Early Bathonian, Middle Jurassic
Chipping Norton Limestone Formation, England
Material- ?(BMNH R9679) sacrum
?(BMNH R9680) sacrum
?(GSM 37523) dorsal vertebra
?(OUM J.13720) proximal caudal vertebra
?(OUM J.29799) proximal caudal vertebra
?(SDM 44.7) distal caudal vertebra
?(SDM 44.10) dorsal vertebra
?(SDM 44.16) proximal scapula (Reynolds, 1939)
?(SDM 44.17) proximal scapula (Reynolds, 1939)
(SDM 44.19; intended holotype) ilium (Reynolds, 1939)
?(SDM 44.22) humerus
? tooth (Reynolds, 1939)
Diagnosis- (suggested) several pronounced vertical ridges above the supracetabular shelf extending halfway to the blade's dorsal edge.
Other diagnoses- Pickering (DML, 2002) listed several features as differing from Metriacanthosaurus parkeri. Of these, the straighter dorsal ilial margin and broadly exposed medial wall of the brevis shelf are seen in Eustreptospondylus, while the long ischial peduncle is also present in "Szechuanosaurus" zigongensis. The lower ilial blade are seen in both. Contra Pickering, the pubic peduncle is not noticably longer nor the subpreacetabular notch more open than in Metriacanthosaurus.
Comments- Lydekker (1888) referred a metatarsal III (BMNH R413) from the Chipping Norton Formation to Megalosaurus bucklandi. Gardiner (1937, 1938) and Reynolds (1938) reported large theropod remains from two quarries in the Chipping Norton Limestone Formation, which Reynolds (1939) described and referred to Megalosaurus. Pickering (1995) credited the name Metriacanthosaurus reynoldsi to Welles, Powell and Pickering in his 1995 unpublished bibliographic manuscript. It was later used in the comparative section of another unpublished manuscript (Welles and Pickering, 1999). This paper was largely extracted from the European megalosaur manuscript Welles and Powell worked on in the 1970s but never published, specifically the Megalosaurus redescription section. Pickering intends to publish an updated version of the megalosaur manuscript as Mutanda Dinosaurologica, and has posted small excerpts including the diagnosis of Metriacanthosaurus "reynoldsi" online (DML, 2002). In any case, the name is a nomen nudum as Pickering didn't follow ICZN Article 7 Recommendation 7a, Article 8a or Recommendation 8A. The 1999 paper shows his new taxon to be based on all the Chipping Norton theropod material from both quarries, as well as BMNH R413, scapula OUM J.29800 and a few other elements. Day and Barrett (2004) believed both their Megalosaurus femoral morphotypes A and B were present in the sample- SDM 44.23 (Q in the figure below) as morphotype B and SDM 44.24 as morphotype A. Benson (2009, 2010) referred the New Park Quarry material to Megalosaurus bucklandii based on the close resemblence of maxilla SDM 44.1 (A) to Taynton Limestone specimens and an M. bucklandii autapomorphy in sacrum SDM 44.4 (G), while other elements were provisionally referred as there is no evidence of more than one taxon in the quarry. These additional elements are- maxilla BMNH R8303 (B), anterior dentary BMNH R8304 (D), partial dentary BMNH R8305 (C), proximal ischium BMNH R9668, proximal caudal vertebrae BMNH R9672-9673 (H), partial anterior cervical vertebra BMNH R9674 (E), mid caudal vertebrae BMNH R9675-9676 (J, K?), proximal caudal vertebra BMNH R9677 (I), mid caudal vertebra SDM 44.5 (L), coracoids SDM 44.14-15 (M), humerus SDM 44.18 (N), femur SDM 44.24 (P) and distal metatarsal IV 44.25. BMNH R413 and OUM J.29800 were also referred to M. bucklandii based on autapomorphies. Finally, Benson (2010) referred two specimens from Oakham Quarry to M. bucklandii based on autapomorphies (ischium SDM 44.20 [O] and metatarsal III BMNH R9665 [R]), but refrained from referring additional elements from this quarry as he notes some "can be referred to a second, unnamed taxon (R. B. J. Benson, unpubl. data)." This near certainly refers to "reynoldsi", whose intended holotype is an ilium from Oakham Quarry (SDM 44.19). Further study by Benson and/or Pickering may clarify the identity of the other Oakham Quarry elements. The material Welles and Pickering referred to "reynoldsi" is here provisionally retained in the species, as none has been usefully described in the published literature.
