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Reconstruction of the musculoskeletal system in an extinct lion

Andrew R Cuff, Anjali Goswami, and John R. Hutchinson

Plain Language Abstract

Soft tissues seldom preserve in fossils, therefore accurately rebuilding extinct species is incredibly difficult. Here we present a method for reconstructing the muscles of the extinct North American lion, Panthera atrox using published scaling equations from dissections of modern cat species, and CT scans of a modern lion (P. leo). By using a wrapping function that surrounds the muscles and skeleton, we are able to more accurately reconstruct the limbs (in terms of masses and centres of mass) for P. atrox than any previous method, as proved by a validation test on P. leo. We are also better able to estimate the body composition of P. atrox, not just in terms of muscles and bones, but also the viscera and fat content. Finally, the method presented here could be carried out on many more extant and extinct species using the same freely available software to produce more accurate digital reconstructions.

Resumen en Español

Reconstrucción del sistema músculo-esqueletal de un león extinto

Panthera atrox, un león extinto del Pleistoceno de América del Norte, es uno de los félidos más grandes que haya existido. Reconstrucciones previas han sido dependientes de especímenes compuestos y no se conocen especímenes que preserven tejidos blandos. Aquí presentamos una reconstrucción del espécimen más completo de P. atrox descubierto al día de hoy, a partir del cual hemos calculado parámetros biológicos clave incluyendo masa corporal. Usando ecuaciones de redimensionamiento previamente publicadas, estimamos el tamaño de la musculatura de los miembros y columna vertebral. Los músculos de un león moderno fueron modificados en escala a los tamaños esperados y colocados en el esqueleto. El cuerpo y los miembros fueron reconstruidos digitalmente (usando un método de hulling convexo) a partir del esqueleto antes de que este método fuera repetido con los segmentos de miembros musculados. Nuestros resultados de la repetición de este enfoque para un león moderno muestran que las reconstrucciones de hull convexo de músculo y hueso combinadas son las más precisas para reproducir las dimensiones de los miembros, incluyendo los centros de masa, de félidos grandes. A partir de las reconstrucciones también es posible estimar la composición corporal de P. atrox, lo cual permite realizar la reconstrucción de tejidos blandos más completa de esta especie extinta, incluyendo las propiedades biomecánicas de los miembros.

Palabras clave: reconstrucción de un fósil; músculos; Felidae; Panthera atrox, redimensionamiento

Traducción: Diana Elizabeth Fernández

Résumé en Français

text

Translator: Kenny J. Travouillon or Antoine Souron

Deutsche Zusammenfassung

Rekonstruktion des Bewegungsapparates eines ausgestorbenen Löwen

Panthera atrox, ein ausgestorbener Löwe aus dem Pleistozän von Nordamerika, ist einer der größten Feliden der je gelebt hat. Vorherige Rekonstruktionen beruhten immer auf zusammengesetzten Fundstücken und es gibt keine Funde mit Weichteilerhaltung. Hier präsentieren wir eine Rekonstruktion des bisher vollständigsten P. atrox Fundes, von dem wir die wichtigsten biologischen Parameter inklusive Körpermasse berechnen. Mithilfe von bereits veröffentlichten Skalierungsgleichungen kalkulierten wir die Größe der Extremitäten – und Wirbelsäulenmuskulatur. Die Muskeln eines heutigen Löwen wurden auf die angenommene Größe skaliert und auf dem Skelett platziert. Der Körper und die Extremitäten wurden vom Skelett digital rekonstruiert (mit einer konvexen Hülle Methode) bevor diese Methode mit den bemuskelten Beinsegmenten wiederholt wurde. Wir haben diesen Ansatz bei einem modernen Löwen angewandt und die Ergebnisse zeigen, dass die kombinierten Muskel und Knochen konvexe Hüllen Rekonstruktionen die Dimensionen der Extremitäten am genauesten reproduzieren, inklusive der Massenschwerpunkte bei großen Katzen. Mit den Rekonstruktionen können wir auch den Körperaufbau von P. atrox kalkulieren, was die umfassendste Weichteilrekonstruktion dieser ausgestorbenen Art ermöglicht, inklusive biomechanischer Eigenschaften der Extremitäten.

Schlüsselwörter: Fossilrekonstruktion; Muskeln; Felidae; Panthera atrox; Skalierung

Translator: Eva Gebauer

Arabic

Translator: Ashraf M.T. Elewa

 

 

APPENDIX 1.

Element and specimen numbers for the reconstruction of Panthera atrox.

Specimen number Element
LACMP23-555 Skull
LACMP23-4819 R dentary
LACMP23-3874 C1
LACMP23-3944 C2
LACMP23-3794 C3
LACMP23-1243 C4
LACMP23-3857 C5
LACMP23-1193 C6
LACMP23-4434 C7
LACMP23-666 T1 (T2 replicated)
LACMP23-666 T2
LACMP23-3719 T3
LACMP23-3764 T4
LACMP23-3764 T5 (T4 replicated)
LACMP23-3765 T6
LACMP23-3765 T7 (T6 replicated)
LACMP23-3754 T8
LACMP23-3715 T9
LACMP2458-19 T10 (“skeleton 2”)
LACMP23-3722 T11
LACMP23-9667 T12
LACMP23-3781 T13
LACMP23-3875 L1
LACMP23-3879 L2
LACMP23-3894 L3
LACMP23-3919 L4
LACMP23-4027 L5
LACMP23-3887 L6
LACMP23-3924 L7
LACMP23-3927 Sacrum
LACMP23-3700 Right scapula
LACMP23-1111 Left humerus
LACMP23-693 Left radius
LACMP23-3694 Left ulna
LACMP23-8741 Right innominate
LACMP23-918 Left femur
LACMP23-3696 Left tibia
NMS.Z.2015.128 Ribs, tail, manus, pes

APPENDIX 2.

