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Volume 27.1
January–April 2024
Full table of contents
ISSN: 1094-8074, web version;
1935-3952, print version
Recent Research Articles
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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 |
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.
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.
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.
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.
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.
Andrew 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. acuff@rvc.ac.uk
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.
Anjali Goswami. Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, United Kingdom. a.goswami@ucl.ac.uk
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.
John 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. jhutchinson@rvc.ac.uk
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.
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 |
Reconstruction of the musculoskeletal system in an extinct lion
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
Reconstitution du système musculosquelettique d’un lion éteint
Panthera atrox est un lion éteint du Pléistocène d’Amérique du Nord. C’était un des plus grands félidés qui ait jamais existé. Les reconstitutions précédentes se sont toujours basées sur des spécimens composites, et aucun spécimen connu ne préserve de tissus mous. Nous présentons dans cet article une reconstitution du spécimen le plus complet de P. atrox jamais découvert, à partir duquel nous calculons des paramètres biologiques clés, notamment la masse corporelle. En utilisant les équations de mise à l’échelle précédemment publiées, nous estimons la taille de la musculature des membres et de la colonne vertébrale. Les muscles d’un lion actuel ont été mis à l’échelle aux tailles attendues et placés sur le squelette. Le corps et les membres ont été reconstitués numériquement (en utilisant une méthode d’enveloppe convexe) à partir du squelette avant que cette méthode soit répétée avec les segments des membres avec les muscles. D’après la répétition de cette approche sur un lion actuel, nos résultats montrent que les reconstitutions en enveloppe convexe des muscles et os combinés sont les plus précises pour reproduire les dimensions des membres, notamment les centres de masse, des grands félidés. Il est également possible, d’après les reconstitutions, d’estimer la composition corporelle de P. atrox, ce qui permet la reconstitution la plus complète des tissus mous de cette espèce éteinte, notamment les propriétés biomécaniques des membres.
Mots-clés : reconstitution fossile ; muscles ; Felidae ; Panthera atrox ; mise à l’échelle
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
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Review: The Princeton Field Guide to Mesozoic Sea Reptiles
The Princeton Field Guide to Mesozoic Sea Reptiles
Article number: 26.1.1R
April 2023 -