The identity of SDM 44.19 is difficult to determine from the published illustration, since many useful ilial characters would only be visible in medial or ventral views. However, it is a tetanurine based on the lack of a strong crest between the supracetabular crest and brevis fossa, and is not a coelurosaur based on the large ischial peduncle and widely exposed brevis fossa in lateral view. It differs from Megalosaurus and Metriacanthosaurus in many of the same ways- anteroposteriorly narrow pubic peduncle; broad medial wall to the acetabulum, especially posteriorly; longer ischial peduncle; broad esposure of medial wall of the brevis fossa; low ilial blade. It is more similar to Metriacanthosaurus in the wide subpreacetabular notch, and anteroposteriorly wide ischial peduncle, but shares a series of short vertical ridges above the acetabulum with Megalosaurus (albeit more pronounced). Pickering's (DML, 2002) only ilial character for Metriacanthosaurus is "ilium + ischium fused", which isn't true of M. parkeri or "reynoldsi." Thus is seems whatever "reynoldsi" is, there's no reason to refer it to Metriacanthosaurus. A greater resemblence is seen to Eustreptospondylus, which shares the narrow pubic peduncle, broad esposure of medial wall of the brevis fossa, and low ilial blade. Another similar ilium is that of "Szechuanosaurus" zigongensis, which shares the broad medial wall to the acetabulum, longer ischial peduncle, and low ilial blade. Which of these two taxa it is more closely related to will require study of the specimen itself and additional specimens from Oakham Quarry. For now it is best placed either in basal Tetanurae or Eustreptospondylinae.
The illustrated Oakham tooth (BMNH or SDM colls) is short (height/FABL 1.66) and moderately recuved with perpendicular serrations on at least the apical half of the distal carina. Only light longitudinal striations are indicated on the enamel. At least one of the scapulae (SDM 44.16 and 44.17) is unfused to the coracoid, though it is unknown if these were from Oakham Quarry, or merely from New Park Quarry and unreferred by Benson to Megalosaurus.
References- Lydekker, 1888. Catalogue of the Fossil Reptilia and Amphibia in the British Museum (Natural History), Cromwell Road, S.W., Part 1. Containing the Orders Ornithosauria, Crocodilia, Dinosauria, Squamata, Rhynchocephalia, and Proterosauria. British Museum of Natural History, London. 309pp.
Gardiner, 1937. Reptile-bearing oolite, Stow. Reports of the British Association for the Advancement of Science (Blackpool). 1936, 296.
Gardiner, 1938. Reptile-bearing oolite, Stow. Reports of the British Association for the Advancement of Science (Nottingham). 1937, 290.
Reynolds, 1938. A collection of reptilian bones from the Oölite near Stow-in-the-Wold, Glos. Reports of the British Association for the Advancement of Science. 1937, 356-357.
Reynolds, 1939. A collection of reptile bones from the Oolite near Stow-on-the-Wold, Gloucestershire. Geological Magazine. 76, 193-214.
Pickering, 1995. Jurassic Park: Unauthorized Jewish Fractals in Philopatry. A Fractal Scaling in Dinosaurology Project, 2nd revised printing. Capitola, California. 478 pp.
Welles and Pickering, 1999. Megalosaurus bucklandii. Private publication of Stephen Pickering, An extract from Archosauromorpha: Cladistics & Osteologies. A Fractal Scaling in Dinosaurology Project. 119 pp.
Day and Barrett, 2004. Material Referred to Megalosaurus (Dinosauria: Theropoda) from the Middle Jurassic of Stonesfield, Oxfordshire, England: one taxon or two? Proceedings of the Geologists' Association. 115, 359-366.
Benson, 2009. An assessment of variability in theropod dinosaur remains from the Bathonian (Middle Jurassic) of Stonesfield and New Park Quarry, UK and taxonomic implications for Megalosaurus bucklandii and Iliosuchus incognitus. Palaeontology. 52(4), 857-877.
Benson, 2010. A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods. Zoological Journal of the Linnean Society. DOI 10.1111/j.1096-3642.2009.00569.x
Pickering, in prep. Mutanda Dinosaurologica.