Scaling equations for the forelimb muscles from Cuff et al. (2016a) and calculated muscle belly lengths for the mean, lower, and upper bounds of muscles for Panthera atrox. Serrat. vent. cerv. = m. serratus ventralis cervicus, Serrat. vent. thor. = m. serratus ventralis thoracis, Abd. dig. 1 = m. abductor digiti 1. Ext. = extensor, Flex. = flexor.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Latissimus dorsi 0.245 0.155 0.386 -0.757 0.646 0.400 1.374
Trapezius cervicis 0.447 0.168 1.19 -1.46 0.379 0.085 19.92
Trapezius thoracis 0.244 0.135 0.440 -1.13 0.275 0.154 0.783
Rhomboideus capitis 0.419 0.174 1.01 -1.34 0.428 0.116 9.804
Rhomboideus cervicis 0.340 0.147 0.782 -1.43 0.230 0.082 2.429
Rhomboideus thoracis 0.283 0.173 0.464 -1.35 0.204 0.113 0.538
Omotransversarius 0.250 0.201 0.312 -1.04 0.350 0.268 0.487
Cleidocephalicus 0.272 0.180 0.412 -1.02 0.405 0.248 0.853
Cleidobrachialis 0.299 0.238 0.376 -1.17 0.336 0.242 0.507
Serrat. Vent. Cerv. 0.244 0.186 0.321 -1.18 0.244 0.179 0.368
Serrat. Vent. Thor. 0.267 0.145 0.493 -1.24 0.240 0.125 0.801
Pectoralis superficialis 0.307 0.225 0.418 -1.14 0.372 0.241 0.674
Pectoralis profundus 0.395 0.236 0.663 -1.11 0.642 0.274 2.672
Supraspinatus 0.327 0.268 0.398 -1.22 0.344 0.252 0.505
Infraspinatus 0.265 0.194 0.363 -1.20 0.261 0.178 0.440
Deltoideus acromion 0.297 0.231 0.381 -1.42 0.184 0.130 0.289
Deltoideus spinous 0.267 0.245 0.292 -1.33 0.195 0.173 0.222
Teres major 0.286 0.232 0.353 -1.21 0.286 0.214 0.408
Subscapularis 0.279 0.213 0.365 -1.24 0.254 0.179 0.403
Teres minor 0.356 0.154 0.819 -1.87 0.091 0.031 1.076
Coracobrachialis 1.09 0.468 2.54 -2.72 0.644 0.023 1491
Triceps longus 0.417 0.173 1.005 -1.43 0.348 0.095 7.992
Triceps lateralis 0.249 0.198 0.313 -1.13 0.277 0.211 0.389
Triceps medius 0.277 0.199 0.385 -1.24 0.253 0.167 0.452
Triceps accessory 0.308 0.269 0.352 -1.26 0.281 0.229 0.357
Biceps brachi 0.259 0.214 0.315 -1.19 0.257 0.201 0.346
Brachialis 0.412 0.213 0.794 -1.48 0.297 0.103 2.279
Anconeus 0.301 0.225 0.404 -1.48 0.165 0.110 0.286
Ext. carpi radialis 0.305 0.224 0.415 -1.22 0.310 0.201 0.558
Ext. digitorum communis 0.296 0.134 0.653 -1.31 0.236 0.100 1.587
Ext. digitorum lateralis 0.575 0.270 1.23 -1.72 0.415 0.081 13.3
Ext. carpi ulnaris 0.287 0.195 0.423 -1.24 0.264 0.161 0.544
Flex. carpi ulnaris ulnar 0.264 0.162 0.432 -1.19 0.262 0.151 0.641
Flex. carpi ulnaris humeral 0.275 0.185 0.409 -1.17 0.295 0.182 0.604
Brachioradialis 1.37 0.676 2.77 -2.79 2.410 0.060 4289
Supinator 0.316 0.220 0.454 -1.57 0.147 0.088 0.307
Pronator teres 0.316 0.232 0.431 -1.40 0.216 0.138 0.398
Pronator quadratus 0.497 0.326 0.756 -1.75 0.254 0.102 1.014
Flex. carpi radialis 0.305 0.256 0.363 -1.29 0.259 0.199 0.353
Flex. digitorum complex 0.237 0.163 0.345 -1.10 0.284 0.191 0.505
Abd. Dig. 1 0.576 0.388 0.856 -1.71 0.418 0.153 1.859

APPENDIX 3.

Scaling equations for the forelimb muscles from Cuff et al. (2016a) and calculated tendon lengths for the mean, lower, and upper bounds of muscles for Panthera atrox. Abd. dig. 1 = m. abductor digiti 1. Ext. = extensor, Flex. = flexor.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Cleidobrachialis 0.945 0.433 2.06 -3.04 0.140 0.009 54.70
Supraspinatus 0.719 0.032 16.2 -3.01 0.045 0.001 2.44x1034
Infraspinatus 1.18 0.751 1.84 -3.42 0.203 0.021 7.029
Deltoideus spinous 1.29 0.072 22.9 -3.92 0.113 0.000 1.21x1049
Teres major -0.687 -1.649 -0.286 -1.14 0.002 0.000 0.016
Subscapularis 0.350 0.199 0.614 -2.46 0.022 0.010 0.092
Triceps longus 0.727 0.420 1.26 -2.57 0.130 0.025 2.206
Triceps lateralis 1.03 0.387 2.77 -3.39 0.101 0.003 1029
Triceps medius 0.598 0.225 1.59 -2.25 0.136 0.019 26.37
Biceps brachi 0.289 0.168 0.497 -1.66 0.102 0.054 0.310
Brachialis 0.530 0.285 0.983 -2.46 0.059 0.016 0.658
Ext. carpi radialis 0.336 0.205 0.552 -1.57 0.163 0.081 0.515
Ext. digitorum communis -0.661 -1.580 -0.276 -0.313 0.014 0.000 0.111
Ext. digitorum lateralis 0.242 0.123 0.475 -1.332 0.169 0.090 0.588
Ext. carpi ulnaris 0.289 0.134 0.624 -1.457 0.163 0.071 0.977
Flex. carpi ulnaris ulnar -0.310 -0.823 -0.117 -0.964 0.021 0.001 0.058
Flex. carpi ulnaris humeral 0.534 0.111 2.575 -2.20 0.108 0.011 5765
Supinator -1.37 -8.50 -0.222 0.503 0.002 0.000 0.974
Pronator quadratus 0.552 0.154 1.987 -2.41 0.073 0.009 154.6
Flex. carpi radialis 0.212 0.088 0.511 -1.58 0.081 0.042 0.399
Flex. digitorum complex 0.262 0.151 0.456 -1.36 0.177 0.098 0.496
Abd. Dig. 1 0.691 0.365 1.308 -2.25 0.223 0.039 6.010

APPENDIX 4.

