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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsProbably—but not human-like lips. The strongest current reconstruction gives Tyrannosaurus rex scaly, lizard-like tissue that covered its teeth when the mouth was closed. That conclusion comes from tooth wear, dental histology, tooth-to-skull proportions and comparisons with living reptiles. No fossil has preserved a T. rex lip, so the exact shape, texture and movement remain inferred rather than directly observed.
What is the best answer to “Did T. rex have lips?”
The best-supported current answer is that T. rex probably had extraoral tissue around its mouth. When the jaws were shut, that tissue would have covered most or all of the tooth crowns instead of leaving the teeth permanently exposed. In everyday language, people call this “lips,” but the proposed structure was not comparable to the flexible, muscular lips of a human.
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This interpretation comes chiefly from a 2023 study led by Thomas Cullen and colleagues. The researchers examined fossil teeth and skull anatomy, then compared those findings with living reptiles. Their conclusion was probabilistic: the evidence supports covered teeth, but it does not amount to a fossilized lip or a direct snapshot of T. rex facial tissue.
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Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →A crocodile-like reconstruction remains a serious alternative. In that view, tyrannosaurs had exposed teeth and facial tissues more like those of crocodilians. The disagreement is therefore about how to interpret indirect anatomical evidence, not about two groups finding different fossil lips.
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What the 2023 study actually examined
Tooth wear as a test of exposure
Teeth that sit outside protective mouth tissue are exposed to air, moisture changes, abrasion and contact with the environment. Teeth covered by facial tissue should experience a different pattern of wear. Cullen’s team compared a tooth from Daspletosaurus, a close tyrannosaur relative, with teeth from modern lizards and crocodilians.
The Royal BC Museum’s account of the work reports substantially more wear on the exposed portions of alligator teeth than on the Daspletosaurus tooth. That contrast is consistent with a covering that shielded the tyrannosaur tooth surface when the jaws were closed. It is not a direct measurement of T. rex lips, because the comparison uses a relative and living animals rather than preserved T. rex facial tissue.
Tooth wear is also affected by diet, tooth replacement, bite mechanics and the conditions in which a tooth was used. For that reason, the result works as one part of a cumulative case. It does not establish a precise lip outline by itself.
Dental histology
Dental histology examines the microscopic structure of tooth tissues. The study abstract says that histological evidence from crocodilians and theropods, including T. rex, supports the likelihood that their marginal teeth were covered by extraoral tissue while the mouth was closed.
Histology matters because a tooth records aspects of how it developed and functioned even when surrounding skin and muscle have disappeared. The researchers used those internal characteristics alongside wear observations rather than treating any single microscopic feature as decisive. Histology therefore strengthens the covered-tooth interpretation without turning an inference into direct soft-tissue preservation.
Tooth size and skull proportions
One traditional objection to theropod lips is that their teeth appear too large to fit beneath facial tissue. Cullen and colleagues tested that idea by comparing skull length and tooth size across theropods and living monitor lizards. They concluded that theropod teeth were not unusually large relative to the skull and could plausibly have fitted beneath a soft-tissue covering.
Thomas Cullen, quoted by the Natural History Museum, summarized the point this way: “Although it’s been argued in the past that the teeth of predatory dinosaurs might be too big to be covered by lips, our study shows that their teeth were not atypically large.” The comparison addresses physical plausibility. It does not show exactly where the tissue began or how far it extended across the jaws.
Why monitor lizards are useful analogues
Living monitor lizards provide a relevant anatomical comparison because many have substantial, scaly tissue around the mouth and teeth that are not continuously exposed when the jaws are closed. Their skull-tooth proportions and facial arrangement give researchers a living model for testing whether a large predatory reptile could protect its teeth with external tissue.
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The analogy has limits. A monitor lizard is not a miniature tyrannosaur, and similar proportions do not prove identical soft-tissue anatomy. Researchers use the animals to constrain what is mechanically and biologically plausible, then combine that comparison with fossil evidence from theropods.
What “lips” means in a T. rex reconstruction
In this debate, “lips” is shorthand for scaly or lizard-like extraoral tissue around the mouth. The tissue would have covered the teeth when the jaws were closed, somewhat as facial scales cover the teeth of many living reptiles.
That wording should not suggest mammal-like expressions, a movable upper lip, or the ability to curl the mouth into a snarl. The Royal BC Museum specifically distinguishes the proposed tissue from muscular, mobile human lips. A reconstruction could show a closed mouth with only the outer facial scales visible while still allowing the animal to open its jaws widely for feeding.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchThe evidence also does not determine whether the tissue was smooth or heavily scaled, how much it overlapped the lower jaw, or how it moved during biting. Illustrations that give T. rex a sharply outlined lip line are visual hypotheses built on the broader covered-tooth model.
Why fossils cannot simply show the answer
Bone normally fossilizes more readily than skin, muscle and other facial tissues. The Natural History Museum notes that soft tissue is preserved only in rare circumstances. Tyrannosaur fossils therefore preserve the jaw framework and teeth far more often than they preserve the structures that once surrounded them.
