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Figure 7. A in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 7. A, dorsal view of m. biventer cervicis (m. biv. c., dark outline) and m. longus colli dorsalis pars cranialis of Aquila chrysaetos. Note the tendon intervening between anterior and posterior bellies of m. biv. c. M. complexus has been removed. B, dorsal view of m. transversospinalis capitis (m. trans. cap., dark outline) of Alligator mississippiensis. Medial and lateral portions of m. trans. cap. in Alligator are not distinguished here. C, lateral view of m. trans. cap. of Alligator mississippiensis (dark outline). D, m. complexus (dark outline) and m. rectus capitis lateralis (light outline) of Pelicanus occidentalis in lateral view. E, m. complexus of Pelicanus occidentalis, outlined in dark grey on the right. This is a dorsal view, with anterior towards the top. F, dorsal view of dissected Alligator mississippiensis, with m. epistrpheo-capitis lateralis, m. spinocapitis posticus and m. transversospinalis cervicis outlined in grey. M. transversospinalis capitis has been removed. G, m. splenius capitis of Anas platyrhynchos, from C2 to the occiput, outlined in grey, in posterior view. M. complexus and m. biventer cervicis have been removed. H, m. epistropheo-capitis medialis/m. altoïdius capitis of Caiman crocodylus, outlined in grey. M. transversospinalis capitis and m. epistropheo-capitis lateralis have been removed.

Figure 6 in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 6. Neck muscle origins and insertions in crocodilians. A, muscle attachments on C1–C9 of Caiman crocodylus. B, muscle insertions on the occiput of Caiman crocodylus. m. trans. cap., m. transversospinalis capitis; m. epi.-cap. lat., m. epstropheo-capitis lateralis; m. epi.-cap. med., m. epstropheo-capitis medialis; m. sp.cap. post., m. spinocapitis posticus; m. trans. cerv., m. transversospinalis cervicis; m. long. cerv., m. longissimus cervicis (m. articulares/m. tendinoarticulares); m. long. cap., m. longus capitis; m. long. cap. sup., m. longissimus capitis superficialis; m. long. cap. prof., m. longissimus capitis profundus; m. il. cap., m. iliocostalis capitis; m. il. cerv., m. iliocostalis cervicis.

Figure 21. A in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 21. A, origin scars of m. longissimus capitis superficialis (C7–D1 parapophyses) and m. longissimus capitis profundus (C6–C3 parapophyses) of Tyrannosaurus rex (AMNH 5027). B, short moment arm of m. longissimus capitis superficialis for neck plus head dorsiflexion. C, paroccipital process insertions and moment arms of m. longissimus capitis superficialis on Daspletosaurus torosus (CMN 8506). D, basioccipital insertions and moment arms of m. longissimus capitis profundus on Daspletosaurus torosus (CMN 8506; the specimen is incomplete and the images are partly mirrored).

Figure 12. A in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 12. A, origins of m. rectus capitis lateralis (m. r.c.l.) and rectus capitis ventralis (m. r.c.v.) of Corvus brachyrhynchos, from C2 prosessus ventralis. B, all origins of m. r.c.v. from anterior cervicals of another specimen of Corvus brachyrhynchos, and its m. rectus capitis lateralis origin from C2. Both images are ventrolateral views. C, ventrolateral view of m. rectus capitis ventralis (with light outline) of Falco columbarius.

Figure 17. A in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 17. A, topological appearance of m. transversospinalis capitis on anterior vertebrae and skull of Tyrannosaurus rex (AMNH 5027). The insertion is inferred as strongly tendinous, and is rendered as white. B, topological appearance of m. longissimus capitis superficialis restored on the same skeleton. The posterior origin was tendinous, and its morphology is depicted as white. C, D, topological appearance of (C) m. complexus and (D) m. iliocostalis capitis on anterior axial skeleton of Tyrannosaurus rex skeleton (AMNH 5027). A′–D′, functional inference strengths of muscles after visualization of inference space in Figure 2. A′, strength of functional inference for m. transversospinalis capitis (m. trans. cap. strong Level I′ inference of dorsiflexion). B′, weaker, Level II′ inference of lateroflexion in m. longissimus capitis superficialis. C′, D′, Level II′ strengths of functional inference for m. complexus (m. compl.) and m. iliocostalis capitis (m. il. cap.).

Figure 3 in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 3. Flow chart for extant behavioural interpolation, which enables inference of muscle-modulated behaviours in extinct animals. The certainty of behavioural inference in an extinct taxon is inversely related to the behaviour's specificity. Behaviour can be inferred by phylogenetic bracketing if similarity of muscle function is established in extant clades by kinematic and physiological considerations, and if these functions correlate with similar behaviours in the extant groups.