Scaling equations for the forelimb muscles from Cuff et al. (2016a) and calculated muscle belly masses for the mean, lower,and upper bounds of muscles for Panthera atrox. Serrat. vent. cerv. = m. serratus ventralis cervicus, Serrat. vent. thor. = m. serratus ventralis thoracis, Abd. dig. 1 = m. abductor digiti 1. Ext. = extensor, Flex. = flexor.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Latissimus dorsi 1.12 0.993 1.26 -2.34 1.776 0.906 3.792
Trapezius cervicis 1.05 0.913 1.22 -3.08 0.229 0.108 0.543
Trapezius thoracis 1.07 0.867 1.32 -3.09 0.242 0.083 0.910
Rhomboideus capitis 1.27 0.877 1.84 -3.58 0.232 0.028 4.913
Rhomboideus cervicis 1.15 0.859 1.55 -3.02 0.444 0.093 3.618
Rhomboideus thoracis 1.07 0.734 1.57 -3.30 0.156 0.025 2.231
Omotransversarius 1.08 0.877 1.34 -3.28 0.169 0.056 0.656
Cleidocephalicus 1.18 0.874 1.58 -3.04 0.484 0.096 4.238
Cleidobrachialis 1.14 0.939 1.39 -2.94 0.509 0.171 1.915
Serrat. Vent. Cerv. 0.977 0.702 1.36 -2.55 0.523 0.121 4.027
Serrat. Vent. Thor. 0.949 0.779 1.16 -2.46 0.552 0.223 1.672
Pectoralis superficialis 1.22 0.917 1.63 -3.08 0.567 0.111 4.987
Pectoralis profundus 1.07 0.887 1.29 -2.20 1.923 0.720 6.290
Supraspinatus 1.02 0.844 1.23 -2.36 1.001 0.395 3.082
Infraspinatus 0.991 0.799 1.23 -2.45 0.699 0.251 2.491
Deltoideus acromion 1.04 0.881 1.24 -3.21 0.162 0.068 0.451
Deltoideus spinous 1.08 0.877 1.33 -3.22 0.190 0.064 0.725
Teres major 1.07 0.921 1.25 -2.74 0.554 0.246 1.429
Subscapularis 0.963 0.797 1.16 -2.41 0.670 0.276 1.959
Teres minor 0.982 0.796 1.21 -3.73 0.035 0.013 0.120
Coracobrachialis 1.55 0.734 3.26 -4.46 0.133 0.002 1233
Triceps longus 1.06 0.922 1.23 -2.27 1.562 0.732 3.744
Triceps lateralis 1.05 0.906 1.22 -2.67 0.582 0.270 1.417
Triceps medius 1.05 0.840 1.31 -3.14 0.197 0.064 0.804
Triceps accessory 0.968 0.758 1.23 -3.15 0.123 0.040 0.513
Biceps brachi 1.06 0.895 1.25 -2.73 0.531 0.223 1.485
Brachialis 1.00 0.652 1.54 -3.19 0.138 0.021 2.473
Anconeus 1.05 0.801 1.37 -3.57 0.072 0.019 0.404
Ext. carpi radialis 1.03 0.822 1.30 -3.09 0.201 0.065 0.828
Ext. digitorum communis 1.17 0.929 1.48 -3.45 0.186 0.051 0.945
Ext. digitorum lateralis 1.02 0.761 1.36 -3.63 0.054 0.014 0.300
Ext. carpi ulnaris 1.10 0.681 1.78 -3.66 0.077 0.008 2.868
Flex. carpi ulnaris ulnar 1.19 0.814 1.74 -3.61 0.139 0.019 2.628
Flex. carpi ulnaris humeral 1.10 0.933 1.30 -3.34 0.162 0.066 0.474
Brachioradialis 1.49 1.261 1.75 -4.11 0.218 0.065 0.900
Supinator 1.02 0.747 1.40 -3.77 0.039 0.009 0.292
Pronator teres 1.03 0.836 1.28 -3.29 0.128 0.044 0.476
Pronator quadratus 1.22 0.925 1.61 -3.98 0.071 0.015 0.574
Flex. carpi radialis 0.929 0.792 1.09 -3.39 0.058 0.028 0.138
Flex. digitorum complex 0.998 0.877 1.13 -2.61 0.499 0.262 1.038
Abd. Dig. 1 0.861 0.566 1.31 -3.41 0.039 0.008 0.425

APPENDIX 5.

Scaling equations for the forelimb muscles from Cuff et al. (2016a) and calculated tendon masses for the mean, lower, and upper bounds of muscles for Panthera atrox. Abd. dig. 1 = m. abductor digiti 1, Ext. = extensor, Flex. = flexor.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Cleidobrachialis -2.71 -9.826 -0.748 0.836 0.000 0.000 0.127
Supraspinatus 0.651 0.087 4.88 -4.39 0.001 0.000 8.38x106
Infraspinatus 1.289 0.636 2.61 -4.40 0.038 0.001 44.46
Deltoideus spinous -0.349 -5.351 -0.023 -2.54 0.000 0.000 0.003
Teres major 0.621 0.376 1.027 -4.41 0.001 0.000 0.009
Triceps longus 0.852 0.431 1.68 -4.22 0.006 0.001 0.470
Triceps lateralis 1.02 0.627 1.65 -4.65 0.005 0.001 0.154
Triceps medius 1.70 0.772 3.75 -5.94 0.010 0.000 548.4
Biceps brachi 0.933 0.748 1.16 -4.10 0.012 0.004 0.040
Brachialis 0.943 0.495 1.80 -4.71 0.003 0.000 0.287
Ext. carpi radialis 0.915 0.765 1.09 -4.24 0.008 0.003 0.019
Ext. digitorum communis 1.44 0.970 2.12 -4.46 0.074 0.006 2.906
Ext. digitorum lateralis 0.958 0.722 1.27 -4.32 0.008 0.002 0.042
Ext. carpi ulnaris 0.833 0.455 1.52 -4.23 0.005 0.001 0.199
Flex. carpi ulnaris ulnar 1.16 0.743 1.82 -5.21 0.003 0.000 0.101
Flex. carpi ulnaris humeral 0.984 0.643 1.51 -5.08 0.002 0.000 0.026
Supinator 1.57 0.251 9.79 -6.08 0.004 0.000 4.09x106
Pronator quadratus 0.953 0.310 2.93 -4.58 0.004 0.000 162.0
Flex. carpi radialis 0.660 0.450 0.967 -4.28 0.002 0.001 0.009
Flex. digitorum complex 0.943 0.692 1.29 -3.24 0.087 0.023 0.541
Abd. Dig. 1 0.730 0.403 1.32 -4.24 0.003 0.000 0.066

APPENDIX 6.

