Functional Morphology of Animal Feeding Apparata

[theropod]

From what I read they suggest it did this by inertial feeding (shaking). It is debatable whether I would call this slicing. snively et al., 2013 also stated the tearing action was more notable in Allosaurs, rather comparing tyrannosaurs to crocodilians. EDIT: and Studies considering tooth morphology found Tyrannosaur teeth to be ineffective slicing tools.
The neck muscles also seem to show a clear function of controlling prey with the mouth (Snively & Russel suggest, they lacked the functional forelimbs other theropods would have used)

Overall, tyrannosaurs unsurprisingly seem to have complemented their broader, blunter teeth by using raw power while feeding, the same is seen in crocodilians, used as an analogy by the authors (of course those lack cutting edges and hence are no ideal analogy, but the difference should be clear).

Thanks for posting!

[creature386]

I don't think crocodiles are a good comparison. Tyrant has compared their teeth on CF and the ones of Tyrannosaurus were sharper than the ones of crocodiles.
Coherenstsheaf also said that the crushing of crocodiles and Tyrannosaurus may have been a bit different:
carnivoraforum.com/single/?p=8408855&t=9755970

[theropod]

"(of course those lack cutting edges and hence are no ideal analogy, but the difference should be clear)"
That's what I wrote.

Their teeth are not the same. They are just an analogy for the feeding style, requiring a lot of strenght.

The crushing of T. rex seems base on long teeth, going deep and effectively breaking bones without additional help. In crocodilians, the teeth are rather for gripping and most of the damage is done by deathrolls or shaking, or simply drowning.
While feading, logically T. rex rather relies on raw power to tear pieces off its prey, contrary to animals with primarily slicing jaws.

[creature386]

There are several additional lines of evidence, gleaned from our monographic redescription, that support this conclusion. First is the sophisticated occlusal pattern, as Dakosaurus (D. maximus and D. andiniensis) had tightly-packed interlocking teeth which created a precise tooth-to-tooth occlusion (see Fig. 1) [17]. Second, biomechanical modelling has shown that oreinirostral snouts (like that of Dakosaurus) are more resistant to both torsional and bending stresses than a platyrostral or tubular snout [106]–[108]. Third, biomechanical modelling also confirms that, in other archosaur taxa, ‘lateral plates’ like those of Dakosaurus occur on dentigerous bones that experience high localised stress thereby helping to dissipate feeding-induced stresses acting on the bases of adjacent teeth [85]. Fourth, Dakosaurus is the only known metriorhynchid to exhibit macroziphodonty [2], [11], [20], and denticulated teeth are known to be efficient at slicing and cutting because they require less energy to penetrate food, thereby making larger and tougher organisms more energetically feasible prey items [11], [109], [110]. Finally, the high incidence of enamel spalling and crown apex breakage in D. maximus (Fig. 8) [17] is interesting when compared to recent work on the killer whale, which suggests that high incidences of crown breakage/apical wear may be due to a diet rich in abrasive-skinned chondrichthyans or a generalist diet of predominately suction-feeding whole fish [87], [88]. Differences in how ‘extreme’ tooth wear is between Dakosaurus maximus and killer whales can be explained through tooth replacement. Archosaurs, like Dakosaurus, have continual tooth replacement whereas odontocetes, like killer whales, are monophylodont (single set of teeth) [111].

Source: Young MT, Brusatte SL, de Andrade MB, Desojo JB, Beatty BL, et al. (2012) The Cranial Osteology and Feeding Ecology of the Metriorhynchid Crocodylomorph Genera Dakosaurus and Plesiosuchus from the Late Jurassic of Europe. In: PLoS ONE 7(9): e44985. p. 1-42 doi:10.1371/journal.pone.0044985

[theropod]

On the myth of slicers*, be it dinosaurs, lizards or sharks, avoiding bony regions at all costs:

