top of page
  • Lim Yi Zheng (Nicholas)

On The Eating Habits of Megalosaurus

Updated: Dec 3, 2023

Edited by Amelia Gross.


Abstract

This research delves into the dietary habits of Megalosaurus, one of the earliest scientifically described dinosaurs. By analyzing the skull morphology and comparing it to other theropod dinosaurs, this study aims to infer Megalosaurus' bite capabilities and, consequently, the types of prey animals Megalosaurus would have preferably targeted.

Traditionally, Megalosaurus has been compared to Allosaurus, another theropod dinosaur, to theorize the appearance of the skull and, by extension, the bite force. However, it has now been rectified that the discrepancy in evolution between these two tyrants would have led them to favor dissimilar prey. Due to its inability to maintain high bite force along the tooth row (Sakamoto, 2010), it is now suggested that Megalosaurus could not employ bone-cracking techniques like the Tyrannosaurus.

Megalosaurs, in general, had highly efficient jaw mechanisms and high mechanical advantage. Nonetheless, their actual bite force would not be very high; in stark contrast to Allosaurus, their skulls were unlikely to resist high stress, which is a similar condition seen in Carcharodon thesaurus. Unlike the latter, the megalosaur’s teeth show a teardrop matrix that does not cut efficiently into flesh, which is compensated for by a robust build to provide inertia to pull back the head for slicing as well as an air sac near the cheek (Benson, 2010) to compensate for the high consumption of ATP that comes with this highly inefficient action.

All of these traits suggest that the primary prey making up the diet of Megalosaurus would have been stegosaurs, which were present in Stonesfield (Galton, 2017). Additionally, the sauropod Cetiosaurus Oxoniensis (Upchurch and Martin, 2003), could have also been potential prey. This aligns with the ecological trends repeated across the globe of giant Sauropods being preyed on by large theropods, although such hunts would likely have been more occasional, involving several individual Megalosaurus targeting sick, young, and injured animals, or engaging in scavenging behavior.

Introduction

The official species, Megalosaurus bucklandii, carries the distinction of being the world’s first scientifically described dinosaur, yet much about its physiology remains unknown due to the poor preservation state of such fossils. In recent years, much of what is known of this creature comes from extensive studies by Roger Benson, who, in 2008, provided the most detailed description possible of the known material, including identifying several distinct autapomorphies in the cranial elements. Some of Benson’s work connects certain features to other theropod dinosaurs, which gives a baseline for interpreting additional evidence from related species

All of this secondary information has been evaluated and further investigated to give an accurate portrayal of a solitary Megalosaurus in its role as a predator. A short documentary, accompanied by supplementary content illustrating potential prey items such as beach carcasses (Razzolini, Oms, and Castanera et al., 2016), aims to showcase Megalosaurus as a capable predator while exploring the adaptations that may have enabled it to capture prey effectively.


Techniques

In the pursuit of evidence supporting the claim that Megalosaurus possessed a relatively weak bite, this study extensively examined distinctive skull features and referred to a study made by Manabu Sakamoto in 2010 on the evolution of biting performance in theropods.

Practical experiments were conducted to investigate the potential impact of tooth shape on killing techniques. For these trials, a resin cast of an actual tooth was created. To test the ramifications of the tooth shape, the cast was stabbed into a block of plasticine and pulled backward at arm’s strength to mimic neck motion.

Figure 1. The reconstructed skull of Megalosaurus presented here is a product of a comprehensive self-research. The above diagram was inferred from all known cranial material and that of the closely related genus, Torvosaurus. (Image credit: self)


Given the necessary resources and access, a prospective for enhancing the research techniques would involve employing finite element analysis (FEA) to enable precise measurements of the stress tolerances exhibited by such a skull structure, as well as providing insights into the maximum force achievable by the lower jaws. This advanced analytical tool could offer a deeper understanding of Megalosaurus' biomechanical capabilities.


Results

The scrutiny of the characteristics of the skull itself revealed several autapomorphies that define Megalosaurus as an animal with a relatively weak bite force. Among these features are the presence of a large foramen at the back of the jaw and the theoretical positioning of an air sac at the cheek (Benson, 2010). The skull itself would be considerably lighter than that of Allosaurus, which supports the notion that Megalosaurus could exert a high mechanical advantage and had highly efficient jaws (Sakamoto, 2010). The shape of the lower jaw is most likely anteromedial, resembling Allosaurus and Giganotosaurus, as evidenced by the lack of an enlarged third tooth socket. The FEA analysis by Emily Ray Field on Allosaurus (2001) also indicated that Allosaurus possessed a weak bite.