Scaling equations for the hindlimb muscles from Cuff et al. (2016b) and calculated muscle belly lengths for the mean, lower, and upper bounds of muscles for Panthera atrox. Gastroc. = gastrocnemius, dig. = digitorum, supefic. = superficialis.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Biceps femoris 0.264 0.172 0.406 -0.988 0.420 0.257 0.895
Caudofemoralis 0.281 0.185 0.426 -1.079 0.373 0.223 0.811
Sartorius 0.327 0.258 0.414 -0.941 0.654 0.453 1.040
Tensor fascia latae 0.292 0.221 0.387 -1.398 0.190 0.130 0.315
Vastus lateralis 0.286 0.232 0.352 -1.072 0.389 0.293 0.553
Rectus femoris 0.366 0.204 0.658 -1.227 0.419 0.176 1.984
Vastus medius 0.268 0.210 0.342 -1.077 0.350 0.257 0.519
Vastus intermedius 0.554 0.264 1.164 -1.597 0.486 0.103 12.60
Semitendinosus 0.279 0.242 0.322 -0.980 0.464 0.381 0.583
Semimembranosus 0.564 0.270 1.178 -1.451 0.718 0.150 18.95
Gracilis 0.244 0.132 0.449 -1.155 0.257 0.142 0.770
Gluteus superficialis 0.321 0.213 0.484 -1.479 0.184 0.103 0.439
Gluteus medius 0.345 0.290 0.412 -1.405 0.249 0.185 0.354
Gluteus profundus 0.353 0.255 0.489 -1.454 0.231 0.137 0.476
Piriformis 0.167 0.101 0.276 -1.432 0.090 0.063 0.162
Gemelli 0.380 0.188 0.769 -1.693 0.154 0.055 1.226
Quadratus femoris 0.301 0.228 0.396 -1.600 0.125 0.085 0.208
Obturator externus 0.330 0.271 0.402 -1.671 0.124 0.091 0.182
Obturator internus 0.288 0.172 0.480 -1.595 0.118 0.064 0.329
Pectineus 0.455 0.234 0.883 -1.626 0.268 0.083 2.625
Adductor magnus 0.305 0.198 0.471 -1.114 0.392 0.221 0.900
Adductor brevis 0.310 0.175 0.551 -1.388 0.214 0.104 0.773
Iliacus 1.388 0.090 21.318 -3.465 0.564 0.001 8.35x104
Psoas major 0.384 0.256 0.575 -1.142 0.558 0.283 1.547
Psoas minor 0.318 0.201 0.504 -1.165 0.373 0.200 1.004
Gastroc. lateralis 0.327 0.219 0.490 -1.235 0.334 0.187 0.796
Gastroc. medius 0.262 0.216 0.317 -1.142 0.291 0.228 0.392
Superfic. dig. flexor 0.264 0.131 0.530 -1.144 0.293 0.145 1.211
Soleus 0.212 0.147 0.304 -1.061 0.268 0.191 0.439
Dig. extensor longus 0.265 0.150 0.468 -1.150 0.291 0.157 0.859
Tibialis cranialis 0.237 0.130 0.432 -1.095 0.284 0.160 0.800
Popliteus 0.375 0.266 0.530 -1.594 0.189 0.105 0.432
Dig. extensor lateralis 0.265 0.196 0.359 -1.282 0.215 0.149 0.354
Peroneus longus 0.236 0.145 0.383 -1.201 0.222 0.137 0.486
Peroneus brevis 0.192 0.112 0.330 -1.144 0.200 0.130 0.400
Deep digital flexor medial 0.307 0.196 0.480 -1.236 0.298 0.165 0.751
Deep digital flexor lateral 0.406 0.171 0.965 -1.430 0.324 0.092 6.383
Tibialis caudalis 0.413 0.256 0.666 -1.522 0.272 0.118 1.046

APPENDIX 7.

Scaling equations for the hindlimb muscles from Cuff et al. (2016b) and calculated tendon lengths for the mean, lower, and upper bounds of muscles for Panthera atrox. Gastroc. = gastrocnemius, Dig. = digitorum, Supefic. = superficialis.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Caudofemoralis 0.496 0.304 0.812 -1.612 0.345 0.123 1.854
Tensor fascia latae 0.330 0.160 0.679 -1.298 0.293 0.119 1.880
Rectus femoris 1.307 0.099 17.288 -3.216 0.650 0.001 6.86x103
Vastus medius 0.264 0.144 0.483 -2.155 0.029 0.015 0.092
Vastus intermedius -0.875 -20.805 -0.037 -0.659 0.002 0.000 0.180
Semitendinosus 0.440 0.230 0.841 -1.893 0.134 0.044 1.138
Semimembranosus 0.467 0.162 1.348 -2.446 0.043 0.008 4.746
Gracilis 0.558 0.093 3.355 -2.349 0.088 0.007 2.65x105
Gluteus profundus -0.604 -3.758 -0.097 -0.893 0.005 0.000 0.076
Piriformis 0.278 0.015 5.158 -2.279 0.023 0.006 4.69x109
Obturator internus 0.353 0.068 1.842 -1.924 0.078 0.017 220.4
Psoas major 0.074 0.003 1.689 -1.407 0.058 0.040 320.7
Psoas minor 0.182 0.035 0.937 -1.563 0.072 0.033 4.059
Gastroc. lateralis 0.208 0.102 0.424 -1.624 0.072 0.041 0.228
Gastroc. medius 0.470 0.235 0.939 -1.952 0.137 0.039 1.677
Superfic. dig. flexor 0.887 0.369 2.134 -2.483 0.373 0.023 289.5
Soleus 0.058 0.002 1.424 -1.749 0.024 0.018 35.43
Dig. extensor longus 0.445 0.188 1.051 -1.601 0.269 0.068 6.825
Tibialis cranialis 0.366 0.183 0.731 -1.803 0.111 0.042 0.777
Popliteus 0.564 0.075 4.223 -2.329 0.095 0.007 2.85x107
Dig. extensor lateralis 0.427 0.245 0.745 -1.484 0.320 0.121 1.747
Peroneus longus 0.331 0.148 0.738 -1.546 0.166 0.063 1.456
Peroneus brevis 0.648 0.239 1.753 -2.117 0.242 0.027 87.82
Deep digital flexor medial 0.336 0.148 0.760 -1.302 0.299 0.110 2.877
Deep digital flexor lateral 0.525 0.272 1.015 -1.550 0.465 0.120 6.322
Tibialis caudalis 0.313 0.132 0.740 -1.469 0.180 0.069 1.759

APPENDIX 8.