Clearly, theropods could also drag their
teeth across bones without sustaining injury or dam-
age to the teeth and this could be done repeatedly to
weaken or damage bones (e.g. as with the Camarasau-
rus ilium, see Chure et al. 2000).[...]
Smaller bones (e.g. distal caudal vertebrae and pha-
langes) could probably have been swallowed whole by
many theropods. Some medium-sized bones (e.g. ver-
tebrae and ribs) could be bitten through or at least
have parts removed relatively easily (e.g. neural
arches) by large theropods. Even those genera that do
not appear to be well adapted to biting on bone could
probably have broken a neural spine that was only a
few millimetres thick.
It has been suggested that the feeding strategy of
theropods involved careful avoidance of any tooth–
bone contact (Chure et al. 2000) and may have been
aimed at avoiding damage to the teeth. Teeth in most
theropods probably represented important tools for
prey capture as well as feeding, and thus significant
damage or loss might have severely impeded their
survival. While this may well have been true for small
theropods with fine, fragile teeth (e.g. dromaeosaurids)
and these could also be more delicate in their
feeding on larger bones, it seems doubtful for the
larger carnivores. Even so, there are scrape marks and
even a tooth embedded in bone attributable to
dromaeosaurid predators (Currie & Jacobsen 1995)
showing that even these animals produced strong
tooth–bone contacts and even broke teeth during
feeding.
The ‘carnosaurs’ with relatively thin teeth (e.g. car-
charodontosaurids) might have risked damage to their
teeth if they impacted on bone, and the slightly curved
or sinusoidal shape of their crowns (see Fig. 2) leaves
them vulnerable to bending forces during heavy com-
pressive pressure compared with a straight tooth.
However, these teeth were still relatively robust (com-
pared with those of smaller theropods, in addition to
being absolutely more robust), and although not mo-
lariform, they are much bigger in absolute size than
the teeth of many mammals capable of bone-cracking
behaviour. Thus, the risk is unlikely to be as high as
might otherwise be inferred compared with mammals
capable of cracking large bones. Furthermore, biting
in these animals was probably strictly orthal, in which
case the bite force is transmitted directly from the tip
of the tooth to the base, so that the lateral flattening of
the tooth plays only a minor role. Indeed, biomechan-
ical studies have shown both the ability of theropod
skulls (Rayfield et al. 2001; Rayfield 2005) and teeth
(Mazzetta et al. 2004) to withstand large bite forces.
In addition, the constant replacement of teeth in
theropods means that there is overall relatively little
harm to an individual in losing or breaking a few teeth
if this leads to gaining a vital meal. Even modern and
recently extinct mammals that cannot replace teeth
can show high incidences of broken canines and carn-
assials (van Valkenburgh 1988, 2009) that would pre-
sumably have more serious consequences for them
than for a theropod that could replace its damaged
teeth.
At least some large non-tyrannosaur theropods
were capable of exerting bone-crunching bites on
bones (presumably without tooth damage) as
observed by the bitten-through Allosaurus pubic boot
and Stegosaurus armour plate (see Table 1). There are
also records of theropods inflicting significant damage
on conspecifics through cranio-facial biting behav-
iours in both tyrannosaurids and allosauroids (Tanke
& Currie 2000). Clearly, theropods were willing to
engage in behaviour that risked damage to their own
teeth, jaws and skull in circumstances that would pre-
sumably involve more risk than static feeding on a
corpse.

Hone, D.W.E. & Rauhut, O.W.M. 2009: Feeding behaviour and bone utilization by
theropod dinosaurs.
Lethaia, 10.1111/j.1502-3931.2009.00187.x
www.bio.utk.edu/biologyinbox/unit1/readings/Hone%20&%20Rauhut%202009%20-%20Feeding%20behaviour%20and%20bone%20utilization%20by%20theropod%20dinosaurs.pdf

As a little demonstration, the ilium of a Camarasaurus from the Morrison Formation, bearing bite marks supposedly made by the premaxillary teeth of a theropod, supposedly Allosaurus (likely going by its abundance). Note such bite marks are not very common, not even in Tyrannosaurs, but Camarasaurus was not only supposedly much larger than the animal that left the bite marks, but the ilium is also among the largest and most robust bones in a dinosaur skeleton.


