Dinosaurs were not only carnivorous (Theropoda) but some of them were almost entirely herbivorous such as Sauropodomorpha and Ornithischia. The dietary preference is determined by various factors including tooth morphology, jaw mechanics, and tooth wear facets. The only way to assume dinosaur’s diet is to understand its thermal physiology, the amount of food required by it; what the internal food organ is composed of, and how they might have functioned. Sounds interesting, continue reading to know what did dinosaurs eat and learn about their diet and feeding behavior.
What Did Dinosaurs Eat
Like pandas many herbivores and carnivores have adapted to living on a wide variety of food items which rarely seems incompatible with their skeletal characteristics.
It’s hard to get the results of dinosaur’s diet from their fossil records because these fossils are not good enough to show dinosaur’s age, social organization, habitat preference, and the availability of food. All these factors are vital to determine dinosaur’s diet. This explains why we must take all rumors about their diet with an absolute caution.
Dinosaurs are believed to have evolved in the Early Triassic period from carnivorous ornithosuchid ancestor. The oldest known ornithischian is Pisanosaurus mertii and its closely packed teeth suggest that they might have been herbivores.
Diet of Theropoda
The typical dinosaurian carnivore is a bipedal theropod. They used to have strong legs designed for running as well as long forearms designed to manipulate its prey. There is a wide gap in their jaws which is composed of large number of compressed teeth.
Almost all these carnosaurs seem to be active predators for they could locate, track, and possess suitable hunting techniques but the size of its prey is still under discussion.
Tyrannosaurids of the Late Cretaceous used to be of the same size as of their prey but they sometimes they could be larger. Allosaurs on the other hand were ten times smaller than adult sauropods. They belonged to the Jurassic times. Allosaurs used to feed either on young sauropods, campotosaurs, or stegosaurs or they developed a technique to hunt down adult sauropods. According to Auffenberg (1981) Allosaurus’ teeth functioned in much the same way as the canines of saber-tooth cats do.
Research indicates that Allosaurus employed a ‘hit-and-run’ technique in that they could inflict deep wounds on its prey and then they back away waiting for its prey to give away its wounds.
Evidence seems to suggest that few theropods hunted prey (sauropods) in packs.
Prominent among the large carnivores were Giganotosaurus or Tyrannosaurus rex which could have been rather active predators if there were other carnivores but their large size might have intimidated these other carnivores leaving them merely scavengers. Alongside ‘hit-and-run’ attack a few theropods appear to have choked its prey by clamping their jaws onto prey’s neck.
Many theropods seemed to possess powerful mandibular adductors which made a strong bite. Erickson (1996) reported multiple bites of T. rex on Triceratops pelvis. The research also indicated that T. rex had the greatest bite force measuring up to 13,400 N.
Tooth shape in Carcharodontosaurus and tooth and jaw shape in Baryonyx and Spinosaurus indicates that these dinosaurs may have been piscivorous.
Hind limbs of nearly all theropods are same in shape and function the same way. The femur is normally shorter as compared to tibia and is designed for quick running. They possess three-toed feet (except in therizinosaurids) alongside terminal claws that could have helped in killing of prey.
Ceratosaurs, coelurosaurs, and maniraptorans have relatively long and powerful forelimbs that allow them to seize prey. All in all theropods take on large prey items which they grasp with both hands while ripping off with their powerful claws. They might not have hunted in packs for if they did, then there should not be any prey item too large for them.
Troodon formosus is believed to have fed on small nocturnal mammals including lizards. They are crepuscular.
The study suggests that the animals which young theropods feed on are different as compared to those which they hunt as adults. Besides they also employ different unique hunting strategies such as hunting in packs (young) versus solitary hunting (adult). The young are much slender than adults and probably much faster too. They were active hunters no matter what the hunting style was. They used to feed on small vertebrates and invertebrates.
Ornithomimosauria and Oviraptorosauria were two of the few theropods whose jaws were covered in a horny beak. Ornithomimids had weak jaws which led us to believe that their diet consisted of insects and small mammals.
The jaws of Oviraptorids are powerful enough to generate a strong bite. They used to feed on small mammals, insects, eggs, and small lizards.
Diet of Sauropodomorphs and Ornithischians
All Sauropodomorphs and Ornithischians seemed to have an absolutely herbivorous diet. They are classified into two categories; mouth processors and gut processors. Gut processors are adapted to digest low-nutrition and high-fiber plants. Fermentation in the gut would have further divided into the fibrous plant material and produced nutrients that later were absorbed by the host. Mouth processors were more likely to grind high-nutrition or low-fiber foods.
Prosauropods and many ornithischians had had possessed cheeks that facilitated them to have mouth filled with food while processing.
Dinosaurs in the Late Triassic may have relied on plants such as large arborescent, herbaceous lycopods, Brachyphyllum, and small herbaceous horsetails. Their diet also composed of ferns, true cycads, cycadeoids, ginkgos, conifers, and the seed fern order Caytoniales.
The sauropods were the dominant herbivores in the Early Cretaceous and the Jurassic.
Many sauropods might have consumed a large quantity of plant matter.
Giant sauropods and Prosauropods are believed to be gut processors while Massospondylus, Sellosaurus, and Seismosaurus are gastroliths. They had a skull that is built of weak muscles. Prosauropods had narrow and closely spaced teeth which explained that they could eat soft plants.
Prosauropods could also reach plants as high as 3 meters which made them the high-browsing animals of the Triassic. They seemed to feed on lycopsid fructifications. Similarly, the subsequent sauropods had elongated necks which helped them to reach out high plants. Prominent among the sauropods were Apatosaurus and Diplodocus which could reach browse as high as 18 m above the ground.
Thyreophora include ankylosaurs, stegosaurs, and their basal relatives Scelidosaurus, Scutellosaurus, and Emausaurus. Thyreophorans were exclusively gut processors and as it turned out they were likely to feed on low-lying plants (hardly 1 or 2 m above the ground). Many authors are of the view that these dinosaurs ate soft plants which might have composed of fleshy parts of caytonialian inflorescences, bennettitalian, and nilsonnialian.
References
Bakker, R. T. (1978). Dinosaur feeding behavior and the origin of flowering plants. Nature 274, 661–663.
Bonaparte, J. F. (1976). Pisanosaurus mertii Casamiquela and the origin of the Ornithischia. J. Paleontol. 50, 808–820.
Currie, P. J., Koppelhus, E. B., and Muhammad, A. F. (1995). ‘‘Stomach’’ contents of a hadrosaur from the Dinosaur Park Formation (Campanian, Upper Cretaceous) of Alberta, Canada. In Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Short Papers (A. Sun and Y. Wang, Ed.), pp. 111–114. Beijing, China.
Erickson, G. M., Van Kirk, S. D., Su, J., Levenston, M. C., Caler, W. E., and Carter, D. R. (1996). Bite-force estimation for Tyrannosaurus rex from tooth marked bones. Nature 382, 706–708.
Farlow, J. O. (1976). Speculations about the diet and foraging behavior of large carnivorous dinosaurs. Am. Midland Nat. 95, 186–191.
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