Scaling equations for the hindlimb muscles from Cuff et al. (2016b) and calculated muscle belly masses for the mean, lower, and upper bounds of muscles for Panthera atrox. Gastroc. = gastrocnemius, Dig. = digitorum, Supefic. = superficialis.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Biceps femoris 0.998 0.862 1.155 -2.124 1.537 0.745 3.553
Caudofemoralis 1.353 0.950 1.928 -3.423 0.515 0.060 11.03
Sartorius 1.090 0.956 1.242 -2.636 0.775 0.380 1.745
Tensor fascia latae 1.240 0.976 1.575 -3.138 0.542 0.133 3.236
Vastus lateralis 0.955 0.788 1.156 -2.228 0.962 0.396 2.815
Rectus femoris 0.964 0.841 1.103 -2.391 0.693 0.361 1.462
Vastus medius 0.924 0.732 1.165 -2.452 0.487 0.175 1.769
Vastus intermedius 0.796 0.650 0.976 -2.619 0.168 0.077 0.439
Semitendinosus 1.093 0.929 1.286 -2.697 0.684 0.285 1.915
Semimembranosus 1.061 0.789 1.428 -2.322 1.369 0.320 9.683
Gracilis 1.213 0.767 1.917 -3.082 0.534 0.050 22.90
Gluteus superficialis 1.053 0.832 1.334 -3.257 0.153 0.047 0.681
Gluteus medius 1.220 1.120 1.330 -2.800 1.063 0.622 1.905
Gluteus profundus 0.906 0.743 1.106 -3.147 0.090 0.037 0.261
Piriformis 0.828 0.630 1.087 -2.948 0.093 0.033 0.372
Gemelli 1.155 0.827 1.612 -3.510 0.146 0.025 1.675
Quadratus femoris 0.785 0.556 1.109 -3.160 0.046 0.013 0.256
Obturator externus 1.085 0.909 1.295 -3.288 0.168 0.066 0.516
Obturator internus 1.063 0.784 1.441 -3.214 0.178 0.040 1.331
Pectineus 0.903 0.635 1.285 -3.124 0.093 0.022 0.711
Adductor magnus 1.056 0.729 1.530 -2.374 1.181 0.206 14.8
Adductor brevis 0.878 0.547 1.409 -2.710 0.211 0.036 3.574
Iliacus 2.272 0.456 11.327 -5.532 0.538 0.000 5.12x102
Psoas major 1.172 0.849 1.619 -2.821 0.785 0.140 8.520
Psoas minor 1.098 0.801 1.505 -3.159 0.242 0.050 2.131
Gastroc. lateralis 0.923 0.721 1.181 -2.562 0.377 0.129 1.496
Gastroc. medius 0.874 0.737 1.036 -2.545 0.302 0.146 0.718
Superfic. dig. flexor 0.842 0.623 1.138 -2.876 0.119 0.037 0.575
Soleus 0.850 0.669 1.080 -2.880 0.123 0.047 0.419
Dig. extensor longus 0.902 0.527 1.544 -3.166 0.084 0.011 2.577
Tibialis cranialis 1.025 0.725 1.449 -3.046 0.213 0.043 2.00
Popliteus 0.846 0.683 1.048 -3.225 0.054 0.023 0.159
Dig. extensor lateralis 0.835 0.522 1.336 -3.518 0.026 0.005 0.378
Peroneus longus 1.324 0.768 2.283 -3.800 0.185 0.010 30.82
Peroneus brevis 0.912 0.600 1.387 -3.496 0.041 0.008 0.500
Deep digital flexor medial 1.038 0.726 1.485 -3.188 0.165 0.031 1.788
Deep digital flexor lateral 1.017 0.630 1.643 -3.220 0.137 0.017 3.865
Tibialis caudalis 1.263 0.961 1.660 -3.856 0.117 0.023 0.975

APPENDIX 9.

Scaling equations for the hindlimb muscles from Cuff et al. (2016b) and calculated tendon masses for the mean, lower, and upper bounds of muscles for Panthera atrox. Gastroc. = gastrocnemius, Dig. = digitorum, Supefic. = superficialis.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Caudofemoralis 1.190 0.455 3.111 -4.484 0.019 0.000 527.3
Tensor fascia latae 0.964 0.690 1.347 -3.599 0.043 0.010 0.333
Rectus femoris 1.441 0.059 35.233 -4.439 0.079 0.000 1.53x1077
Vastus medius 1.029 0.621 1.704 -4.782 0.004 0.000 0.147
Vastus intermedius -0.488 -11.839 -0.020 -2.481 0.000 0.000 0.003
Semitendinosus 0.962 0.607 1.525 -4.575 0.005 0.001 0.091
Semimembranosus 0.750 0.419 1.342 -4.321 0.003 0.000 0.061
Gracilis 1.225 0.445 3.372 -4.638 0.016 0.000 1492
Gluteus profundus 0.574 0.176 1.876 -4.360 0.001 0.000 0.971
Piriformis 0.893 0.229 3.492 -4.675 0.002 0.000 2602
Obturator internus 1.035 0.127 8.421 -4.487 0.008 0.000 1.05x1015
Psoas major 1.725 1.080 2.756 -5.129 0.074 0.002 18.08
Psoas minor 0.756 0.212 2.692 -4.446 0.002 0.000 61.68
Gastroc. lateralis 1.014 0.642 1.601 -4.036 0.021 0.003 0.471
Gastroc. medius 0.973 0.547 1.729 -3.929 0.021 0.002 1.19
Superfic. dig. flexor 1.710 1.153 2.536 -4.468 0.311 0.016 25.49
Soleus 0.770 0.052 11.341 -4.509 0.002 0.000 5.82x1021
Dig. extensor longus 1.568 1.063 2.313 -4.610 0.105 0.007 5.61
Tibialis cranialis 1.010 0.666 1.532 -4.696 0.004 0.001 0.071
Popliteus 0.814 0.423 1.566 -4.388 0.003 0.000 0.174
Dig. extensor lateralis 0.829 0.595 1.155 -4.389 0.003 0.001 0.019
Peroneus longus 1.856 0.726 4.745 -5.506 0.062 0.000 3.06x105
Peroneus brevis 0.950 0.553 1.633 -4.589 0.004 0.000 0.156
Deep digital flexor medial 1.335 0.711 2.508 -4.300 0.062 0.002 32.40
Deep digital flexor lateral 1.035 0.659 1.625 -3.791 0.040 0.005 0.940
Tibialis caudalis 1.129 0.630 2.023 -4.585 0.011 0.001 1.266

APPENDIX 10.

Scaling equations for the vertebral muscles from Cuff et al. (2016a, 2016b) and calculated muscle belly lengths for the mean, lower, and upper bounds of muscles for Panthera atrox. Longis. = longissimus, Iliocost. = iliocostalis, Multifid. = multifidus.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Rectus capitis 0.208 0.080 0.541 -1.43 0.112 0.057 0.662
Splenius cervicis 0.234 0.174 0.316 -0.946 0.395 0.286 0.610
Serratus dorsalis cranialis 0.239 0.079 0.719 -1.45 0.127 0.054 1.647
Serratus dorsalis caudalis 0.186 0.070 0.496 -1.50 0.085 0.046 0.444
Semispinalis capitis biventer 1.36 0.683 2.71 -2.55 4.009 0.108 5326
Semispinalis capitis complexus 0.336 0.162 0.700 -1.11 0.470 0.185 3.267
Spinalis cervicis 0.240 0.098 0.591 -1.06 0.314 0.147 2.040
Spinalis thoracis 0.309 0.252 0.380 -0.910 0.641 0.472 0.934
Longissimus capitis 0.287 0.130 0.633 -1.16 0.323 0.140 2.044
Longissimus cervicis 0.227 0.121 0.425 -0.920 0.405 0.230 1.163
Longissimus thoracis 0.340 0.208 0.556 -0.872 0.827 0.409 2.612
Iliocostalis thoracis 0.266 0.183 0.386 -0.809 0.640 0.412 1.215
Multifidis throacis 0.305 0.213 0.435 -0.852 0.713 0.439 1.429
Longis. lumborum 0.603 0.197 1.849 -1.403 0.987 0.113 758.5
Iliocost. lumborum 0.358 0.216 0.594 -1.030 0.630 0.295 2.217
Multifid. lumborum 0.319 0.166 0.613 -0.919 0.661 0.293 3.165

 

APPENDIX 11.