*Hereby defined as animals with comparatively thin, "delicate" teeth relying primarily on soft-tissue evisceration and comparatively low bite forces

[creature386]

Consideration of the functional anatomy of spinosaurs in a further study using second moments of area and moments of inertia attempted to understand theropod feeding[39]. Based on the dentary results, similarities to Orinoco crocodiles (Crocodylus intermedius), and length of the mandibular symphysis, the authors concluded that the spinosaurs probably fed on smaller prey, capturing them in their rosette of teeth and holding the prey or shaking their heads dorsoventrally, because their skulls were not very resistant to mediolateral bending [39], [55]. Here we find the same trend in the rostrum: the values obtained for Suchomimus dentaries in this previous study [39] are very similar to those calculated for the rostra of the spinosaurs in this study. Spinosaurs possess deep rooted teeth and near vertical-sided teeth rows, ideal for resisting large dorsoventrally orientated biting forces and dissipation of forces through the skull [55]. Calculations of bite force in Suchomimus [39] suggest that the bite may have been comparable to an alligator with a mandibular length of 50 cm suggesting that spinosaurs were capable of capturing terrestrial prey [39].

Cuff AR, Rayfield EJ (2013) Feeding Mechanics in Spinosaurid Theropods and Extant Crocodilians. PLoS ONE 8(5): e65295. doi:10.1371/journal.pone.0065295

[creature386]

The "cracking teeth" debate is long over, but I have to quote an old post, because I made an error:

May 25, 2013 1:55:13 GMT 5 creature386 said:

Theropod, it seems like Grey's opinion isn't very different from yours, because the quote of Kent says pretty much the same as you say:

The slenderness ratio is a measure of length to breadth. Needle-like teeth with high slenderness ratios are good for grasping small prey, like mackerel or flounder, but buckle under loads applied along their length, as would happen if an animal munched on the bone of a large sea mammal. Mechanical advantage relates the length of a tooth to the length of its root. Long teeth with short roots have low mechanical advantage and are more easily pulled from the jaw than teeth with comparatively larger roots.

The teeth of great whites have the high bending strength ratios of cutting teeth, high slenderness ratios, implying they are not designed for crushing, and roots that are short when compared with the overall tooth height. This means a great white's teeth have a low mechanical advantage and will likely be ripped out by struggling prey. Such a combination of parameters, says Kent, "is ideal for a shark that hunts with a slash-and-release type of attack that concentrates on the softer portions of the prey". Surveys of the corpses of marine mammals killed by great whites confirm that, when feeding on sea lions, small whales and porpoises, the sharks most frequently attack the delicate abdomens or rear flippers of their victims. Though they often tear off chunks of flesh during an attack, the sharks rarely grapple with large prey, waiting instead for the animal to die of injuries, or carrying animals in their jaws until they bleed to death, before feeding at their leisure.

Megalodon teeth, though superficially similar to those of great whites, have an entirely different set of parameters. Though they share the serrated cutting edge, megalodon teeth are comparatively thicker for their size with much lower slenderness and bending strength ratios. They also have roots that are substantially larger relative to total tooth heights, and so have a greater mechanical advantage.

Kent explains that teeth with these traits not only make good cutting tools, but are also well suited to grasping powerful prey and unlikely to crack when they bite down on bone. The differences between the teeth of great white and megalodon suggest fundamental differences in their diet, attack behaviour, or indeed both. But Kent reasons that as large mammals formed the menu of both sharks, the difference in their teeth must be related to variations in their attack behaviour.

Source: issue 2190 of New Scientist magazine, 12 June 1999, page 32
Maybe he ment being ripped out by saying "being cracked".

I admit I should have read "Hell's teeth" more carefully, before using it as a source:

Kent explains that teeth with these traits not only make good cutting tools, but are also well suited to grasping powerful prey and unlikely to crack when they bite down on bone. The differences between the teeth of great white and megalodon suggest fundamental differences in their diet, attack behaviour, or indeed both. But Kent reasons that as large mammals formed the menu of both sharks, the difference in their teeth must be related to variations in their attack behaviour.

The cracking issue was indeed mentioned in the article.

[theropod]

Unlikely in this regard means "less likely than in Carcharodon", just to clarify that.
It is the reference point it is nearly always compared to, instead of comparing it to a wider variaty of animals. Some functional analysis of large predator teeth would be really nice, too many myths and loose interpretations are floating around, including that some equate Carcharocles with T. rex as regards their tooth function...

[creature386]

I didn't want to say that I necessarily support Grey's view, I simply wanted to point out my mistake.

