Hi Paul

Fossil Coprolites or Dinosaur Dung can provide valuable piece of evidence for vegetarian diet of a herbivorus dinosaur. Please see dinosaurs.about.com

There were some interesting ideas by Thomas Tütken about the application of stable isotops (13C) to learn something about dinosaur diets:

- Tütken, T. 2011, the diet of sauropod dinosaurs: implications of carbon isotope analysis on teeth, bones, and plants. pp. 57-79 in Biology of the Sauropod Dinosaurs Understanding the Life of Giants, (eds.) Klein, N., Remes, K., Gee, C.T., Sander, P.M. Indiana University Press Bloomington and Indianapolis

- Tütken, T., Pfrentzschner, H.-U., Vennemann, T.W., Sun, G., Wang, Y.D. 2004 Paleobiology and skeletochronolgy of Jurassic dinosaurs: implications from the histology and oxygen isotope compositions of bones. . Palaeogeography, Palaeoclimatology, Palaeoecology 206: 217-238

- Tütken, T., Sander, M., Hummel, J., Gee, CX. 2007, Ernährung und Mobilität von Sauropoden -Informationspotenzial der Isotopenzusammensetzung von Knochen und Zähnen. Hallesches Jahrbuch für Geowissenschaften Beiheft 23: 1-8

Here are some other papers about dinosaur and plant evolution/plant choices:

- Barrett, P.M., Willis, K.J. 2001, Did dinosaurs invent Flowers? Dinosaur-angiosperm (1): coevolution revisited. Biological Reviews 76: 411-447

- Sander, P.M., Gee. C.T., Hummel, J., Clauss, M. Mesozoic Plants and Dinosaur Herbivory. pp. 331-359 in: Gee. C.T. [ed.]: Plants in Mesozoic Time: Innovations, Phylogeny, Ecosystems (Theodore Delevoryas festschrift). (Indiana University Press) Bloomington.

- Zanno, L.E., Makovicky, P.J. 2011, Herbivorous ecomorphology and specialization patterns in theropod dinosaur evolution. PNAS 108 (1): 232-232

- Clauss M., Steuer P., Müller D.W.H., Codron .D, Hummel J. 2013, Herbivory and Body Size: Allometries of Diet Quality and Gastrointestinal Physiology, and Implications for Herbivore Ecology and Dinosaur Gigantism. PLoS ONE 8(9): e68714. doi:10.1371/journal.pone.0068714

Examples of more engineering based approaches (there are several more put there, but often they only mention general food preferences, like soft vs. hard plant material, or high browsinf vs. lw browsing):

- Barrett, P.M., Rayfield, E.J., 2006, Ecological and evolutionary implications of dinosaur feeding behaviour. TRENDS in Ecology and Evolution21 (4): 217-224

There are reported fossilized gut contents, but we have to be very careful in interpreting them, because the material often could have been introduced by water post mortem (just like a lot the reported gastroliths in dinosaurs.

And there are of cause more specialized answers derived from other anatomical studies. For example the habitual head postures (inferred from the orientation of the inner ear) and the extreme high tooth replacement rate in combination with an dentition that is almost limited to the rostral portion of the jaws point toward a low- to (in lesser extreme cases) mid-level browsing height in diplodocoid sauropods. Their diet would likely include a high amount of the energy rich but also highly abrasive horsetails. The high browsing Tendaguru sauropd Giraffatitan on the other hand most likely fed on Cheirolepidiaceae, Podocarpaceae, Araucariaceae and other Conifers.

Coprolites from the uppermost Cretacous that are ascribed to sauropods contained grass phytolithes:

Prasad V., Strömberg, C.A., Alimohammadian, H., Sahni, A. 2005, Dinosaur coprolites and the early evolution of grasses and grazers. Science. 2005 Nov 18;310(5751):1177-80.

Hi Paul: What an interesting discussion question—coincidentally, I have looked into exactly this question from a paleobotanical and animal nutritional point of view.  The larger herbivorous dinosaurs may have eaten cycad fronds as a minor part of their diet, just because they were bulk feeders and needed to eat all the greenery that they could.  However, cycad leaves (now and likely then) provide very little energy and biomass to herbivores, and are full of nerve toxins.  Thus, cycads would probably not have been a herbivorous dinosaur's first choice.  It would have been the same for smaller herbivorous dinosaurs, in which the effect of the nerve toxins would have been even stronger.  Have a look at my paper (Gee, C. T.  2011.  Dietary options for the sauropod dinosaurs from an integrated botanical and paleobotanical perspective.  In: N. Klein, K. Remes, C. T. Gee, and P. M. Sander (eds.), Biology of the Sauropod Dinosaurs: Understanding the Life of Giants.  Indiana University Press, Bloomington, pp. 34-56.) in which I discuss the issue of which plant groups were likely most preferred by large herbivorous dinosaurs (i.e., sauropods) and cite recent papers on this topic.  You should be able to download it from Researchgate.  If not, send me your email address, and I will send it to you.  Best, Carole

As Carole Gee noted, the high toxicity of cycad leaves makes it unlikely that any reptile consumed this foliage. Indeed, the presence of virulent neurotoxins in all genera of modern cycads suggests these substances evolved early in the evolutionary history of these plants as a defense against predation by herbivores. However, the reproductive strategies of cycads is evidence of coevolution. The highest level of toxins are found in cycad seed kernels, but these seeds are enclosed in a thick coating of edible tissue (more or less like a modern plum or apricot in size and form). Thus, cycad seeds were an attractive treat for dinosaurs like prosauropods, sauropods, and and stegosaurs, which used their peg-like teeth to rake in vegetation that was swallowed with little chewing. Seeds remained intact, so toxins were not released, and the dinosaurs provided an efficient mechanism for transporting the fertile seeds. Extinction of dinosaurs left cycads without an effective means of seed dispersal, a major factor in their Cenozoic decline.   Details of this interpretation can be found in my 2007 paper "Coevolution of cycads and dinosaurs", which appeared in Cyad Newsletter, Volume 30, number 1. You can download the PDF on my ResearchGate site: https://www.researchgate.net/publication/266138574_Coevolution_of_cycads_and_dinosaurs

