Nigel Chaffey… and now to … dinosaurs (!). Dinosaurs? Well, we did say at the outset of this mini series of articles that ‘seeds and animals’ was a very old association. Unlike the other animal associations mentioned already in this collection, it’s not possible to get direct evidence of seed dispersal by dinosaurs because they are no longer amongst us. Therefore, more indirect, circumstantial, evidence is needed to support assertions that dinosaurs were involved in seed dispersal in prehistoric times. Such evidence could be finding seeds amongst fossilized dinosaur droppings (coprolites).*
But there then may be some doubt as to the identity of the dung-depositing dinosaur. Less dubious is the question whether seeds are found within the stomachs of these animals, a question that underlies how Leonardo Salgado et al. have deduced seed-dispersal behaviour of a newly-described dinosaur. Named Isaberrysaura mollensis (which is not only a new species, but also a new genus of these beasts) this dinosaur lived in the Los Molles region of Argentina approx. 185 millions of years ago (from the Jurassic geological period).
Although the article considers features of the animal that are of more importance to dinosaur enthusiasts, from a botanist’s perspective the most interesting finding is what they unearthed in its guts – seeds of cycads.** To cut a long – but fascinating! – story short, the team infer that the dinosaur was involved in dispersal of these cycad seeds. However, until it can be established that the seeds survived passage through the intestines of these animals and emerged from the other end in a viable state such that they could germinate, and grow, then it’s not definitive proof of ‘dinochory’. But, until we have proof that this is not the case, it remains a likely scenario. Which goes to show that it’s not just seeds of angiosperms that animals – may! – help to disperse, but those of gymnosperms too (and that the animal-seed dispersal association is indeed an ancient phenomenon).
To extend this dinosaur-seed connection further, it has even been proposed that consumption of seeds – granivory *** – was a key ecological trait that enabled the survival of Neornithes during the mass extinction at the end of the Cretaceous period when non seed-consuming relatives became extinct. In this way, diet is viewed as an ‘extinction filter’. And the relevance of this to the modern day is that this group of dinosaurs are widely acknowledged as being the ancestors of our present day birds [12], which diverse group of avian diners frequently eat seeds and help to disperse them (with which animals we began our compendium in Part 1).
Well, that’s the last [for now!] in this series that aims to give some insight into the many animal taxa exploited by plants to spread their seed far and wide – and reminds us of the ‘mind games’ that plants play with more inferior lifeforms. Cheers!
* Though how can you tell that the disseminules/seeds weren’t planted amongst dinosaur poo by some mischievous entity wishing to confuse future palaeoturdologists..? Or, and maybe even more irritating, what if seeds that have successfully negotiated the dinosaur’s gut and emerged in the faeces were removed by prehistoric ants so this method of dinosaur seed dispersal is under-recorded and therefore under-appreciated? If you still doubt that this latter suggestion is a possibility, consider the kleptocoprophilial actions of modern-day humans who regularly pluck the coffee ‘beans’ out of the faeces of civet cats to make kopi luwak, the world’s most expensive coffee!
** These gut-residing remains, or trace fossils, are called cololites.
*** Which term shouldn’t be confused with grannivory, the consumption of female grandparents as practised – allegedly! – by certain wolves in Fairy Tales…
[This is part 6 of a series celebrating the creatively imaginative and enterprising ways in which plants dupe poor unsuspecting animals into doing their sexual bidding…]
AJ Cann
