Tetrapod Zoology

Tetrapod Zoology

Amphibians, reptiles, birds and mammals - living and extinct

The Wealden Bible: English Wealden Fossils, 2011


Finally, I have in my possession a copy of English Wealden Fossils, the massive, significant and long-awaited new volume published by the Palaeontological Association as part of its Field Guide to Fossils series (this is number 14 in the series). The volume is edited by David Batten and consists of 35 chapters on all aspects of Wealden palaeontology, from cockroaches and ostracods to pterosaurs, dinosaurs, mammals and more (Batten 2011).

This really is the ultimate volume on the Wealden that we’ve all been waiting for. The book actually had its genesis some considerable time ago (as far back as the 1980s, I believe) and clearly had a rather extended gestation, to say the least. It has been worth the wait.

For those who don’t know, the Wealden (technically, the Wealden Supergroup) is a complex Lower Cretaceous geological unit, deposited between Berriasian and Aptian times across western Europe. It consists of various sandstones, mudstones and siltstones, most of which were deposited by meandering rivers as they crossed floodplain and deltaic environments. Numerous beds within the Wealden yield fossils – most famously dinosaurs, but also diverse fish, plants, invertebrates and micro-vertebrates – and the major role that many of these fossils had in aiding our understanding of extinct life is well known (Gideon Mantell, Iguanodon, 1820s, blah blah blah). Outcrops along the south-eastern coast of England, and in inland quarries and other workings, continue to yield Wealden fossils, often representing new species. Needless to say, English Wealden Fossils only reviews the Wealden fossils of England – but that’s ok, since the vast majority of known Wealden taxa were described from England before they were discovered elsewhere in Europe.

English Wealden Fossils, with pickled leopard gecko and tape measure for scale.

At 769 pages, this is a substantial volume. It’s ‘compact’: c. 14 x 22 cm, and an impressive 4.5 cm thick. It weighs 2.9 kg and makes a satisfyingly loud thud when dropped on a table. My aim in this article is to briefly give you an idea of what the volume contains and to comment on features that are of special personal interest (hey, as I always like to say… this is my blog).

Before discussing the book’s contents, I want to say how impressive the production standards are. The hundreds of photos and diagrams are of excellent quality and extremely high in resolution. Quite a few of the photos (including many in the sauropod and plant chapters), maps and other diagrams are in colour. I also really like the fact that the text looks ‘dense’, is appropriate in font size relative to page size, and takes up most of the available space on each page: I really hate those books that waste vast quantities of white space around the edges of the text for no reason other than to increase the size and weight of the book, and to use up the maximum amount of paper (I’m referring here to technical books, not popular ones). The bibliography is over 70 pages long and the volume is fully indexed.

On to the volume’s technical contents... sticking to the tetrapods, of course. In recent years a substantial amount of new information has been obtained on the vertebrate microfauna of the Wealden and a large number of new taxa have been discovered; virtually all of this work has been spear-headed by the University of Portsmouth’s Steve Sweetman. Several chapters in the new book discuss and document this diversity: Steve worked with Susan Evans on the lissamphibian and lizard chapters (there are numerous new Wealden anurans and salamanders, and as many as ten new scincomorph lizards; though all are known from fragments), and with Jerry Hooker on the mammals (they include plagiaulacoid multituberculates, spalacotheriids, dryolestids, aegialodontids and gobiconodontids). The tiny theropod specimen that Steve and I documented in a recent paper (Naish & Sweetman 2011) came too late for me to include much data on it in the theropod chapter [reconstruction of this animal - the ‘Ashdown maniraptoran’ - shown below].

The Ashdown maniraptoran, from Naish & Sweetman (2011).