[creature386]

I am now posting something about Lycaenops' feeding apparatus. It is very hard to find reliable information on the feeding apparata of gorgonopsids in the web, therefore this may be interesting:

Evidently the dentition in Lycaenops was a biting, slashing mechanism. Animals of this genus, and most of the other specialized gorgonopsians aswell, probably were very active hunters, seizing and killing their prey with the sharp incisors and the long, saber-like canines. There must have been very litle chewing of the food; rather it it was probably torn into large pieces and swallowed whole.

Colbert, e. H. (1948): The mammal-like reptile Lycaenops. – Bull. Am. Mus. Nat. Hist., 89: 357-404.
Here the PDF download link:

digitallibrary.amnh.org/dspace/bitstream/handle/2246/401//v2/dspace/ingest/pdfSource/bul/B089a06.pdf?sequence=1

The paper also said that it had serrated canine teeth.

Here you can see a detailed description of the skull, where they say that Lycaenops had an elongated, narrow and deep skull (a slicer skull):
tobias-lib.uni-tuebingen.de/volltexte/2007/2935/pdf/Eva_Gebauer.pdf

[theropod]

Jul 3, 2013 5:23:54 GMT 5 Grey said:

Scientists have analysed how an extinct sabretooth animal with huge canines dispatched its prey, finding that strong neck muscles were vital for securing a kill.

The marsupial, which terrorised South America 3.5 million years ago, had the biggest canine teeth for its size.

Experts say the big beast possessed extreme adaptations to the "sabretooth lifestyle".

The killing behaviour of Thylacosmilus atrox, is described in Plos One.

Until now, the extinct sabretooth "tiger" Smilodon fatalis has received most attention as a ferocious sabretooth predator.

But millions of years earlier, a pouched marsupial was one of dozens of sabretooth beasts that had roamed the Earth before the better known killer Smilodon, which went extinct at the end of the last Ice Age.

Like Smilodon, Thylacosmilus had highly specialised canines adapted to kill large beasts but until now little was known about the exact way it killed its prey.

Scientists took CT scans of fossil remains to construct high-resolution digital 3D models of both sabretooth beasts, and compared them to the modern leopard.

The simulations were digitally loaded with forces to see how the animals would have behaved when biting and killing prey.

Weak bite

The work was led by Stephen Wroe from the University of New South Wales, Australia, who explained that Thylacosmilus's closest living relatives are Australian and American marsupials.

"We found that both sabretooth species were similar in possessing weak jaw muscle driven bites compared to the leopard, but the mechanical performance of the sabretooths' skulls showed that they were both well-adapted to resist forces generated from very powerful neck muscles," said Dr Wroe, who led the research.

For its size - Thylacosmilus's huge canine teeth were larger than those of any other known sabretooth. The roots of these canines went back to within millimetres of its very small brain case.

"Thylacosmilus was even more extreme. Its skull easily outperformed that of the placental Smilodon and was much better adapted to resist forces incurred by a neck-driven bite."

This adaptation was vital as its long thin canines were vulnerable to snapping. To hunt, the animal had to secure and immobilise large prey using its powerful forearms before inserting its long canines into the windpipe or major arteries of the neck - "a mix of brute force and delicate precision".

Fragile teeth

These adaptations allowed for a relatively rapid kill of dangerous big prey. "The bottom line is that the huge sabres of Thylacosmilus were driven home by the neck muscles alone - and - because the teeth were actually quite fragile - this must have been achieved with surprising precision.

"It may not have been the smartest of mammalian super-predators - but in terms of specialisation - Thylacosmilus took the already extreme sabretooth lifestyle to a whole new level, which clearly exceeded that of the much better known sabretooth tiger."


Source : www.bbc.co.uk/news/science-environment-23126270

Plos One paper : www.plosone.org/article/info:doi/10.1371/journal.pone.0066888

When will people learn it? ;D

That reminds me, what creature posted above about Lycaenops suggests a slashing bite for it, and it too has sabre teeth. Seems to go in the same direction.