Benson’s research also referred to Megalosaurus as being relatively muscular, indicated by the level of ossification of most of the skeleton (excluding the hind legs).

The teeth themselves have very large serrations (<8 serrations per 5 mm), which are also found on theropods like Tyrannosaurus, which are now known to have, or very likely to have, indulged in hunting behaviors. The biomechanics test using the tooth casts, however, reveals that the teardrop-shaped tooth matrix was highly inefficient for slicing through thick hide, though the serrations can theoretically be used to saw through muscle if held in a specific position. The study published by Sakamoto identified two species of megalosaur, Eustreptospondylus and Dubreuillosaurus, to have a high mechanical advantage at the tip of the jaws. However, theropods in this region were mainly known to have skulls unlikely to withstand high stress, unlike Allosaurus and Tyrannosaurus. An example of a large theropod that converged with these two species in this regard is Carcharodontosaurus.


Discussion

Since Carcharodontosaurus converges with megalosaurs in terms of biting performance, some behaviors attributed to it could possibly also be identified in Megalosaurus. Carcharodontosaurus, as demonstrated in studies such as Smith, Lamanna, Lacovara, Dodson et al. (2001), was known to engage in a predator-prey relationship with the sauropod Paralititan. Recent research by Donald M. Henderson and Robert Nicholls (2015) further substantiated Carcharodontosaurus' hunting capabilities, showcasing its ability to capture and handle juvenile sauropods weighing up to 2.5 tons, all while resisting toppling.

A noteworthy comparison can be drawn between Carcharodontosaurus and Megalosaurus in terms of their potential to hunt sauropods, particularly the juvenile members. This possibility gains credence from Megalosaurus' shorter stature and presumably more robust build, as described by Benson (2010). Unlike Carcharodontosaurus, which may have faced challenges with toppling due to its center of mass and body structure, Megalosaurus might have exhibited greater stability during such predatory encounters.

Figure 2. The above scenario depicts a proposed killing technique for Megalosaurus based on behaviors theorized for Allosaurus fragillis. Megalosaurus would first bite into a concave surface on the body, such as the folds underneath the hind legs, gripping with the tip of its jaws; it then rotates its neck to get a better grip. Lastly, using its robust build and stronger neck muscles, it opposes the prey’s struggle and the resulting inertia allows the teeth to slice deeper through the flesh. (Image credit: self)


Another crucial piece of evidence in determining if Megalosaurus would have fed on the sauropods in its ecosystem would come in the form of bite marks on the latter’s bones. The only recorded case that could be found was the end of a referred femur found close to Newport Pagnell around 2010, containing teeth marks at the broken end. There is no guarantee that these teeth marks belong to Megalosaurus or if this specimen was even brought down by hunters. Several remains of theropods from across the Great Oolite Group in Britain are all of indeterminate origin, and it has been reasoned that, in the Stonesfield Slate, more than one theropod is present alongside Cetiosaurus, only one of which is the original Megalosaurus bucklandii (Day and Barrett, 2004). So the owner of the tooth marks may remain anonymous but is still proof of a predator-prey relationship involving Cetiosaurus, and one of these predators could very well be Megalosaurus.

Allosaurus was also a crucial species in making comparisons. Bakker (1998) states that the upper skull of Allosaurus was well adapted to be slammed down onto prey items with brute force, indicated by several unique features of the Allosaurus skull, such as the rear of the skull base pointing downwards, which Megalosaurus would appear to lack (by comparing to Torvosaurus, on which the reconstructed skull is based upon); other details of the skull that would support this behavior in Megalosaurus have never been found, so this technique is likely not applicable. In 2001, Emily Rayfield had previously identified Allosaurus as having a weak bite, but simultaneously having extremely powerful head-depressing muscles, and so argued that Allosaurus could use its head like a hatchet, slamming the upper jaw down onto prey to cause massive shock.

However, these interpretations have been challenged by a more convincing theory provided by Mauricio Antón et al. in 2003, in an article that states the various flaws that would occur if Allosaurus really did use its jaws in a manner similar to a hatchet (the lower jaw would be dislocated, teeth can be easily lost, etc.). It instead offers an alternative hunting method, which would more practically involve Allosaurus aiming for a curved surface on the body of a prey item, allowing it to get a good grip, using powerful head-depressing muscles to sink the teeth first, then twisting its neck to get a more firm hold on the flesh. This is mainly useful for hunting sauropods such as Diplodocus. Discussing the ramifications of translating these techniques to Megalosaurus, its skull does not appear designed to have strong head-depressing muscles and is indeed more likely to be more useful in rotating the skull to the side. The 2010 study would also indicate that its skull was unlikely to endure high stress like Allosaurus or Tyrannosaurus. This may very well not be designed to regularly attack a large prey animal like Cetiosaurus, so it may have been more likely to target stegosaurs, which are indeed recorded in formations from the Inferior Oolite Group in which Megalosaurus is present (Galton, 2017); the article itself explicitly states that megalosaurs were more suited to hunting smaller prey than adult sauropods.