Best wishes, George

Article Coevolution of cycads and dinosaurs

There ar a few other interesting papers using stable isotopes as proxies for diet and other ecological factors in dinosaurs:

- Fricke, H.C., Rogers, R.R., Gates, T.A. 2009, Hadrosaurid migration: inferences based on stable isotope comparisons among Late Cretacous dinosaur localities. Paleobiology 35 (2): 270-288

- Fricke, H.C., Pearson, D.A. 2008, Stable isotope evidence for changes in dietary niche partionig among hadrosaurian and ceratopsian dinosaurs of the Hell Creek Formation, North Dakota. Paleobiology 34 (4): 534-552

- Stanton Thomas, K.J., Carlson, S.J. 2004, Microscale d18O and d13C isotopic analysis of an ontogenetic series of the hadrosaurid dinosaur Edmontosaurus: implications for physiology and ecology. Palaeogeography, Palaeoclimatology, Palaeoecology 206: 257-287

More generally I would say herbivore dinosaur (I suppose you think about non-avian dinosaurs) had a massive impact on vegetation. Just the amount needed by the larger species should keep an check on and shape the vegetation and floral communities these creatures lived in. The concept of the Mammut-Steppe comes t my mind. Or more general: the whole biom that supported such organism was likely self supporting and self created in a sense that without the megaherbivors the whole landscape would turn into a different biom. Much like the savanna of modern Africa.

On the other hand it is very hard to thing of true analogs to sauropods in these days. The impact of their foraging may have been comparable to elephants but their digestion seems to have been much more effective, much more like in ruminants (but with a total different mechanism that involved very long retention times).

There are some many excellent answers that it is difficult to give a thumbs up to just one of them. The discussion brings up some unaswered questions such as: Did the dinosaurs have an immunity to the toxins of cycads.  There  was so much cycads to eat,  why would not dinosaur evoluition have not developed some such ability during the course of their evolution? Feeding height stratification is an interesting point, but why did they not eat ferns and other lower vegetation? I do not know if there was tree ferns during the Mesozoic, butt I suspect there were.  They would provide plenty of fronds for dinosaurs to eat. The idea of studying coprolites is a very good approach, except that the preservation would not be great.  Isotope geology is an interesting approach but  there would be many assumptions to work with. The relationship bektween nutrition and teeth seems like a legitimate one. I dont know how much of the biomass of Mesozoic vegetation consisted of horsetails. This would be a limiting point, of course.

dear Paul,

May be there were so many Cycads around because they were not eaten!

But I have had a coprolite with leaf remains (cuticles) of a Ptilophyllum species, and Ptilophyllum is a Bennettitalean plant.

I also had smaller coprolites with Sagenopteris/Vitreisporites pollen (coming from the same plant in the Caytoniales), just like the other one in the Jurassic of Yorkshire. Preservation was good in those cases.

and finally, we had a large coprolite (size of poo from a large dog) from the Cretaceous which was completely full of Cheirolepidiaceous remains.

so coprolites are a good base for study, just as feeding traces on plants

Dear Johanna,

Thank you  so much for those fine examples of preservatioon of cycads in coprolites in the Mesozoic. You have shown that cycads and other vegetation were indeed eaten and preserved.in coprolites.  Thanks so much. Best wiishes. Paul.

Dear Johanna, I was wondering if you could get word to my old friend, Dr. Miente Boersma, that I had said hello and  extend my best wishes to him and his wife. Thanks in advance. Paul.

dear Paul,

I am afraid that I cannot do that. We have lost contact with Miente Boersma since ca. 1995; we do not even know where he lives! His third wife divorced him and he moved out of their house. He quit palaeobotany, that I now.

I have heard that he is back in music, but I never saw him again.

Han

Dear Han,

If you ever come across a way to contact him, I would  appreciate knowing. He is a good friend. Best wishes, Paul

dear Paul,

here is Miente's linkedIn page:

https://nl.linkedin.com/pub/miente-boersma/2a/8a1/9a9

as I am not on LinkedIn, I cannot access it, but may be you can!

all the best

Han

Paul,

The coprolite evidence refers to Bennetittales, which are not cycads, they are simply two look-alike plant groups. The term "cycadophytes" is sometimes used to include both groups, and in popular terminology they are often both erroneously called "cycads". Because there are no living Bennettitales members, we have no idea as to their toxicology, but certainly some dinosaurs were able to eat them. As for cycads, a reason why dinosaurs could not evolve a tolerance to the toxins is that  cyads were also continually evolving to maintain their defenses.  Perhaps more important, all creatures have to work within the limits of their  basic genetic pattern. For example, as handy as it would be for playing the piano or for  home repair projects, we can't evolve a third arm and hand. For basic biological characteristics, like the nervous system, there is no easy way change the basic biochemistry to provide a defense against potent neurotoxins. As for availability of potential food resources, it would be handy if humans could graze like cows or eat wood  like termites, but we fundamentally lack the digestive capacity to process these materials, and evolution doesn't  give us much hope of acquiring that ability.

George