Moving now to other chapters, Wealden pterosaurs are reviewed by Dave Martill, Steve Sweetman and Mark Witton, and turtles by Andrew Milner. Hilary Ketchum reviewed the plesiosaurs (the chapter is called ‘marine reptiles’ - that isn’t really appropriate, since the Wealden taxa inhabited freshwater, lagoonal or quasi-marine environments. To be fair, however, Hilary does note that ‘marine reptile’ is used simply as a convenient vernacular term for the respective groups). I’m particularly interested to know that – at last – there are ichthyosaurs in the Wealden… though, alas, they’re just two indeterminate vertebral fragments (Ketchum 2011). Several plesiosaurs have been named from the Wealden, the best known of which is Leptocleidus superstes from the Weald Clay of East Sussex, recently reviewed by Kear & Barrett (2011). I’ll be saying a lot more about Wealden plesiosaurs some time fairly soon.

Then there are the crocodilians. Steve Salisbury and I worked together to produce what is effectively the first ever comprehensive review of Wealden crocs (Salisbury & Naish 2011). For, while the dinosaurs and some other groups have been reviewed umpteen times, the crocodilians have remained in a bit of a mess and what was meant to be a brief summary turned into a major technical review more than 60 pages long in which three new species are named (the goniopholidids Goniopholis willetti and Anteophthalmosuchus hooleyi, and the mysterious, weird neosuchian Leiokarinosuchus brookensis). I’m intending to discuss this work at length some time soon.

Iguanodonts!!! Colour restorations by Steveoc 86 (from Wikipedia) and skull reconstructions by Greg Paul ©, used with permission.

Each of the major dinosaurian groups gets a chapter. Paul Barrett and Susannah Maidment’s thyreophoran chapter includes new information, some of which might show that Polacanthus has a range extending into the Valanginian (Barrett & Maidment 2011). David Norman’s ornithopod chapter includes the latest round of his efforts to show that Paul, Carpenter and Ishida were wrong in their naming of Dollodon, Sellacoxa and so on; he refers a lot of material (including the holotype of Kukufeldia) to Barilium and Hypselospinus (Norman 2011a). I’m not confident about the reliability of many of these referrals given the absence of overlapping material (how do you know, for example, that a jaw bone belongs to a species originally named for an ilium?), but nevertheless these referrals represent viable hypotheses. Incidentally, Norman’s osteology of all the type and referred Barilium material has recently been published elsewhere (Norman 2011b). Norman agrees with Naish & Martill (2008) that the Valanginian dryosaurid material may indeed represent a new taxon. Note also that substantial material of the Wealden dryosaurid Valdosaurus has just been described elsewhere by Barrett et al. (2011). This latter study is significant in finding that Valdosaurus is closer to the African dryosaurids Elrhazosaurus and Dysalotosaurus than to the North American Dryosaurus [for more on dryosaurids, see Dryosaurids 101].

MIWG 7306, a large brachiosaurid cervical vertebra from the Wessex Formation of the Isle of Wight. Due to, err, advice from a co-author, these diagrams were not included in the descriptive paper (Naish et al. 2004).

Paul Upchurch, Philip Mannion and Paul Barrett review the sauropods in an appropriately lengthy, thorough review. They take previous authors (Naish & Martill 2001) to task for erroneously suggesting that several Wealden sauropods might be brachiosaurids when there’s no good evidence for this. Furthermore, they suggest that Xenoposeidon (Taylor & Naish 2007) might be a symphospondyl (Upchurch et al. 2011) (but, don’t get me wrong from these statements: I’m not in any way unhappy with their conclusions). Wealden sauropod diversity includes rebbachisaurids, brachiosaurids in (apparently) the strict sense, non-brachiosaurid, non-titanosaurian titanosauriforms, titanosaurs, and some enigmatic forms that can’t be placed anywhere with confidence. That’s a fairly impressive diversity for the Early Cretaceous, consistent with views that Northern Hemisphere sauropods weren’t obviously doomed to oblivion at the close to the Jurassic and in fact were not doing all that badly during the first half of the Cretaceous at least (Taylor et al. 2010).