Figure 3. If one infers the biological pattern of the largest prey being preyed on by the largest predator, it can be inferred that Megalosaurus would have hunted down sauropods like Cetiosaurus and Cetiosauriscus.






The way in which Megalosaurus might have killed stegosaurs may be described like this: first, they would bite into a curved surface on a stegosaur, fast approaching to ensure the prey does not escape; they may then use powerful muscles to rotate their necks sideways. The high inertia of the stegosaur trying to escape whilst the Megalosaurus pulls back just as hard using its proposed muscular stock would allow for the teeth to slice more thoroughly through the flesh, and also to resist toppling while the prey struggles. This method of hunting would still expend a lot of energy to pull back the neck and slice the teeth further into the flesh; it may be that the very reason Megalosaurus evolved air sacs in the first place was in order to compensate for this high-energy expenditure by allowing for higher rates of respiration to release as much energy as possible for the neck muscles to pull backward.

Consideration of the brain’s shape was also key in understanding the behaviors of Megalosaurus around food. One known endocast of a brain found in Normandy, France, in the late 1990s is very likely from one of two species of megalosaur, or possibly its own species. This braincase appears to more closely resemble representatives of the allosaur family than the tyrannosaur family (Knoll, Buffetaut, and Bülow, 1999). A year before its discovery, the find of an Allosaurus endocast had shown the brain of an Allosaurus to be very similar in shape to an alligator’s (Rogers, 1998), meaning that allosaurs, and therefore, megalosaurs, would have had similar behaviors to alligators, with large olfactory bulbs for smelling out food and automatically eating anything that it sees as a food item with no hesitation. This would make Megalosaurus a more opportunistic predator, not beyond scavenging or randomly gobbling smaller animals. This type of behavior has been implied in some iconological species of megalosaur, mainly from Portugal, where tracks of several predators have been seen running parallel to each other, all directed towards an ancient shoreline (Razzolini et al., 2016); this suggests that most of these predators were purposely walking across these flats during low tide to feast on beached corpses of fish, ichthyosaurs, and turtles.


Figure 4. As likely as the Megalosaurus was to hunt mid-sized herbivores like a stegosaur (left), it was also known to scavenge carrion that may have been washed up during low tide (right). (Image credit: self)


Conclusion

To summarize, Megalosaurus would most likely be a hunter of slow-moving, medium-sized herbivores like stegosaurs; if it were to prey on sauropods, it would be more likely to target the juveniles. Killing its prey comes in two steps: first, the Megalosaurus bites into a concave surface and rotates its neck; secondly, it uses its robust build to resist the prey’s struggle, slicing its teeth deeper into the flesh, a process which still requires an air sac in order to release a lot of energy to bite firmly into the hide. When Megalosaurus is not hunting, it is a generalist scavenger, sometimes combing beaches for washed-up carcasses, meaning it could possibly feed on fish, ammonites, or marine reptiles.

There are a few other considerations that may factor into Megalosaurus’ hunting techniques, which could be explored in the future. For instance, the arms are proportionally similar to Allosaurus and extremely robust (Benson 2010), likely ending in three-fingered hands with highly-recurved claws, based on other megalosaurs; these could possibly be used to hook onto the flesh of and hold onto larger prey like sub-adult sauropods, preventing Megalosaurus from toppling over. Since the legs also do not appear as robust as the rest of the skeleton, these could possibly be better adapted to reaching higher speeds to chase down swifter-moving prey.

 

References:

  1. Brusatte, S. L. (2012). Dinosaur Paleobiology (1st ed.). John Wiley & Sons, Ltd.

  2. Anonymous. (2021). Megalosaurus, Buckland, 1842. PLAZI. http://treatment.plazi.org/id/604C1154FF98615051C4F943FD80FB96

  3. Rauhut, O. W. M. (2016). A new megalosaurid theropod dinosaur from the late Middle Jurassic (Callovian) of north-western Germany: Implications for theropod evolution and faunal turnover in the Jurassic. Palaeontologia Electronica, 19(2), 1-65. https://www.researchgate.net/publication/308297143_A_new_megalosaurid_theropod_dinosaur_from_the_late_Middle_Jurassic_Callovian_of_northwestern_Germany_Implications_for_theropod_evolution_and_faunal_turnover_in_the_Jurassic

