Stromer's Riddle (i.e. the perceived overabundance of predators and what these were eating), predator-prey ratios, and what, if any, evidence there is for niche partitioning. Interestingly, the general conclusion is that this was a productive ecosystem thanks to plankton. Their short generation times fed a rich diversity of fish that could directly sustain carnivores, even if herbivores were on the menu.

There is a caveat to the ecology chapter, though. At 30 pages, it is quite short, and most of it concerns comparisons between Morocco's Kem Kem Formation and Egypt's Bahariya Formation. Ijouiher cannot avoid writing a circumspect chapter in which he has to remain frustratingly generic. After trawling through the preceding four chapters, it is easy to see why. First, much of the material recovered from North Africa is fragmentary. Second, crucial material remains undescribed, and some has been lost. Third, the region is mostly poorly explored, except for the abovementioned two locations.

To be crystal clear, this is in no way intended as a slight towards Ijouiher as it certainly is not for want of trying. What it indicates is the state of play: the reason this book cannot quite deliver the way Jurassic West did is that North Africa is not the well-researched Morrison Formation. In some ways, what Ijouiher has single-handedly pulled off here is harder: a meticulous compilation and interpretation in the teeth of the fragmentary nature of the data. Examining the 42-page reference section reveals the scope of his source material: not just scientific papers and books, but also Master's and PhD theses, conference proceedings, meeting abstracts, geological survey reports, informative blog posts by professional palaeontologists, personal communications, publications dating back to the mid-1800s, and a substantial body of French, German, and Italian literature. I came away with the impression that few, if any, rocks were left unturned.

Who, then, is this book for? Given this was published three years ago, science has advanced, and some topics will be (somewhat) outdated. If you are in this field, you will already know this, but you are also not the primary audience. Instead, this book is for the serious enthusiast: as with comparable volumes in the Life of the Past series, they are quite technical and not light-hearted popular science you devour in an afternoon. Another group well-served would be professionals coming from a different field who need a thoroughly researched entry point into the literature.