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. 2019 Mar 4;7:e6573.
doi: 10.7717/peerj.6573. eCollection 2019.

Feeding Traces Attributable to Juvenile Tyrannosaurus rex Offer Insight Into Ontogenetic Dietary Trends

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Free PMC article

Feeding Traces Attributable to Juvenile Tyrannosaurus rex Offer Insight Into Ontogenetic Dietary Trends

Joseph E Peterson et al. PeerJ. .
Free PMC article

Abstract

Theropod dinosaur feeding traces and tooth marks yield paleobiological and paleoecological implications for social interactions, feeding behaviors, and direct evidence of cannibalism and attempted predation. However, ascertaining the taxonomic origin of a tooth mark is largely dependent on both the known regional biostratigraphy and the ontogenetic stage of the taxon. Currently, most recorded theropod feeding traces and bite marks are attributed to adult theropods, whereas juvenile and subadult tooth marks have been rarely reported in the literature. Here we describe feeding traces attributable to a late-stage juvenile Tyrannosaurus rex on a caudal vertebra of a hadrosaurid dinosaur. The dimensions and spacing of the traces were compared to the dentition of Tyrannosaurus rex maxillae and dentaries of different ontogenetic stages. These comparisons reveal that the tooth marks present on the vertebra closely match the maxillary teeth of a late-stage juvenile Tyrannosaurus rex specimen histologically determined to be 11-12 years of age. These results demonstrate that late-stage juvenile and subadult tyrannosaurs were already utilizing the same large-bodied food sources as adults despite lacking the bone-crushing abilities of adults. Further identification of tyrannosaur feeding traces coupled with experimental studies of the biomechanics of tyrannosaur bite forces from younger ontogenetic stages may reveal dynamic dietary trends and ecological roles of Tyrannosaurus rex throughout ontogeny.

Keywords: Feeding trace; Ontogeny; Paleoecology; Tyrannosaur.

Conflict of interest statement

The authors declare there are no competing interests.

Figures

Figure 1
Figure 1. Discovery location of BMR P2007.4.1.
Locality map showing the geographic location of specimen BMR P2007.4.1 in Carter County, Montana.
Figure 2
Figure 2. Stratigraphic column of the “Constantine” Quarry.
Stratigraphy of the BMR P2007.4.1 “Constantine” Quarry.
Figure 3
Figure 3. Map of the BMR P2007.4.1 “Constantine” Quarry.
Dorsal vertebrae (field numbers CON-2007-010, CON-2007-011, and CON-2007-012) were too weathered for collection, though their relative locations were mapped. Note the relative association of dorsal and caudal vertebrae, and pelvic elements.
Figure 4
Figure 4. Punctured caudal vertebra of BMR P2007.4.1.
BMR P2007.4.1 in anterior (A) posterior (B) and ventral (C), including the two elliptical punctures on the ventral surface of the centrum (D, E).
Figure 5
Figure 5. Silicone peel produced from BMR P2007.4.1.
Silicone peel produced from the ventral surface of the punctured caudal vertebra of BMR P2007.4.1 in vertical (A), and lateral (B) views. Note the traced outlines demonstrating the shape of the tooth casts.
Figure 6
Figure 6. Casts of BMR P2002.4.1 maxilla (A) and dentary (B) to illustrate the tooth positions used for spacing measurements.
Note the alternating replacement of teeth. Scale bars equal 10 cm.
Figure 7
Figure 7. Maxillary and dentary measurements for BMRP 2002.4.1 and BHI 3033 mesiodistal and labiolingual dimensions at 5 mm depth compared to the bite marks on BMR P2007.4.1.
Figure 8
Figure 8. Digitized comparisons between tyrannosaur maxillae and BMR P2007.4.1.
Interactive manipulation of digitized NextEngine 3D scan of a cast of the right maxilla of BHI #3033 and BMR P2007.4.1 caudal vertebra.
Figure 9
Figure 9. Digitized comparisons between BMR P2002.4.1 and BMR P2007.4.1.
Interactive manipulation of digitized NextEngine 3D scan of a cast of the right maxilla and dentary of BMR P2002.4.1, and BMR P2007.4.1 caudal vertebra.

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Grant support

The authors received no funding for this work.

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