  4. Upchurch, P. (2003). The anatomy and taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England. Journal of Vertebrate Paleontology, 23(1), 208-231. https://www.researchgate.net/publication/349408406_The_anatomy_and_taxonomy_of_Cetiosaurus_Saurischia_Sauropoda_from_the_Middle_Jurassic_of_England

  5. Benson, R. B. J., et al. (2008). The taxonomic status of Megalosaurus bucklandii (Dinosauria, Theropoda) from the Middle Jurassic. Paleontology, 51(Part 2), 421-423. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1475-4983.2008.00751.x

  6. Benson, R. B. J. (2008). A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods. Zoological Journal of the Linnean Society, 886-890. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1096-3642.2009.00569.x

  7. Mateus, O., & Hendrikx, C. (2014). Torvosaurus gurneyi n. sp., the largest terrestrial predator from Europe, and a proposed terminology of the maxilla anatomy in nonavian theropods. PLoS ONE, 9(3). https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0088905#s4

  8. Sakamoto, M. (2010). Jaw biomechanics and the evolution of biting performance in theropod dinosaurs. Proceedings of the Royal Society B: Biological Sciences, 3329-3331. https://royalsocietypublishing.org/doi/10.1098/rspb.2010.0794

  9. Chin, K., & Bishop, J. R. (2007). Exploited Twice: Bored Bone in a Theropod Coprolite from the Jurassic Morrison Formation of Utah, U.S.A. SEPM Special Publications, 88, 379-387. https://www.researchgate.net/publication/285294846_Exploited_TwiceBored_Bone_in_a_Theropod_Coprolite_from_the_Jurassic_Morrison_Formation_of_Utah_USA

  10. Pahl, C. C., & Ruedas, L. A. (2021). Carnosaurs as Apex Scavengers: Agent-based simulations reveal possible vulture analogs in late Jurassic Dinosaurs. Ecological Modelling, Volume 458. https://www.sciencedirect.com/science/article/abs/pii/S0304380021002611?dgcid=coauthor

  11. Antón, M., et al. (2003). The muscle-powered bite of Allosaurus (Dinosauria; Theropoda): An interpretation of cranio-dental morphology. Estudios Geology, 59, 313-323. https://pdfs.semanticscholar.org/ff86/d6bc7f019240ba995159e01b36baae069111.pdf

  12. Razzolini, N. L., et al. (2016). Ichnological evidence of megalosaurid dinosaurs crossing Middle Jurassic tidal flats. Scientific Reports, 6, Article number: 31494. https://doi.org/10.1038/srep31494

  13. Cleal, C. J., & Rees, P. M. (2003). The Middle Jurassic Flora from Stonesfield, Oxfordshire, UK. Paleontology, 46(4), 739-801. https://www.researchgate.net/publication/230448134_The_Middle_Jurassic_Flora_from_Stonesfield_Oxfordshire_UK

  14. Galton, P. (2017). Purported earliest bones of a plated dinosaur (Ornithischia: Stegosauria): A "dermal tail spine" and a centrum from the Aalenian-Bajocian (Middle Jurassic) of England, with comments on other early thyreophorans. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 285(1), 6-7. https://www.researchgate.net/publication/318425542_Purported_earliest_bones_of_a_plated_dinosaur_Ornithischia_Stegosauria_A_dermal_tail_spine_and_a_centrum_from_the_Aalenian_Bajocian_Middle_Jurassic_of_England_with_comments_on_other_early_thyreophorans

  15. Smith, J. B., et al. (2001). A Giant Sauropod Dinosaur from an Upper Cretaceous Mangrove Deposit in Egypt. Science, 292(5522), 1704-1706. https://www.researchgate.net/publication/11952657_A_Giant_Sauropod_Dinosaur_from_an_Upper_Cretaceous_Mangrove_Deposit_in_Egypt

  16. Henderson, D. M., & Nicholls, R. (2015). Balance and strength - estimating the maximum prey lifting potential of the large predatory dinosaur Carcharodontosaurus saharicus. The Anatomical Record, 298(8), 1367–1375. https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.23164

  17. Knoll, F., & Buffetaut, E. (1999). A theropod braincase from the Jurassic of the Vaches Noires cliffs (Normandy, France). Bulletin de la Societe Geologique de France, 170(1), 103-109. https://www.researchgate.net/publication/266740755_A_theropod_braincase_from_the




33 views0 comments

Recent Posts

See All

Commentaires


bottom of page