Figure 11. A in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 11. A, origins (dark shapes) and insertions (lighter outlined shapes) of mm. intertransversarii aponeuroses on posterior cervical vertebrae of Struthio camelus. Origins are from anterior faces of lateral tubercles, and insertions are onto posterior projections of the lateral tubercles. Arrows represent lines of action whereby insertions are drawn towards the origins to effect intervertebral lateroflexion. B, origins (dark) and insertions (lighter) of mm. inclusii on posterior cervical vertebrae of Struthio camelus. Origins are from anterior faces of the costal processes, and insertions are onto the lateral and dorsolateral tubercles. Arrows represent lines of action whereby insertions are drawn towards the origins. C, origins (dark-filled shapes) and insertions (light-filled shapes) of lateral portions of mm. intertransversarii in Caiman crocodylus. Arrows represent lines of action from origin to insertion, by which the muscles would lateroflex the anterior vertebra of each pair relative to the posterior one.

Figure 20. A in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 20. A, origin scar of m. splenius capitis from C2 of Tyrannosaurus rex (BHI 3033), in anterodorsal view. B, area of possible insertions of m. splenius capitis (medial part) on the occiput of Daspletosaurus torosus (CMN 8506; the specimen is incomplete and the image partly mirrored), with moment arms shown for dorsiflexion and lateroflexion. C, insertions of m. longus colli dorsalis/m. transversospinalis cervicis onto posterior and dorsal surfaces of epipophyses, from C2 to C5. The most prominent insertion is a posteriorly concave scar on the C2 epipophysis. D, centres of rotation (white circles) and moment arms (lines) for insertions of m. longus colli dorsalis/m. transversospinalis cervicis, on cervical vertebrae of Tyrannosaurus rex (BHI 3033). Centres of rotation are estimated to be at positions similar to those Selbie, Thomson & Richmond (1993) determined for intervertebral flexion in cats.

Figure 19. A in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 19. A, origins of m. transversospinalis capitis (C2–C9), m. complexus (C2–C5) and m. splenius capitis from C2 and possibly C3, of Tyrannosaurus rex (BHI 3033). B, rugose scarring of m. transversospinalis capitis insertion on parietals of Tyrannosaurus rex (AMNH 5029). C, insertion of m. transversospinalis capitis onto parietals of Daspletosaurus torosus (CMN 8506; the specimen is incomplete and the image partly mirrored), with moment arms for lateral and dorsiflexion. D, insertions and moment arms for m. complexus (two dorsal) and m. iliocostalis capitis (ventral) on occiput of Daspletosaurus torosus (CMN 8506; the specimen is incomplete and the image partly mirrored for clarity).

Figure 16 in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 16. Schematic diagram of major neck muscles of Tyrannosaurus rex in dorsal view. A–C represent successively deeper layers, and other conventions are as in Figure 15. M. complexus inserts dorsally on the squamosal, and m. iliocostalis capitis inserts along the ventral edge of the paroccipital process. M. longissimus capitis superficialis inserts between these on the lateral edge of the paroccipital process. In C a probable lateral part of m. spinalis capitis is signified by a '? ' .

Figure 18 in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 18. Topological appearance of (A) m. splenius capitis (medial part) and (B) m. longus colli dorsalis/ transversospinalis cervicis, on anterior vertebrae and skull of Tyrannosaurus rex skeleton (AMNH 5027). Note that the parietals are probably closer to the axial neural spine than in neutral life posture, and m. splenius capitis would be longer than shown here. C, topological appearance of m. splenius on another specimen of Tyrannosaurus rex (BHI 3033). M. complexus is also represented, and m. transversospinalis capits is depicted as though reflected back. D, E, appearance of m. longissimus capitis profundus (large anterior muscle), and cervical mm. intertransversarii (bands between transverse processes), on skeleton of Tyrannosaurus rex (AMNH 5027). A′–E′, functional inference strengths of muscles after visualization of inference space in Figure 2. A′, strength of functional inference for m. splenius capitis of tyrannosaurids, for head dorsiflexion and stabilization. The large inference space is possible by morphological and physiological bracketing between homologous muscles in birds and crocodilians. B′, strength of functional inference for m. transversospinalis cervicis of tyrannosaurids, for neck dorsiflexion. Inference strengh is particularly high for this muscle. D′, Level II′ inference for ventroflexion by m. longissimus capitis profundus. E′, inferernce for lateroflexion by mm. interntransversarii, with poor, Level III′ support from physiological data; EMG has been uninformative about mm. intertrans. lateroflexion in extant archosaurs .

Figure 23. A in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 23. A, topological appearance of m. rectus capitis ventralis (anterior muscles) and m. iliocostalis cervicis (posteroventrally originating muscles) on anterior axial skeleton of Tyrannosaurus rex (BHI 3033), ventral view. The moment arm for lateral flexion by m. iliocostalis cervicis is superimposed. B, m. r.c.v.: origins of m. rectus capitis ventralis from ventral spinous processes of Tyrannosaurus rex (BHI 3033) with arrow showing course of the muscle. m. il. cerv.: origin from ventral centra and insertions onto ventral fascia of cervical ribs of m. iliocostalis cervicis, with arrow showing course of the muscle. C, insertion of m. rectus capitis ventralis onto basioccipital of Daspletosaurus torosus (CMN 8506; the specimen is incomplete and the image partly mirrored), showing moment arms. Because the tyrannosaurid occiput slopes anteroventrally, the ventroflexion moment arm is somewhat longer than depicted in this view. D, strength of functional inference for head ventroflexion by m. rectus capitis ventralis in Tyrannosaurus rex. E, strength of functional inference for neck lateroflexion by m. iliocostalis cervicis of Tyrannosaurus rex.