Scaling equations for the vertebral muscles from Cuff et al. (2016a, 2016b) and calculated tendon lengths for the mean, lower, and upper bounds of muscles for Panthera atrox.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Serratus dorsalis cranialis 1.35 0.217 8.42 -3.772 0.228 0.001 5.43x105
Serratus dorsalis caudalis -1.53 -6.001 -0.389 0.484 0.001 0.000 0.382

APPENDIX 12.

Scaling equations for the vertebral muscles from Cuff et al. (2016a, 2016b) and calculated muscle belly masses for the mean, lower, and upper bounds of muscles for Panthera atrox.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Rectus capitis 0.679 0.472 0.977 -2.58 0.098 0.032 0.480
Splenius cervicis 1.04 0.785 1.39 -2.86 0.366 0.092 2.31
Serratus dorsalis cranialis 1.00 0.523 1.93 -3.23 0.124 0.009 17.1
Serratus dorsalis caudalis 0.893 0.701 1.14 -3.17 0.080 0.029 0.294
Semispinalis capitis biventer 1.05 0.899 1.24 -2.93 0.325 0.143 0.9
Semispinalis capitis complexus 1.13 0.854 1.51 -3.12 0.325 0.073 2.38
Spinalis cervicis 0.992 0.532 1.85 -2.77 0.336 0.029 32.4
Spinalis thoracis 1.26 0.941 1.69 -2.98 0.877 0.160 8.52
Longissimus capitis 0.867 0.488 1.54 -3.21 0.064 0.008 2.32
Longissimus cervicis 0.673 0.338 1.34 -2.40 0.143 0.024 4.98
Longissimus thoracis 0.821 0.542 1.24 -1.94 0.916 0.207 8.76
Iliocostalis thoracis 0.899 0.743 1.09 -2.79 0.195 0.085 0.533
Multifidis throacis 0.893 0.784 1.02 -2.52 0.355 0.198 0.690
Longis. lumborum 1.26 0.652 2.43 -2.55 2.34 0.092 1230
Iliocost. lumborum 1.19 0.860 1.65 -2.58 1.49 0.258 17.0
Multifid. lumborum 0.942 0.705 1.26 -2.60 0.381 0.108 2.05

 

 

APPENDIX 13.

Scaling equations for the vertebral muscles from Cuff et al. (2016a, 2016b) and calculated tendon masses for the mean, lower, and upper bounds of muscles for Panthera atrox. Longis. = longissimus, Iliocost. = iliocostalis, Multifid. = multifidus.

Muscle Slope Lower limit Upper limit Intercept Mean Lower Upper
Serratus dorsalis cranialis 1.36 0.609 3.03 -4.63 0.033 0.001 247.5
Serratus dorsalis caudalis 1.40 0.639 3.06 -4.94 0.020 0.000 141.3
 

TABLE 1. Forelimb muscle belly and tendon lengths and masses as predicted from Cuff et al. (2016a). Serrat. vent. cerv. = m. serratus ventralis cervicus, Serrat. vent. thor. = m. serratus ventralis thoracis, Abd. dig. 1 = m. abductor digiti 1. Ext. = extensor, Flex. = flexor.

Muscle Belly length
(m)
Tendon length
(m)
Belly mass
(kg)
Tendon mass (kg)
Latissimus dorsi 0.646   1.776  
Trapezius cervicis 0.379   0.229  
Trapezius thoracis 0.275   0.242  
Rhomboideus capitis 0.428   0.232  
Rhomboideus cervicis 0.230   0.444  
Rhomboideus thoracis 0.204   0.156  
Omotransversarius 0.350   0.169  
Cleidocephalicus 0.405   0.484  
Cleidobrachialis 0.336 0.140 0.509  
Serrat. vent. cerv. 0.244   0.523  
Serrat. vent. thor. 0.240   0.552  
Pectoralis superficialis 0.372   0.567  
Pectoralis profundus 0.642   1.923  
Supraspinatus 0.344 0.045 1.001 0.001
Infraspinatus 0.261 0.203 0.699 0.038
Deltoideus acromion 0.184   0.162  
Deltoideus spinous 0.195 0.113 0.190 0.000
Teres major 0.286 0.002 0.554 0.001
Subscapularis 0.254 0.022 0.670 1.000
Teres minor 0.091   0.035  
Coracobrachialis 0.644   0.133  
Triceps longus 0.348 0.130 1.562 0.006
Triceps lateralis 0.277 0.101 0.582 0.005
Triceps medius 0.253 0.136 0.197 0.010
Triceps accessory 0.281   0.123  
Biceps brachi 0.257 0.102 0.531 0.012
Brachialis 0.297 0.059 0.138 0.003
Anconeus 0.165   0.072  
Ext. carpi radialis 0.310 0.163 0.201 0.008
Ext. digitorum communis 0.236 0.014 0.186 0.074
Ext. digitorum lateralis 0.415 0.169 0.054 0.008
Ext. carpi ulnaris 0.264 0.163 0.077 0.005
Flex. carpi ulnaris ulnar 0.262 0.021 0.139 0.003
Flex. carpi ulnaris humeral 0.295 0.108 0.162 0.002
Brachioradialis 2.410   0.218  
Supinator 0.147 0.002 0.039 0.004
Pronator teres 0.216   0.128  
Pronator quadratus 0.254 0.073 0.071 0.004
Flex. carpi radialis 0.259 0.081 0.058 0.002
Flex. digitorum complex 0.284 0.177 0.499 0.087
Abd. dig. 1 0.418 0.223 0.039 0.003

 

TABLE 2. Hindlimb muscle belly and tendon lengths and masses as predicted from Cuff et al. (2016b). Gastroc. = gastrocnemius, Dig. = digitorum, Supefic. = superficialis.