In producing Dinosaurs of the Isle of Wight during 2000 and 2001, I always felt that there were contradictory signals on what to do with all the Wealden sauropods. On the one hand I had people advising me quite strongly to reduce the number of Wealden sauropods as much as possible, since (a) they were all ‘clearly’ different bits of the same, brachiosauridy-type animal, and (b) it really isn’t possible that so many mega-herbivores could have lived alongside one another. On the other hand, my personal opinion is that (a) you can’t synonymise taxa just because they happen to come from the same formation (cough iguanodontians cough), and (b) palaeontologists who specialise on the Mesozoic frequently have a poor grasp of how many species might be expected to be contemporaneous in a given fauna, and that the idea of three, four, five or six contemporaneous giant herbivores is not really a problem so long as the ecology, terrestrial area, climate and so on is consistent with this. Whatever, I don’t think Naish & Martill’s (2001) review fares too badly in view of Upchurch et al.’s (2011) new analysis – the primary issues are that we didn’t consider the possibility that there might be rebbachisaurids in the Wealden, and our concept of ‘Brachiosauridae’ more or less corresponded with ‘basal titanosauriform’ more than with ‘brachiosaurid’ in the strict sense.

Martill & Naish's 2001 Dinosaurs of the Isle of Wight. Written back when I should have been working hard on my PhD.

I’d also like to add here that Dave Martill and I produced Dinosaurs of the Isle of Wight in an incredible hurry. That’s no excuse for the many mistakes that made it into the volume* – there’s crap in there like Echinodon masquerading as Hypsilophodon, a famous East Sussex Iguanodon specimen is labelled as being from the Isle of Wight, and there’s the mislabelling of the Ornithopsis holotype (I’ll blame whoever was taking the photos and writing down the specimen numbers, har har), but it does explain why some of those mistakes were made. I plan to reminisce at length about the whole adventure behind the writing of Dinosaurs of the Isle of Wight, incidentally. But, then, I plan lots of things.

* My personal copy is heavily annotated and I used to toy with the idea of producing a revised edition.

Finally, we come to the theropod chapter (Naish 2011). Wealden theropods include Baryonyx, Neovenator, Eotyrannus and a load of taxa based on fragmentary bits and pieces. I’d like to think that this chapter represents a sort of last word on the tangled mess that is Wealden theropod diversity, but sadly it doesn’t. Firstly, I still have to publish the Eotyrannus monograph (I’m working on it). Secondly, the identifications proposed for certain of the fragmentary remains (like Thecocoelurus and the so-called ‘Calamosaurus’ tibiae) might get revised still in view of new material from elsewhere in Europe. Indeed, I’m becoming increasingly cagey about pinning precise identifications on such things as isolated vertebrae, bits of limb bones and so on – even when you find convincing characters that seem, well, convincing, it can later turn out that, say, cervical vertebrae of a certain type evolved more than once within the clade in question. Huh, I sound like a Triassic worker. More on this later. And let’s not mention a certain fossil from Kazakhstan. Yet. Anyway, after appropriate advice, I’ve toned down my enthusiasm about the similarities between Becklespinax and Concavenator: Becklespinax might be a carcharodontosaurian, but there aren’t enough characters to be sure. My chapter includes skeletal reconstructions by the brilliant Ville Sinkkonen and Scott Hartman. [Wessex Formation scene below by Mark Witton; for bigger versions go here].

A busy day in Barremian southern England (the taxa shown represent those discovered in the Wessex Formation). Image by Mark Witton.