Figure 19 in Diversity of late Maastrichtian Tyrannosauridae (Dinosauria: Theropoda) from western North America

Figure 19. Diagram of the results of a quantitative reconstruction of a growth series of five Tyrannosaurus rex specimens.

Figure 8 in Diversity of late Maastrichtian Tyrannosauridae (Dinosauria: Theropoda) from western North America

Figure 8. Comparison of the dorsal skull roof of LACM 28345 with other tyrannosaurids. AMNH 5027 modified after Osborn (1912) and CMN 8506 modified after Russell (1970).

Figure 13 in Diversity of late Maastrichtian Tyrannosauridae (Dinosauria: Theropoda) from western North America

Figure 13. Comparison of the surangular of LACM 23845 with other tyrannosaurids in left lateral view. AMNH 5027 modified after Osborn (1912) and CMN 8506 after Russell (1970).

Figure 12 in Diversity of late Maastrichtian Tyrannosauridae (Dinosauria: Theropoda) from western North America

Figure 12. Comparison of the quadratojugal of LACM 23845 with other tyrannosaurids in left lateral view. AMNH 5027 modified after Osborn (1912) and PIN 551–2 after Maleev (1974).

Figure 9. A in Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

Figure 9. A, insertions of (dark grey) m. longus colli dorsalis pars cranialis onto anterior cervical epipophyses of Haliaeetus leucocephalus. B, schematic origin (light grey) of m. longus colli dorsalis pars cranialis, from cervicodorsal region of Struthio camelus. C, schematic origins (dark grey) of m. longus colli dorsalis pars cranialis from epipophyses (processes dorsales) of posterior cervicals in Struthio camelus. Slips from these origins coalasce with the main belly of the muscle, as demarcated by the light-shaded lines. The main belly of the muscle continues dorsally. D, schematic origin and insertions of m. longus colli dorsalis pars caudalis. This muscle subsystem originates from the cervicodorsal region and sends multiple bellies to insert on posterior cervical epipophyses. E, origins of m. longissimus cervicis/m interarticulares of Caiman crocodylus. The gradient-filled slips represent association of origins with the fascia surrounding the muscles. F, anteriormost insertions (dark grey) of m. longissimus cervicis/m. interarticulares, and m. transversospinalis cervicis, of Caiman crocodylus.

opencc-zeroJun 2022View details →

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Supporting CT Data for: Two exceptionally preserved juvenile specimens of Gorgosaurus libratus (Tyrannosauridae, Albertosaurinae) provide new insight into the timing of ontogenetic changes in tyrannosaurids

Known from dozens of specimens discovered since the early 20th century, Gorgosaurus libratus has arguably contributed more than any other taxon to our understanding of the life history of tyrannosaurids. However, juvenile material for this taxon is rare. Here, we describe two small, articulated Gorgosaurus specimens (skull lengths of ~500 mm) that help advance our knowledge of the anatomy and ontogeny of this taxon and of tyrannosaurids in general. The new specimens exhibit hallmark juvenile tyrannosaurid features, including long, low, and narrow skulls, large circular orbits, absent or incipient cranial ornamentation, ziphodont dentition, and an overall gracile skull frame. Comparison with other Gorgosaurus specimens of various ontogenetic stages allows for an examination of the timing of morphological changes that occurred through ontogeny in this taxon relative to other tyrannosaurids. Of particular note, Gorgosaurus and the larger Tyrannosaurus rex are found to have experienced similar ontogenetic transformations at similar percent skull length relative to the large known individuals for each respective taxon but at different absolute body sizes and biological ages, occurring at a larger size and older age in T. rex than in Gorgosaurus. These results suggest a dissociation between the timing of cranial development and body size in tyrannosaurids. Finally, the recognition of ontogenetically invariant characters in Gorgosaurus makes it possible to determine the taxonomic identity of previously misidentified specimens.

opennotspecifiedDec 2001View details →

Figure 7.2 in The phylogeny and taxonomy of the Tyrannosauridae

Figure 7.2. Phylogeny of Tyrannosauridae, Solid lines represent the strict consensus of the fifteen most palsimonious tree s ex cludin g Siamotyrannus and Shanshanosaur,,s,s (tree metrics including all autapomorphic characters: TL L50, cI 0.860, Rt 0.761, RC 0.655, H! 0.1o0: if autapomorphic characters are excluded, TL 125, cl 0,833, RI 0.761, RC 0.634, Hl 0.273). Dashed lines indicate position of Siamotyrannus and Shanshanosaurus wh en included (tree metrics including autapomorphic cbaracters: TL 152, CI 0.8J-r, RI 0.768, RC 0.657, Hr 0.164).