Muscle Belly length
(m)
Tendon length
(m)
Belly mass
(kg)
Tendon mass
(kg)
Biceps femoris 0.420   1.537  
Caudofemoralis 0.373 0.345 0.515 0.019
Sartorius 0.654   0.775  
Tensor fascia latae 0.190 0.293 0.542 0.043
Vastus lateralis 0.389   0.962  
Rectus femoris 0.419 0.650 0.693 0.079
Vastus medius 0.350 0.029 0.487 0.004
Vastus intermedius 0.486 0.002 0.168 0.000
Semitendinosus 0.464 0.134 0.684 0.005
Semimembranosus 0.718 0.043 1.369 0.003
Gracilis 0.257 0.088 0.534 0.016
Gluteus superficialis 0.184   0.153  
Gluteus medius 0.249   1.063  
Gluteus profundus 0.231 0.005 0.090 0.001
Piriformis 0.090 0.023 0.093 0.002
Gemelli 0.154   0.146  
Quadratus femoris 0.125   0046  
Obturator externus 0.124   0.168  
Obturator internus 0.118 0.078 0.178 0.008
Pectineus 0.268   0.093  
Adductor magnus 0.392   1.181  
Adductor brevis 0.214   0.211  
Iliacus 0.564   0.538  
Psoas major 0.558 0.058 0.785 0.074
Psoas minor 0.373 0.072 0.242 0.002
Gastroc. lateralis 0.334 0.072 0.377 0.021
Gastroc. medius 0.291 0.137 0.302 0.021
Superfic. dig. flexor 0.293 0.373 0.119 0.311
Soleus 0.268 0.024 0.123 0.002
Dig. extensor longus 0.291 0.269 0.084 0.105
Tibialis cranialis 0.284 0.111 0.213 0.004
Popliteus 0.189 0.095 0.054 0.003
Dig. extensor lateralis 0.215 0.320 0.026 0.003
Peroneus longus 0.222 0.166 0.185 0.062
Peroneus brevis 0.200 0.242 0.041 0.004
Deep digital flexor medial 0.298 0.299 0.165 0.062
Deep digital flexor lateral 0.324 0.465 0.137 0.040
Tibialis caudalis 0.272 0.180 0.117 0.011

 

TABLE 3. Vertebral muscle belly and tendon lengths and masses as predicted from Cuff et al. (2016a, b). Longis. = longissimus, Iliocost. = iliocostalis, Multifid. = multifidus.

Muscle Belly length
(m)
Tendon length
(m)
Belly mass
(kg)
Tendon mass
(kg)
Rectus capitis 0.112   0.098  
Splenius cervicis 0.395   0.366  
Serratus dorsalis cranialis 0.127 0.228 0.124 0.033
Serratus dorsalis caudalis 0.085 0.001 0.080 0.020
Semispinalis capitis biventer 4.009   0.325  
Semispinalis capitis complexus 0.470   0.325  
Spinalis cervicis 0.314   0.336  
Spinalis thoracis 0.641   0.877  
Longissimus capitis 0.323   0.064  
Longissimus cervicis 0.405   0.143  
Longissimus thoracis 0.827   0.916  
Iliocostalis thoracis 0.640   0.195  
Multifidis throacis 0.713   0.355  
Longis. lumborum 2.342   0.987  
Iliocost. lumborum 1.494   0.630  
Multifid. lumborum 0.381   0.661  

 

TABLE 4. Body composition of Panthera atrox from reconstructed muscles and dissections of extant P. leo specimens (Davis, 1962). “Muscle recon” is the sum of the reconstructed forelimb, hindlimb, and vertebral muscles. Additional muscle is the remaining expected muscle using the body compositions for modern lions (Davis, 1962) i.e., 57.1% - “Muscle recon”.

  Body Forelimb
muscles
Hindlimb
muscles
Vertebral
muscle
Muscle
recon
Additional
muscle
Bone Adipose Organs Skin and fur Blood and waste
Mass (kg) 207 35.2 32.2 16.9 84.4 33.7 25.7 5.5 24.4 23.8 9.56
Percentage (%) 100 17.0 15.6 8.18 40.8 16.3 12.4 2.67 11.8 11.5 4.62

 

TABLE 5. Panthera leo limb segment masses from the different mass estimate methods. “Flesh” is the weight calculated for the segment volumes (multiplied by 1060 kg m-3) from CT segmentation. “Reconstruction” was based on the muscle and bone reconstruction, although muscle masses for the manus and pes were calculated as total tendon mass for distal muscles. Convex hull bones (“CHB”) is the convex hull range of masses and the convex hull muscles (“CHM”) is the convex hull range of masses from the muscled reconstructions. The masses for both convex hull methods were calculated from the volumes using only the mean density [893.36 kg m−3 multiplied by 1.206 (Sellers et al., 2012)]. Ratios of each of these estimates are shown in the final four columns on the right side of the table. Dig_Man = digits of the manus, Dig_Pes = digits of the pes.

    Flesh Reconstruction CHB Mean CHM Mean  Flesh/Recon  Recon/CHB  CHM/Recon  Flesh/CHM
Bone mass Muscle mass Total
Humerus 7.47 0.44 3.94 4.38 1.19 7.29 1.71 3.69 1.67 1.02
Ulna/Radius 2.39 0.16 1.40 1.56 0.86 2.25 1.53 1.81 1.44 1.07
Manus 0.55 0.18 0.29 0.47 0.42   1.18 1.12    
Dig_Man 0.44 0.07   0.07 0.29   6.16 0.24    
Femur 10.9 0.62 7.23 7.85 1.50 10.6 1.39 5.23 1.35 1.03
Tibia 2.35 0.53 1.13 1.66 1.28 2.54 1.41 1.30 1.53 0.92
Pes 0.75 0.41 0.27 0.68 0.73   1.10 0.93    
Dig_Pes 0.30 0.13   0.13 0.29   2.31 0.45    

 

TABLE 6. Centre of mass (COM) validation test for extant lion limb segments. “Original COM” was derived from CT scan data for each segment, “CHM COM” from the convex hull models fitted to the muscled limbs, and “Difference” is the “Original COM” minus “CHM COM”. Italicised numbers are long axis lengths from which the percentage (%) of segment lengths were calculated. Positive x, y, and z are anterior, dorsal, and medial, respectively, relative to the origin at the proximal end of the segment. Centre of mass (COM) was expressed as % of length (from the proximal end) relative to the total proximodistal length of the segment. 

  Original COM   CHM COM   Difference Original % of length CHM % of length
x y z   X y z   x y z
Humerus 0.0003 -0.1120 0.005226   -0.0067 -0.1223 0.011691   0.0070 0.0103 -0.0065 45.6 49.8
Ulna/Radius -0.0023 -0.1093 0.001969   0.0016 -0.0935 0.002054   -0.0038 -0.0158 -0.0001 42.7 36.6
Femur -0.0201 -0.0943 -0.0177   -0.0164 -0.1098 -0.0216   -0.0037 0.0154 0.0039 32.1 37.4
Tibia -0.0219 -0.1497 -0.0004   -0.0230 -0.1607 -0.0009   0.0011 0.0111 0.0005 50.3 54.0

 

TABLE 7. Reconstructed and convex hull masses for various segments of the body of Panthera atrox. Bone mass was calculated from estimated bone density (1150 kg m-3) based on relative bone mass (25.7 kg - Table 4) divided by total bone volume (0.0223 m3). Muscle mass was calculated from the muscle and tendon that forms the majority of the segment (e.g., M. biceps brachii has tendons that extend to the scapula and the ulna, but these are all counted to the mass of the humeral segment as that is the majority of the muscle and tendon) (Table 1, Table 2, Table 3), with tendons for the distal muscles being placed in the manus and pes segments. Convex hull bones’ (CHB) and convex hull muscles’ (CHB) masses were calculated from the volumes multiplied by relative density (893.36 kg m−3 multiplied by 1.091, 1.206, and 1.322 (Sellers et al., 2012) respectively). Dig_Man and Dig_Pes are the digits for the manus and pes, respectively. The Recon/CHB is the ratio of reconstructed mass to CHB mass, and CHM/Recon is the ratio of the CHM mass to the reconstructed mass. Rad = radius, Dig_Man = digits of the manus, Fib = fibula, Dig_Pes = digits of the pes.