Scientists must infer appearance from several kinds of evidence:
- Surface anatomy: textures, ridges and openings on jaw bones can indicate where blood vessels, muscles or connective tissues were attached.
- Functional traces: wear and damage on teeth can reveal whether the crowns were repeatedly exposed or protected.
- Internal structure: histology can record how teeth formed and operated.
- Comparative anatomy: living reptiles demonstrate which arrangements remain workable in a similar body plan.
- Proportions: skull and tooth dimensions can test whether a proposed covering could physically fit.
These lines of evidence constrain a reconstruction, but none supplies a complete image of the original face. A fossil can show that a proposed arrangement is plausible or difficult; it rarely shows the exact outline of tissue that decayed millions of years ago.
Why some researchers still reconstruct exposed teeth
The competing interpretation draws on the texture of tyrannosaur jaw bones and comparisons with crocodilian facial anatomy. Crocodilians have exposed teeth and facial tissues that differ from those of monitor lizards. Researchers who favor that model argue that tyrannosaur bone surfaces may fit a crocodile-like face better than a lizard-like one.
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Thomas Carr, a palaeontologist at Carthage College associated with the earlier crocodile-like reconstruction, criticized the 2023 study. Science News quoted his description of the lips interpretation as “completely unconvincing.” His objection concerns the anatomical reading of the evidence; it is not evidence that preserved T. rex lips have been found.
The disagreement illustrates an important limitation of palaeontological reconstruction. The same skull can support more than one soft-tissue model when the decisive tissues are absent. Bone texture is informative, but its meaning depends on comparisons with living animals and on assumptions about how tissues attach and function.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Covered teeth and exposed teeth compared
| Question | Covered-tooth reconstruction | Crocodile-like reconstruction |
|---|---|---|
| Would closed-mouth teeth be externally visible? | Extraoral tissue would cover the marginal teeth when the mouth was closed. | Teeth would remain externally exposed, as in a crocodilian-style face. |
| How is tooth wear interpreted? | The relatively low wear reported for a Daspletosaurus tooth, compared with exposed alligator teeth, is consistent with protection. | The tooth-wear comparison is not accepted as sufficient to overturn an exposed-tooth model. |
| How is dental histology used? | Histology from crocodylians and theropods, including T. rex, supports coverage by extraoral tissue. | The interpretation remains disputed because histology does not preserve the surrounding facial tissue itself. |
| Which facial comparisons are emphasized? | Living monitor lizards provide examples of scaly tissue covering teeth. | Crocodilian facial anatomy and tyrannosaur jaw-bone texture are emphasized. |
| How certain is the appearance? | Probable as a functional reconstruction, with the exact shape and movement unknown. | Possible alternative; it remains an interpretation of indirect evidence. |
What the evidence supports—and what it does not
Supported by the current case
- T. rex teeth were not demonstrably too large to fit beneath facial tissue.
- Comparative tooth wear is consistent with a protective covering.
- Dental histology supports extraoral coverage of marginal teeth.
- Living monitor lizards show that a large predatory reptile can have scaly tissue around covered teeth.
- A closed-mouth T. rex reconstruction with covered teeth is therefore scientifically plausible and, on the 2023 study’s reading, probably more likely.
Not established by the fossils
- No specimen has preserved T. rex lips or a complete facial skin outline.
- The fossils do not reveal whether the tissue was thick, thin, smooth, or prominently scaled.
- They do not show whether the tissue moved during breathing, feeding or display.
- They do not prove that every tyrannosaur species had exactly the same facial covering.
- They do not eliminate the crocodile-like interpretation.
Keeping those boundaries clear prevents a common mistake: treating a plausible reconstruction as if it were a photograph. The study examined fossil teeth and anatomy, not preserved lips.
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How the debate could be resolved
New evidence would need to preserve or more narrowly constrain facial tissue. Rare exceptional fossils with skin impressions, connective-tissue traces or unusually detailed jaw surfaces could help. Better samples of tyrannosaur teeth could also test whether the wear pattern reported for Daspletosaurus is consistent across individuals and species.
Future work may also refine comparisons with living reptiles. The most useful studies would examine several monitor lizard and crocodilian species, measure how their facial tissues relate to tooth wear and jaw-bone texture, and then test those relationships against a larger tyrannosaur fossil sample. Such results could shift the balance without producing a perfectly preserved T. rex face.
How to read new claims about T. rex lips
- Check what was actually preserved. A claim based on teeth and bone is an inference, not a fossilized lip.
- Separate anatomy from artwork. A detailed illustration may show one proposed shape, not a measured outline.
- Ask which living animals were used for comparison. Monitor lizards and crocodilians provide different facial models.
- Look for multiple evidence lines. Wear, histology, proportions and bone texture answer different parts of the question.
- Watch the confidence language. “Probably,” “supports” and “inferred” accurately describe the current state of the evidence; “proven” does not.
The most defensible picture today is a T. rex with scaly facial tissue that likely concealed its teeth at rest, while acknowledging that a crocodile-like, exposed-tooth face remains scientifically argued. The fossils narrow the possibilities; they do not preserve enough soft tissue to settle the exact appearance.
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