Fossil Lake in Fossil, Wyoming is a world famous palaeontological locality that has yielded thousands of spectacular, often beautiful fossils. And commemorating this record is a spectacular, often beautiful, book. The Lost World of Fossil Lake is a masterful, heavily illustrated 2013 volume – written by palaeontologist Lance Grande, and featuring photos taken by Grande and John Weinstein – that chronicles the many fossil organisms found at Fossil Lake, and does so in amazing, compelling fashion. This thick, weighty book serves both as a visual tour of one of the world’s most fantastic fossil-bearing sites, and as a semi-technical treatise that reviews an impressively complete, complex Paleogene assemblage.

The rocks at Fossil Lake belong to the Fossil Butte Member (or FBM for short) of the Eocene Green River Formation. Many people interested in fossils know of the Green River Formation – we’ve all seen Green River Formation fossils in museums, in the literature, and on sale – but less familiar is how complex the stratigraphy is. There are 14 separate members, the formation as a whole was laid down over about 5 million years, the formation as a whole has an aerial extent of over 65000 square km, and in places is 600 m thick or more.

 I bet you want to see lots of drawings of fishes, right? Well then... click here. Image by Darren Naish.

Early chapters in the book review the age, geology and context of the location, the people involved in Fossil Lake’s discovery and excavation, and some background on generalities of classification and evolutionary history. Fossil bacteria, arthropods and other invertebrates are covered next, and then we come to the several chapters on vertebrates. Fishes are here in abundance, both cartilaginous and actinopterygian (hence the montage above, cough cough cough), and Grande describes and reviews what we know about the stingrays, gars, bowfins, pike and others of the FBM.

Squamates of the FBM. At left: the varanid Saniwa (photo by Smokeybjb, CC BY-SA 3.0). At right: Boavus (photo by Daderot, in public domain).

We then get to the tetrapods: there are turtles (baenids, trionychids and emydids), snakes (the ultra-rare Boavus and one or two other taxa are known) and lizards (the spectacular archaic varanid Saniwa, shinisaurids, and the iguanian Afairiguana). Crocodylians are known from the FBM, namely Borealosuchus (a taxon outside the crocodyloid-alligatoroid clade) and the small alligatorine Tsoabichi.

A near-complete FBM skeleton of a big Borealosuchus wilsoni. Image by Smokeybjb CC BY-SA 3-0.

The bird chapter is substantial enough to demand that anyone seriously interested in Cenozoic birds should obtain the book. As is well known, the FBM has yielded an impressive diversity, the taxa representing virtually all major neornithine clades. There are palaeognaths (like the lithornithid Pseudocrypturus), galloanserines, and early members of the lineages leading to modern nightjars, ibises, rollers, mousebirds, parrots and passerines. All are spectacularly illustrated, the photos sometimes being the best yet to appear in print.

Some of the taxa concerned – Gallinuloides, Fluvioviridavis, Foro, Prefica, Limnofregata, Primobucco – will be familiar to specialists, but there are surprises here nonetheless. An eocypselid swift in the FBM? A possible sunbittern? Then there’s the skull (only 55 mm long) of an unidentified raptor-like taxon. It looks vaguely like a cathartid.

Images of that giant feather don't seem to be available online (at least, not with an attached CC license), so I knocked up this semi-diagrammatic representation, traced from a photo. Possible Gastornis feather from Green River Formation, CC BY-SA 3.0
The classic, shaggy-plumaged version of Gastornis, from Matthew and Granger's 1917 paper. Filaments now thought to be plant fragments were misidentified at the time as Gastornis feathers. Incidentally, anyone know who the artist was? Image in public domain.

And – maybe most exciting for fossil bird nerds – a giant, broad-vaned feather, 240 mm long, that might belong to Gastornis. If it does, it could mean that the shaggy-plumaged look so traditional for this bird may be well off, as it looks as if the barbs may originally have been tidily connected to form a well defined shape. A few artistic life reconstructions of Gastornis have already incorporated this information (and note that our views on the life appearance of Gastornis should also take account of data indicating that it’s a galloanserine).

Anyway, the several stem-parrots, mousebirds, zygodactylids and so on paint a picture of busy lake-side canopies with high bird diversity and an abundance of available fruit. I’d love to see some artistic dioramas that depict this diversity – alas, there doesn’t seem to be anything out there, at least not anything modern (or is there?).

Undescribed flightless FBM salmilid. Image by Matt Mechtley, CC BY-SA 2.0.

Finally, there are the mammals. Again, Grande’s chapter combines an extensive, detailed text with spectacular colour photos. The FBM mammals fall into two groups. Several are early members of familiar living groups: there are the bats Onychonycteris and Icaronycteris, and a couple of early perissodactyls. But then there are taxa that belong to groups that don’t have any extant representation and which are generally regarded as Paleogene oddballs of uncertain affinity – pantolestids, apatemyids and hyopsodontids. Most remarkable is an incredibly long-tailed mammal said to be a cimolestid, its tail apparently has the highest vertebral count of any mammal known so far.

The book also includes chapters on plants, trace fossils and FBM taphonomy. The plant chapter – again, there is tons of text and a wealth of stunning images – surely contains enough information for anyone wishing to attempt a scientifically accurate reconstruction of the FBM palaeoflora.

A few glimpses of the inside of Grande's The Lost World of Fossil Lake. There's a good picture to text ratio, and I think virtually all of the photos are in colour.

The Lost World of Fossil Lake is fantastic, spectacular and satisfyingly detailed. It should be clear from this review that those seriously interested in the fossil taxa discussed above should obtain it, and so should those with a more general interest in the quality of the fossil record, in taphonomy and preservation, and in Cenozoic (especially Paleogene, especially Eocene) fossil history. Grande is not just a chronicler and reviewer of the fossils known from the locality, but a leading expert on them, his numerous publications being famously thorough, insightful and among the most useful of works published on the taxa concerned. Accordingly, the text is absolutely up to the date and contains information otherwise only available in the relevant technical papers. In other words, he really delivers the goods. I’ve already used this book extensively in my own technical work (for the… fish), but I’ve also enjoyed just flicking through it, the photos being so spectacular.

Lance Grande. 2013. The Lost World of Fossil Lake: Snapshots from Deep Time. The University of Chicago Press, Chicago and London. Hardback, index, pp. 425. ISBN 978-0-226-92296-6. $45.00/£31.50. Here on amazon.

For previous Tet Zoo book reviews (some of them pertaining to books shown in the photo at the very top of the article), see...