   Reconstruction   Convex Hull Bones   Convex Hull Muscles Recon/CHB CHM/Recon
Bone Mass Muscle Mass Total   Mean Lower Upper   Mean Lower Upper
Humerus 1.03 7.65 8.88   2.88 2.60 3.15   10.16 9.19 11.14 3.02 1.17
Ulna/Rad 0.73 1.94 2.67   2.03 1.83 2.22   4.44 4.02 4.87 1.32 1.66
Manus 0.34 0.20 0.54   0.92 0.84 1.01   1.28 1.16 1.40 0.59 2.35
Dig_Man 0.17   0.17   0.60 0.55 0.66   0.70 0.63 0.76 0.28 4.12
Femur 1.12 13.5 14.63   2.90 2.62 3.18   17.60 15.92 19.29 5.05 1.20
Tibia/Fib 0.87 1.99 2.86   1.89 1.71 2.07   4.33 3.92 4.75 1.51 1.52
Pes 0.90 0.61 1.50   1.60 1.45 1.76   2.16 1.96 2.37 0.94 1.44
Dig_Pes 0.28   0.28   0.68 0.62 0.75   0.92 0.83 1.01 0.41 3.27

 

TABLE 8. Centre of mass for Panthera atrox limb segments. Positive x, y, and z are anterior, dorsal, and medial, respectively, relative to the origin at the proximal end of the segment. Centre of mass (COM) was expressed as % of length (from the proximal end) relative to the total proximodistal length of the segment.

Segment x y z COM %
of length
Humerus 0.002 -0.119 0.009 0.372
Ulna -0.002 -0.117 0.001 0.360
Manus -0.010 -0.118 -0.001 0.622
Digits -0.015 -0.045 -0.009 0.414
Femur -0.012 -0.144 -0.018 0.380
Tibia -0.017 -0.200 -0.014 0.537
Pes -0.020 -0.114 -0.010 0.464
Digits 0.001 -0.045 -0.017 0.370

 

TABLE 9. Moments of inertia (relative to the centre of mass; Table 8) for the limb segments of Panthera atrox. Units are kg m2.

Humerus   Ulna   Manus   Digits
x y z   x Y z   x y z   x y z
0.1068 0.0616 0.1476   0.0551 0.0081 0.0576   0.0040 0.0015 0.0034   0.0012 0.0007 0.0010
Femur   Tibia   Pes   Digits
x y z   x Y z   x y z   x y z
0.3373 0.1221 0.4066   0.0460 0.0085 0.0482   0.0151 0.0025 0.0150   0.0020 0.0011 0.0015
 

FIGURE 1. CT scan slice showing an approximately mediolateral view (i.e., longitudinal section) of an Asian lion’s forelimb. 1, Dark grey is adipose and connective tissues, lighter grey is muscles, white is bone. Bottom right corner white is a density calibration phantom (1.69 g cm -3; “cortical bone”). 2, Segmentation of the lion forelimb with select muscles highlighted. Abbreviations: FCU - flexor carpi ulnaris; DDF - deep digital flexors; ECR - m. extensor carpi radialis; Pro Quad - m. pronator quadratus; Abd1 - m. abductor digiti I.

figure1

FIGURE 2. Skeletal reconstruction showing the original bones from Panthera atrox and those which have been copied from other vertebrae (red), or from P. leo persica (blue). 1, lateral; 2, dorsal; 3, anterior views. Scale bar is 50 cm.

figure2

FIGURE 3. Muscled reconstruction of Panthera atrox showing the major muscle groups in lateral view. Abbreviations: FCU - m. flexor carpi ulnaris; ECU - m. extensor carpi ulnaris; ECR - m. extensor carpi radialis; EDL - m. extensor digitorum longus. Scale bar is 50 cm.

figure3

FIGURE 4. Convex hull model from the reconstructed Panthera atrox skeleton shown in Figure 2. 1, left lateral view; 2, dorsal view. Scale bar is 50 cm.

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FIGURE 5. Panthera atrox reconstruction showing differences between simple convex hulls and more complex reconstructions. 1, Reconstructed muscles overlaid on the convex hull of just the bones. Any muscles that are visible extend beyond the range of the convex hull, thereby demonstrating the underestimation of size by convex hulls based solely on bones. 2, Reconstructions showing the posteroventral movement of the centre of mass (COM) between the bone convex hull and the muscled convex hull models of Panthera atrox. Scale bar is 50 cm.

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author1Andrew R. Cuff. Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, United Kingdom; Structure and Motion Lab, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts, AL9 7TA, United Kingdom. This email address is being protected from spambots. You need JavaScript enabled to view it.

Andrew R. Cuff holds a PhD from the University of Bristol and is currently a postdoctoral researcher at The Royal Veterinary College. He works as a biomechanist, looking at locomotion and feeding across a wide range of vertebrates but with particular interest in archosaurs. This research combines modern anatomical studies and dissections with experiments and computer models and simulations to test subject specific and broad evolutionary hypotheses.

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author2Anjali Goswami. Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, United Kingdom. This email address is being protected from spambots. You need JavaScript enabled to view it.

Anjali Goswami is Professor of Palaeobiology at University College London, jointly appointed in the Department of Genetics, Evolution & Environment and the Department of Earth Sciences. She is also a scientific associate of the Natural History Museum, London, and co-director of the London Centre for Ecology and Evolution. She is a vertebrate palaeobiologist, specialising in mammalian macroevolution, evolutionary development, and quantitative approaches to palaeobiology, particularly in using 3-D morphometrics to reconstruct morphological and developmental evolution across large scales.


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author3John R. Hutchinson. Structure and Motion Lab, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts, AL9 7TA, United Kingdom; Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, United Kingdom. This email address is being protected from spambots. You need JavaScript enabled to view it.

Dr. John R. Hutchinson is a Professor of Evolutionary Biomechanics at The Royal Veterinary College in the University of London, United Kingdom. His team studies how the musculoskeletal system has evolved to produce major changes in form, function, development and behavior. In particular, they study how body size change require changes in locomotor function and how great transformations in locomotor abilities were achieved. To do this, they integrate data from anatomical dissection and histology, 3D imaging, computer modelling and simulation, biomechanical experiments, phylogenetics and other methods, applied to extinct and extant taxa. A major focus of those methods is on testing the validity of quantitative computational models and the influence of assumptions on the conclusions drawn from them.