So, there we have it. Regular readers might know that I tend to describe many books as ‘must have’ volumes, and partly that’s because I’m one of those crazy completist collector types of people, but on this occasion I don’t think there’s any doubt that it’s absolutely mandatory for anyone interested in Lower Cretaceous terrestrial faunas to get hold of this volume. Those interested in dinosaurs in general, or in Cretaceous amphibians, squamates or crocodilians, will also need this volume. The tetrapod content is substantial, but remember that there are also sections on molluscs, arthropods, plants, fish and geology and stratigraphy. Echoing recent comments I made in my review of Hans Sues’s and Nick Fraser’s Triassic Life on Land, the chapter on plants looks really useful in providing lots of images of fronds, leaves and other plant macrofossils: the sort of images you need in identifying fossils, but also when trying to accurately reconstruct Mesozoic landscapes.

The good news is that – for once – this massive volume is incredibly, unbelievably affordable: it’s just £24 [US$37] (£16 [US$25] for Pal Ass members). It can be ordered from the Pal Ass site here.

For previous Tet Zoo articles on Wealden dinosaurs, see...

Refs - -

Barrett, P. M., Butler, R. J., Twitchett, R. J. & Hutt, S. 2011. New material of Valdosaurus canaliculatus (Ornithischia: Ornithopoda) from the Lower Cretaceous of southern England. Special Papers in Palaeontology 86, 131-163.

- . & Maidment, S. C. R. 2011. Armoured dinosaurs. In Batten, D. J. (ed.) English Wealden Fossils. The Palaeontological Association (London), pp. 391-406.

Batten, D. J. (ed.) 2011. English Wealden Fossils. The Palaeontological Association, London.

Kear, B. P. & Barrett, P. M. 2011. Reassessment of the Lower Cretaceous (Barremian) pliosauroid Leptocleidus superstes Andrews, 1922 and other plesiosaur remains from the nonmarine Wealden succession of southern England. Zoological Journal of the Linnean Society 161, 663-691.

Ketchum, H. F. 2011. Marine reptiles. In Batten, D. J. (ed.) English Wealden Fossils. The Palaeontological Association (London), pp. 285-294.

Naish, D. 2011. Theropod dinosaurs. In Batten, D. J. (ed.) English Wealden Fossils. The Palaeontological Association (London), pp. 526-559.

- . & Martill, D. M. 2001. Saurischian dinosaurs 1: Sauropods. In Martill, D. M. & Naish, D. (eds) Dinosaurs of the Isle of Wight. The Palaeontological Association (London), pp. 185-241.

- . & Martill, D. M. 2008. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: Ornithischia. Journal of the Geological Society, London 165, 613-623.

- ., Martill, D. M., Cooper, D. & Stevens, K. A. 2004. Europe’s largest dinosaur? A giant brachiosaurid cervical vertebra from the Wessex Formation (Early Cretaceous) of southern England. Cretaceous Research 25, 787-795.

Naish, D., & Sweetman, S. C. (2011). A tiny maniraptoran dinosaur in the Lower Cretaceous Hastings Group: evidence from a new vertebrate-bearing locality in south-east England. Cretaceous Research, 32, 464-471

Norman, D. B. 2011a. Ornithopod dinosaurs. In Batten, D. J. (ed.) English Wealden Fossils. The Palaeontological Association (London), pp. 407-475.

- . 2011b. On the osteology of the Lower Wealden (Valanginian) ornithopod Barilium dawsoni (Iguanodontia: Styracosterna). Special Papers in Palaeontology 86, 165-194.

Salisbury, S. W. & Naish, D. 2011. Crocodilians. In Batten, D. J. (ed.) English Wealden Fossils. The Palaeontological Association (London), pp. 305-369.

Taylor, M. P. & Naish, D. 2007. An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England. Palaeontology 50, 1547-1564.

-., Wedel, M. J. & Cifelli, R. L. 2011. Brontomerus mcintoshi, a new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA. Acta Palaeontologica Polonica 56, 75-98.

Upchurch, P., Mannion, P. D. & Barrett, P. M. 2011. Sauropod dinosaurs. In Batten, D. J. (ed.) English Wealden Fossils. The Palaeontological Association (London), pp. 476-525.

The views expressed are those of the author and are not necessarily those of Scientific American.

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