[creature386]

The canines of Hyaenodon are mediolaterally compressed and like those in canids and not like the rounded canines in felids. This type of canines is ideal for slashing. Thus, Hyaenodon inflicted its prey with shallow wounds and not with a killing bite like recent felids do (additional evidence comes from the non-specialized whiskers). The predation style of Hyaenodon was ambushing, although it did not succumb in a chase with most contemporaneous prey animals. It was a powerful predator in the forests of the Eocene as well as in the more open landscape of the Oligocene.

othes.univie.ac.at/18838/1/2012-01-20_0400967.pdf

[creature386]

The feeding apparatus of Ocepechelon, a bony pipette-like snout, is unique among tetrapods. This new taxon exemplifies the successful systematic and ecological diversification of chelonioid turtles during the Late Cretaceous. This new evidence for a unique trophic specialization in turtles, along with the abundant marine vertebrate faunas associated to Ocepechelon in the Late Maastrichtian phosphatic beds of Morocco, further supports the hypothesis that marine life was, at least locally, very diversified just prior to the Cretaceous/Palaeogene (K/Pg) biotic crisis.

Bardet N, Jalil N-E, de Lapparent de Broin F, Germain D, Lambert O, et al. (2013) A Giant Chelonioid Turtle from the Late Cretaceous of Morocco with a Suction Feeding Apparatus Unique among Tetrapods. In: PLoS ONE 8(7): e63586. doi:10.1371/journal.pone.0063586

[theropod]

By combining evidence from descriptive anatomical work, physical
modelling, mathematical approaches and new technologies, palaeon-
tologists are able to gain a more comprehensive knowledge of
dinosaur feeding behaviour, which, in turn, improves our under-
standing of Mesozoic ecology.
Here, we demonstrate how this approach can be used to investigate the palaeobiology of
Tyrannosaurus rex, whose gargantuan size and specialized anatomy have
made it a favourite of functional morphologists.
Comparisons of the craniodental morphology of
T. rex (Figure Ia) to living animals indicate that this animal was a carnivore. Wear facets on
the teeth show that tyrannosaurids practiced repeated shearing
between upper and lower dentitions [44](Figure Ib), offering a processing mechanism for flesh and bone. Puncture-like bite marks
on a Triceratops pelvis [15](Figure Ic) and extensive damage to the tail
of one specimen of the duck-billed dinosaur
Edmontosaurus [62] demonstrate the ability of
T. rex to penetrate bone. Two types of
repetitive biting behaviour are observed: deep puncture of thinner
cortical bone and, in deeper cortical bone, shallow puncture followed
by pulling of the teeth across the bone surface
[15]. Comparison of the cutting ability of fossilised teeth to that of varied replica blades
demonstrated that stout tyrannosaurid teeth (Figure I
d) functioned as pegs with poor cutting ability. Instead, the teeth were used to ‘grip-and-rip’ prey – the ‘puncture–pull’ feeding hypothesis[17,18]. Space-frame analysis suggests that the T. rex skull was constructed to resist strong, vertically directed bite forces [25]. FEA provides information on stress–strain patterns within the skull, and confirms that the
T. rex cranium could withstanding large feeding-induced puncture-pull loads [34](Figure I e). Furthermore, FEA studies suggest that
tyrannosaurid nasal bones were fused and thickened to withstand
large compressive and shear stresses, and that open skull sutures
assisted in ‘shock-absorption’ during powerful bites [34].
Replica teeth driven into bovine bone (mimicking the morphology of
the bitten Triceratops pelvis) indicate that T. rex could produce bite forces exceeding 6410 Newtons
[16], well in excess of those estimated
for modern lions, showing that a
T. rex bite could shatter bone
[16]. This hypothesis is confirmed by the discovery of a
T. rex coprolite [65](Figure If) that contains large quantities of pulverized bone pertaining
to an ornithischian dinosaur. In this instance, the bone of the prey
animal was only partially digested, indicating that gut-residence time
was short

faculty.cns.uni.edu/~spradlin/SandE/Readings/dinos%20PAL_E2427.pdf
Resumed evidence for bone puncturing, shattering and osteophagy in Tyrannosaurus, analysis of the purpose of its teeth and the "shock-absorber".

Another thing (which I found in The Dinosauria): Tyrannosaur teeth and serrations were functionally comparable to "a dull, smooth blade" (?probably an adaption for edge durability), not other serrated teeth like those of C. carcharias (Abler, 1992/2001; I didn't attempt to search through the hundreds of pages of references but I can look for the name of the paper if someone is interested). A comparison with some other ziphodont taxa would be interesting, particularly between more or less robust ones, since this should help asessing the purpose of the teeth.

[creature386]

Further explanation on the "puncture-pull" strategy I have found:

www.tandfonline.com/doi/abs/10.1080/02724634.1996.10011297