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Megalosaurus = Torvosaurus -- supplementary data for Mr. Mortimer



     Using abelisaurs, Ceratosaurus, Dilophosaurus/Syntarsus (I'm aware of the new name for the latter, but let's leave it aside for the moment; perhaps I should write here "dilophosaurs", or dilophosaur forms), Coelophysis, Herrerasaurus, as successively more removed outgroups, Megalosaurus is Tetanurae in Megalosauridae with a round, pronounced accessory antorbital fenestra; pleurocoelous cervicals; bowed humerus; ascending process of astragalus greater than 1/6 length of epipodium.
      Based upon the hypodigm of this genus, Megalosaurus has the following combination of characters: dentary rugosae parallel-sided, separate, with peaked summits, about as high as wide; teeth moderately spaced, tooth interval:tooth row index 9.3; cranial cervicals with very elongate epipophysis, centra pleurocoelous (reversed in Megalosaurus tanneri); caudal dorsals with rounded ends, H:L index 88, spine long, low thin; 5 fused sacrals with rounded ends, ribs present, parapophyses large and blunt; scapula with moderately narrow blade having cranial convexity and caudal concavity, cranial projection level with glenoid crest; coracoid long and low, smoothly rounded, with stout pre- and sub-glenoid bosses, no caudal hook; humerus bowed (reversed in Megalosaurus tanneri), medial tuberosity strong, pronounced and heavy medial trochanter, strong deltoid crest arise below caput and extending over 50% down shaft; ulna extraord! ! inarily stout; ilium long and low, anterior blade separate from pubic peduncle by open pubic notch; posterior blade pointed and extending beyond spine, spine originating well above posterior blade and higher caudally so that its caudoventral corner is well below posterior blade, pubic peduncle massive, acetabular crest continous onto ischial peduncle and widely separate from spine, ischial notch wide, ischial peduncle heavy and rounded; pubis with obturator notch only, very slight distal expansion; femur with caput 40 degrees to distal end, shaftly strongly curved cranially, capitulum with ventral notch set off by vertical grooves from greater trochanter which is slightly lower, anteiror trochanter a stout conical process without a trochanteric shelf, 4th trochanter on caudomedial edge of shaft and may be very large, distal condyles widely separate caudally, ectocondyle with stout tuberous process extending above and far in front of caput, deep popliteal notch, caput surface d! ! ipping laterally, caudal condyles overhanging shaft, fibular flange stout, distal end moderately expanded and its lateral 2/3 ventrally arched, astragalar sulcus deep, its upper shelf dipping 45 degrees medially; fibula with medially concave caput and distal vertical medial ridge; metatarsal II with distal end transversely convex and rounding up far up front of shaft, lateral edge of shaft convex above ligamentary pit, distal end reduced caudally, condyle narrow and simple; metatarsal III distal condyle with medial ridge having flanking concavities.
      Megalosaurus phillipsi, Jurassic, Kimmeridgian Clay, Swindon, Wiltshire, England. Type: OUM J29886, right tibia (first illustrated by von Huene in 1926). From the same individual is an associated set of left metatarsals II-IV, OUM J13586, first illustrated by John Phillips in 1971. von Huene stated both specimens were from the Stonesfield Bathonian, but an annotated copy of von Huene's paper at OUM, in the hand of W.J. Sollas states von Huene is in error, both specimens from Swindon, Wiltshire. Megalosaurus phillipsi can be defined a combination of character states plesiomorphic at more restrictive (further derived) levels, and synapomorphic compared to more general (primitive) levels (Padian 1986). Megalosaurus with very massive tibia and metatarsus. Compared with Megalosaurus bucklandii, M. phillipsi has a tibia with more expanded head, the shaft straighter and more massive; the fibular flange begins higher! ! on the shaft and extends farther down; if this is oriented laterally, then the head is rotated much more craniolaterally, its axis 55 degrees versus 40 degrees; the astragalar facet lacks the dorosal pit, but has the same curvature of the overhang; the concavity of the distal end is wider; the postfibular plate does not extend so far below the medial end.
