Stop Saying That There Are Too Many Sauropod Dinosaurs, Part 7

Welcome to part – oh my god – seven in this seemingly eternal series.

Like me, I’m sure you want it to end so I can get back to writing about the innumerable other things on the list. Yes, we’re here, once again, for another instalment in the Too Many Damn Dinosaurs (TMDD) series. If you’re new to the whole thing, go back to Part 1 and see what this is all about; if you want to see all previous parts in the series go to the bottom of the article for the links (or use the sidebar). In the most recent articles, we looked at two assumptions inherent to the TMDD contention: that sauropod populations were similar in structure to modern megamammal populations, and that sauropods and other big dinosaurs were similar to Holocene megamammals in ecology and distribution. Here, we look at a third assumption, and it’s one that just won’t die.

Caption: a somewhat ‘Mesozoic’ scene, photographed in the English westcountry in 2018. Ferns - including tree ferns like those shown here - and cycads of many sorts were available as sauropod food. Image: Darren Naish.

Caption: a somewhat ‘Mesozoic’ scene, photographed in the English westcountry in 2018. Ferns - including tree ferns like those shown here - and cycads of many sorts were available as sauropod food. Image: Darren Naish.

Ok, this article is the shortest one in the series. Here we go…

Assumption 3: Mesozoic plants were low in energy, and no way could all these sauropods derive sufficient nutrition to thrive at such diversity. Inherent to the TMDD contention is the idea that cycads, conifers and the other plants consumed by sauropods are and were so rubbish as sources of food that they couldn’t possibly be consistent with high megaherbivore diversity. This view has been mooted in particular by Prothero (2019, p. 111), who wrote “these many different huge herbivores had to subsist on slow-growing conifers, which are very low in nutrition and don’t recover quickly from heavy browsing, and possibly ferns and cycads on the ground”.

Caption: ginkgos were available as food to sauropods (albeit not the modern species Ginkgo biloba, shown here). Sauropods of many sorts could also have fed from the ground, on ferns and other ground-hugging species. Images: Darren Naish.

Caption: ginkgos were available as food to sauropods (albeit not the modern species Ginkgo biloba, shown here). Sauropods of many sorts could also have fed from the ground, on ferns and other ground-hugging species. Images: Darren Naish.

It’s true that some of the plants consumed by sauropods likely were relatively low in nutritional value. But quite what this has to do with megaherbivore diversity isn’t really clear, given that megaherbivores derive the energy they need from slow digestion of low-quality material: it’s a game of quantity over quality, and so long as quantity is sufficient (which it evidently was in the environments these animals inhabited), things are fine (Carpenter (2006) also pointed this out). In any case, the old ‘Mesozoic plants were low in quality’ adage is wrong, as anyone who’s been following Carole Gee’s research – and that of her colleagues – will know. Hummel et al. (2008) and Gee (2011) showed, following a series of experiments, that various conifers, ginkgos, ferns and horsetails of the Mesozoic were extremely nutritious, with Equisetum, monkey-puzzles and certain ferns being of similar nutritional value to grass (the most nutritious of modern plant foods), all being ‘five star superfoods’ according to Gee’s ranking. This research has been widely reported at conferences and is also discussed in Mark Hallett and Matt Wedel’s 2016 The Sauropod Dinosaurs (Hallett & Wedel 2016).

Caption: it’s easy to forget or under-estimate how abundant ferns must have been in parts of the Mesozoic world. Today, huge fern meadows are present in such places as England and New Zealand. This photo - take in southern England in December 2019 -…

Caption: it’s easy to forget or under-estimate how abundant ferns must have been in parts of the Mesozoic world. Today, huge fern meadows are present in such places as England and New Zealand. This photo - take in southern England in December 2019 - shows dead Braken Pteridium aquilinum during the winter. The quantity of fern biomass here might impress you - imagine what this scene was like when the plants were alive. Image: Darren Naish.

So much for that idea, then. Sauropods didn’t live in a world where available vegetation was of a quality similar to cardboard and bark. In fact, they were surrounded by highly nutritious foodstuffs of the sort that fuel animals like artiodactyls and geese, and there aren’t energetic reasons that are ‘against’ their high species- and genus-level diversity, nor against the sorts of population number we might predict given the logic outlined in previous articles in this series (Farlow et al. 2010).

Ok, we’re nearly at the end now – just one article in this series left to go. In the next section, we look at the issue of ‘appropriate expertise’ and then come up with a summarised list of key points in this debate.

For the previous article in this series, see…

For previous TetZoo articles on sauropods, brontotheres, giraffes and related issues (linking where possible to wayback machine versions), see…

And here's your reminder that the persistence and success of Tetrapod Zoology now depends entirely on funding via patreon. Thanks to those who support me! The more secure my funding, the more time I can and will spend generating content for Tet Zoo.

Refs - -

Carpenter, K. 2006. Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus Cope, 1878. New Mexico Museum of Natural History and Science, Bulletin 36, 131-137.

Farlow, J. O, Coroian, I. D. & Foster, J. R. 2010. Giants on the landscape: modelling the abundance of megaherbivorous dinosaurs of the Morrison Formation (Late Jurassic, western USA). Historical Biology 22, 403-429.

Gee, C. T. 2011. Dietary options for the sauropod dinosaurs from an integrated botanical and paleobotanical perspective. In Klein, N., Remes, K., Gee, C. T. & Sander, P. M. (eds) Biology of the Sauropod Dinosaurs. Indiana University Press (Bloomington and Indianapolis), pp. 34-56.

Hallett, M. & Wedel, M. J. 2016. The Sauropod Dinosaurs: Life in the Age of Giants. Johns Hopkins University Press, Baltimore.

Hummel, J., Gee, C. T., Südekum, K.-H., Sander, P. M., Nogge, G. & Clauss, M. 2008. In vitro digestibility of fern and gymnosperm foliage: implications for sauropod feeding ecology and diet selection. Proceedings of the Royal Society B 275, 1015-1021.

Prothero, D. R. 2019. The Story of the Dinosaurs in 25 Discoveries. Columbia University Press, New York.