Lower rotational inertia and larger leg muscles indicate more rapid turns in tyrannosaurids than in other large theropods

Eric Snively, Haley O'Brien, Donald M. Henderson, Heinrich Mallison, Lara A. Surring, Michael E. Burns, Thomas R. Holtz, Anthony P. Russell, Lawrence M. Witmer, Philip J. Currie, Scott A. Hartman, John R. Cotton

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Synopsis: Tyrannosaurid dinosaurs had large preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods. Methods: To compare turning capability in theropods, we regressed agility estimates against body mass, incorporating superellipse-based modeled mass, centers of mass, and rotational inertia (mass moment of inertia). Muscle force relative to body mass is a direct correlate of agility in humans, and torque gives potential angular acceleration. Agility scores therefore include rotational inertia values divided by proxies for (1) muscle force (ilium area and estimates of m. caudofemoralis longus cross-section), and (2) musculoskeletal torque. Phylogenetic ANCOVA (phylANCOVA) allow assessment of differences in agility between tyrannosaurids and non-tyrannosaurid theropods (accounting for both ontogeny and phylogeny). We applied conditional error probabilities a(p) to stringently test the null hypothesis of equal agility. Results: Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration). Implications: The capacity for relatively rapid turns in tyrannosaurids is ecologically intriguing in light of their monopolization of large (>400 kg), toothed dinosaurian predator niches in their habitats.

Original languageEnglish
Article number6432
JournalPeerJ
Volume2019
Issue number2
DOIs
StatePublished - 1 Jan 2019

Fingerprint

Muscle
Leg
legs
Torque
Phylogeny
Muscles
muscles
Dinosaurs
Ilium
Proxy
Computer Simulation
Ecosystem
torque
phylogeny
slicing
computer simulation
ontogeny
niches
predators
habitats

Keywords

  • Agility
  • Biomechanics
  • Phylogenetic ANCOVA
  • Predation
  • Theropoda
  • Tyrannosauridae

Cite this

Snively, Eric ; O'Brien, Haley ; Henderson, Donald M. ; Mallison, Heinrich ; Surring, Lara A. ; Burns, Michael E. ; Holtz, Thomas R. ; Russell, Anthony P. ; Witmer, Lawrence M. ; Currie, Philip J. ; Hartman, Scott A. ; Cotton, John R. / Lower rotational inertia and larger leg muscles indicate more rapid turns in tyrannosaurids than in other large theropods. In: PeerJ. 2019 ; Vol. 2019, No. 2.
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abstract = "Synopsis: Tyrannosaurid dinosaurs had large preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods. Methods: To compare turning capability in theropods, we regressed agility estimates against body mass, incorporating superellipse-based modeled mass, centers of mass, and rotational inertia (mass moment of inertia). Muscle force relative to body mass is a direct correlate of agility in humans, and torque gives potential angular acceleration. Agility scores therefore include rotational inertia values divided by proxies for (1) muscle force (ilium area and estimates of m. caudofemoralis longus cross-section), and (2) musculoskeletal torque. Phylogenetic ANCOVA (phylANCOVA) allow assessment of differences in agility between tyrannosaurids and non-tyrannosaurid theropods (accounting for both ontogeny and phylogeny). We applied conditional error probabilities a(p) to stringently test the null hypothesis of equal agility. Results: Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration). Implications: The capacity for relatively rapid turns in tyrannosaurids is ecologically intriguing in light of their monopolization of large (>400 kg), toothed dinosaurian predator niches in their habitats.",
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Snively, E, O'Brien, H, Henderson, DM, Mallison, H, Surring, LA, Burns, ME, Holtz, TR, Russell, AP, Witmer, LM, Currie, PJ, Hartman, SA & Cotton, JR 2019, 'Lower rotational inertia and larger leg muscles indicate more rapid turns in tyrannosaurids than in other large theropods', PeerJ, vol. 2019, no. 2, 6432. https://doi.org/10.7717/peerj.6432

Lower rotational inertia and larger leg muscles indicate more rapid turns in tyrannosaurids than in other large theropods. / Snively, Eric; O'Brien, Haley; Henderson, Donald M.; Mallison, Heinrich; Surring, Lara A.; Burns, Michael E.; Holtz, Thomas R.; Russell, Anthony P.; Witmer, Lawrence M.; Currie, Philip J.; Hartman, Scott A.; Cotton, John R.

In: PeerJ, Vol. 2019, No. 2, 6432, 01.01.2019.

Research output: Contribution to journalArticle

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T1 - Lower rotational inertia and larger leg muscles indicate more rapid turns in tyrannosaurids than in other large theropods

AU - Snively, Eric

AU - O'Brien, Haley

AU - Henderson, Donald M.

AU - Mallison, Heinrich

AU - Surring, Lara A.

AU - Burns, Michael E.

AU - Holtz, Thomas R.

AU - Russell, Anthony P.

AU - Witmer, Lawrence M.

AU - Currie, Philip J.

AU - Hartman, Scott A.

AU - Cotton, John R.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Synopsis: Tyrannosaurid dinosaurs had large preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods. Methods: To compare turning capability in theropods, we regressed agility estimates against body mass, incorporating superellipse-based modeled mass, centers of mass, and rotational inertia (mass moment of inertia). Muscle force relative to body mass is a direct correlate of agility in humans, and torque gives potential angular acceleration. Agility scores therefore include rotational inertia values divided by proxies for (1) muscle force (ilium area and estimates of m. caudofemoralis longus cross-section), and (2) musculoskeletal torque. Phylogenetic ANCOVA (phylANCOVA) allow assessment of differences in agility between tyrannosaurids and non-tyrannosaurid theropods (accounting for both ontogeny and phylogeny). We applied conditional error probabilities a(p) to stringently test the null hypothesis of equal agility. Results: Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration). Implications: The capacity for relatively rapid turns in tyrannosaurids is ecologically intriguing in light of their monopolization of large (>400 kg), toothed dinosaurian predator niches in their habitats.

AB - Synopsis: Tyrannosaurid dinosaurs had large preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods. Methods: To compare turning capability in theropods, we regressed agility estimates against body mass, incorporating superellipse-based modeled mass, centers of mass, and rotational inertia (mass moment of inertia). Muscle force relative to body mass is a direct correlate of agility in humans, and torque gives potential angular acceleration. Agility scores therefore include rotational inertia values divided by proxies for (1) muscle force (ilium area and estimates of m. caudofemoralis longus cross-section), and (2) musculoskeletal torque. Phylogenetic ANCOVA (phylANCOVA) allow assessment of differences in agility between tyrannosaurids and non-tyrannosaurid theropods (accounting for both ontogeny and phylogeny). We applied conditional error probabilities a(p) to stringently test the null hypothesis of equal agility. Results: Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration). Implications: The capacity for relatively rapid turns in tyrannosaurids is ecologically intriguing in light of their monopolization of large (>400 kg), toothed dinosaurian predator niches in their habitats.

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KW - Biomechanics

KW - Phylogenetic ANCOVA

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