      Megalosaurus bucklandii. Jurassic, Bathonian, Great Oolite Group, Taynton Limestone Formation ("Stonesfield Member"), Oxfordshire; White Limestone of Enslow Bridge, near Oxford (OUM J29765, right scapula). The lectotype is OUM J13505 (cast BMNBH 2301), rostral right dentary. The "kleptotype" (i.e., from the same individual) is: OUM J13577, last dorsal; J13576, sacrum; J13579, proximal caudal; J13565, left ischium; J13561, right femur; J13572, left metatarsal II. The complete hypodigm (museum #s not listed here) consists of: 2 maxillae; left jugal; 3 partial mandibles (1 lost); 1 cervical; 3 dorsals; 3 sacrums; 2 caudals; 6 pectoral girdles (variably complete); 2 humeri; 1 ulna; 6 ilia (variably complete); 3 pubis (none complete); 2 ischia; 12 femora (4 lost, all variably eroded); 6 tibiae (variably complete, 1 lost); 2 metatarsals; lost pedal ungual; pedal phalanx. A Megalosaurus with with 11 teeth in 292 mm of the ! ! rostral part of the dentary; teeth 27 mm between centers, jaw 83 mm deep behind alveolus 5; tooth interval: depth of jaw index 32; rugosae widely separate to their bases, subrectangular, with peaked summits; jaw shallow slightly behind alveoli 6 and 7, deepending caudally; chin slants upward from below alveolus 3, with rounded tip confined to upper half; rostrodorsal tip notched into alveolus 1; splenial groove opens below front of alveolus 10; lingual bar very high and flat; teeth slender, not greatly recurved, with distal border convex at base of enamel, labial and lingual faces slightly concave mesiodistally at base; mesiolateral surface bulges outward and mesial serrated region becomes increasingly internal toward front of the jaw; serrations on upper 1/3 of mesial edge and entire distal edge, 9-10 serrations per 5 mm; mesial edge thicker and more smoothly convex than distal edge.
      Metriacanthosaurus: Megalosauridae with short, massive pectorals having low spines similar to Allosaurus whitei AMNH 666 Pickering 1996, reaching 3.5 times centra height, hyposphene widening ventrally; caudal dorsals and sacrals wide; caudals high and compressed; ilium + ischium fused; pubis with foot; femur slender, caput well set off from head by caudal vertical groove; anterior trochanter proximal and thick, shaft with abrupt vertical end; tibia with very large tuberosity extending far cranioproximally, its cranial edge straight.
      Metriacanthosaurus reynoldsi. Jurassic, Bathonian, Great Oolite Group, Charlbury Formation ("Hook Norton Member"). The lectotype is SDM 44.19, right ilium (first illustrated by S. Reynolds 1939, fig. 8). Referred specimens (all at SDM, BMNH, OUM, GSM, #s not listed here): maxillae, dentaries, cervical, 3 dorsals, 3 sacrums, 9 caudals, three right scapulae (2 incomplete), 2 right coracoids, 2 left humeri, right ischium, 2 partial left ischia, right femur, left and right metatarsa III. Megalosauridae with sacral 4 longer ventrally than dorsally. The hypodigm indicates a Metriacanthosaurus with an ilium having a more horizontal crest; the anterior blade is lower; the posterior blade is lower, but begins much higher above the base of the peduncle, with a much greater area exposed below the spine; the pubic peduncle is longer; the ischial peduncle is much longer, the notch more open.
      Metriacanthosaurus brevis. Jurassic, Bathonian, Great Oolite Group, Taynton Limestone Formation, Stonesfield. The type is BMNH 31811, left ilium. This was first described in 1857 (repeated in 1884) by Richard Owen, but his accompanying plates are not 31811 but BMNH R1100 Megalosaurus bucklandii. Referred specimens; OUM J29888, right pectoral girdle; BMNH 31806, right femur; BMNH 31809, left tibia; OUM J13562, right tibia. Metriacanthosaurus differing from Metriacanthosaurus parkeri in having an ilium with a nearly straight crest; the ilium is higher, the anterior blade much higher, 250 vs. 200 mm; the posterior blade is more nearly horizontal; the pubic peduncle dips less steeply cranially so that the cranial notch is narrower; the acetabulum is longer and longer, but shallower, its crest ending farther forward. The two are different, but their great height and shortness -- diagnostic for Metriacant! ! hosaurus in Megalosauridae -- separates them clearly from ilia of Megalosaurus spp., Allosaurus fragilis, Allosaurus whitei.
      Eustreptospondylus oxoniensis. Jurassic, Callovian, Oxford Clay Formation (Stewartby Member). OUM J13558, although subadult, lacks the trochanteric shelf and fibular sulcus diagnostic of Ceratosauria. Megalosauridae with premaxilla about as long as high; Pm 4 / M 9 / D 13; maxilla with wide dorsal process having a large, imperforate vacuity and maxillary recess; rugosae large, squarish, separate; frontal with small supraorbital notch and depressed area rostral to supratemporal fenestra; parietals form a flat, narrow table, squamosals reach quadratojugal without ventral expansion; lower tip of opithotic at level of middle of condyle; foramen magnum as wide as condyle; dentary with very low, separate rugosae; 13 alveoli in 215 mm; 10 cervicals, 3 pectorals, 8 dorsals, 5 sacrals, ca. 50 caudals; strape-like scapular blade; humerus with weak deltoid crest; ilium with short pubic peduncle, wide and shallow cranial notch, no caudal not! ! ch, posterior blade well below a weak spine, spine terminating rostrodorsal to blade; pubis with high obturator notch, no foramen, shaft straight, short distal foot; ischium slightly downcurved; femur with prounced but low anterior trochanter, no trochanteric shelf, weakly developed ento- and ectocondyles, ectocondyle with narrow tuber, tibia with moderate tuberosity, inward-dipping, subequal condyles, sharp and low fibular flange; astragalus with wide, low dorsal process; metatarsals slender, central metatarsus relatively compressed.