Friday, April 9, 2010

Pickering's taxa 3: Metriacanthosaurus reynoldsi

"Metriacanthosaurus" "reynoldsi" Welles, Powell and Pickering vide Pickering, 1995
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 Pickering (1995) credited the name Metriacanthosaurus reynoldsi to Welles, Powell and Pickering in his 1995 unpublished bibliographic manuscript. It was later used in the comparative section of another unpublished manuscript (Welles and Pickering, 1999).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.


Megalosaurus bucklandii material referred to "Metriacanthosaurus" "reynoldsi" by Welles and Pickering (1999).  Not to scale.  For specimen numbers, see list above.  Taken from Benson (2010), except F, K and M from Reynolds (1939) and P and Q from Benson (2009).

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.


Ilia compared in right lateral view- A. Megalosaurus bucklandii (after Benson, 2010). B. Metriacanthosaurus parkeri (modified from Walker, 1964). C. "Metriacanthosaurus" "reynoldsi" (modified from Reynolds, 1939). D. Eustreptospondylus (after Sadlier et al., 2008). E. "Szechuanosaurus" zigongensis (modified after Gao, 1993).

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 O├Âlite 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.

9 comments:

  1. Stephan PickeringApril 9, 2010 at 3:07 PM

    Metriacanthosaurus reynoldsi

    Jurassic, Bathonian, Great Oolite Group, Charlbury Formation [= 'Hook Norton Member, P. (Parkinsonia) convergens subzone]; Oakham Quarry, near Little Compton; New Park Quarry & Longborough Road Quarry, near Stow-on-the-Wold; unnamed limestone quarry near Moreton-in-Marsh, ca. 3/4 mile north of Stow-on-the-Wold (SP 193271); Workhouse Quarry, Chipping Norto9n, Oxfordshire (SP 319276); Great Oolite of Sarsgrove Sarden, Chipping Norton, Wiltshire, England.

    Lectotype: SDM 44.19, right ilium. Oakham Quarry (S. Reynolds 1939, fig. 8)

    Referred specimens: SDM 44.1, left maxilla. New Park Quarry (S. Reynolds 1939, fig. 10)
    BMNH R8303, left maxilla. New Park Quarry
    BMNH R8304, left dentary rostral fragment. New Park Quarry
    GSM 37523, dorsal. Moreton-in-Marsh
    SDM 44.6, caudal dorsal. New Park Quarry (S. Reynolds 1939:199, his # 2)
    SDM 44.10, dorsal. New Park Quarry (S. Reynolds 1939, fig. 6a)
    BMNH R9679, sacrum. New Park Quarry
    BMNH R9680, sacrum. New Park Quarry
    SDM 44.4, sacrum. New Park Quarry (S. Reynolds 1939, fig. 6a)
    BMNH R9672, proximal caudal. New Park Quarry
    BMNH R9673, proximal caudal. New Park Quarry
    BMNH R9677, proximal caudal. New Park Quarry
    OUM J13720, proximal caudal. ?Workhouse Quarry
    OUM J29799, proximal caudal. Workhouse Quarry
    BMNH R9675, midcaudal. New Park Quarry
    BMNH R9676, midcaudal. New Park Quarry
    SDM 44.5, midcaudal. New Park Quarry
    SDM 44.7, more distal caudal. New Park Quarry
    OUM J29800, right scapula. Workhouse Quarry
    SDM 44.16, fragmentary proximal right scapula. Oakham Quarry (S. Reynolds 1939:202, his "f")
    SDM 44.17, partial proxima right scapula. Longborough Road Quarry (S. Reynolds 1939:202, his "f")

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  2. Stephan PickeringApril 9, 2010 at 3:08 PM

    SDM 44.14, right coracoid. New Park Quarry (S. Reynolds 1939:193, fig. 7a)
    SDM 44.15, right coracoid. New Park Quarry (S. Reynolds 1939:201)
    SDM 44.18, left humerus. New Park Quarry (S. Reynolds 1929:202, his "g")
    SDM 44.22, left humerus. Longborough Road Quarry (S. Reynolds 1939:202, his "left ischium")
    BMNH R9668, right ischium. New Park Quarry
    SDM 44.20, imperfect left ischium. New Park Quarry (S. Reynolds 1939:202, ischium # 1, fig. 7b)
    SDM 44.21, distal left ischium. New Park Quarry (S. Reynolds 1939:202, ischium # 2)
    SDM 44.24, right femur. New Park Quarry (S. Reynolds 1939:204)
    BMNH R413, right metatarsal III. Sarsgrove (Lydekker 1888B:163)
    BMNH R9665, left metatarsal III. Oakham Quarry
    SDM 44.25, distal left metatarsal IV. New Park Quarry (S. Reynolds 1939:204, his "k")

    DIAGNOSIS: Megalosauridae with sacral 4 longer ventrally than dorsally. The hypodigm indicates a Metriacanthosaurus with an illium having a more horizontal crest; the anterior blade is lower; the posterior blade is also lower, but begins much higher above the base of the peduncle, with a much greater area exposed below the spine; the public peduncle is longer; the ischial peduncle is much longer, the notch more open.

    Most of your comments above, while interesting, are hampered by the fact that I have before me the original 1972 photographs + detailed illustrations of each specimen. The mss. devotes 2 1/2 pages of descriptive analyses to SDM 44.19, e.g.

    Compared with Metriacanthosaurus parkeri OUM J12144 (A. Walker 1964, fig. 16e), which is damaged, the length between notches is slightly greater; the crest is more nearly horizontal, especially caudally. The height at the pubic peduncle is much higher above the base of the peduncle. The spine is lower, but is much higher above the blade. The public peduncle is longer, the notch similar. The acetabulum is higher and longer, its medial arch much lower. The ischial peduncle is much longer, the notch higher and even more open. Although there are obvious differents between them, SDM 44.19 is more like OUM J12144 than other taxa.

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  3. Stephan PickeringApril 9, 2010 at 3:10 PM

    Compared with Eustreptospondylus OUM J13558, it is nearly twice as large, 300 vs. 165 mm between the notches. The height above the pubic peduncle is much greater than the internotch distance. The anterior blade is missing in both, as is the posterior blade in SDM 44.19. The cranial notch is more open. The base of the spine originates higher above the acetabulum, thus revealing more of the lower part of the posterior blade. The pubic peduncle is longer, its craniodistal end eroded. The acetabulum is higher, especially cranially, and its medial border is very much lower. The ischial peduncle is blunter.

    Compared with the largest ilium of M. bucklandii OUM J13560 (A. Walker 1964, fig. 16d), SDM 44.19 is even larger, 300 vs. 285 mm between the notches. The crest is straight. The anterior blade is 200 vs. 183 mm high. The posterior blade originates higher, and has a more steeply dipping ventral edge. The spine is about the same height, but originates much higher, its ventral edge dipping cranially vs. caudally. The pubic peduncle is much longer cranially, the notch wider. The acetabulum has a similar best crest, but is lower (216 vs. 270 mm), its medial border much lower. The ischial peduncle is longer and recurved distally, the notch is even more open.

    Needless to say, the hypodigm is Metriacanthosaurus. I can understand the frustration workers have, especially when they rely either upon Benson (who plunders Sam's original mss. without attribution) or Day & Barrett. Just because they state specimens are Megalosaurus does not mean they are Megalosaurus.

    A further observation, contra Benson (I have the French sources he refers to):
    Megalosauridae Huxley 1869
    = Megalosauria Baur 1891
    = partim, Megalosauroidea Nopcsa 1928
    = Megalosaurinae Nopcsa 1928
    = partim, Megalosauroidea Hay 1930 nomen nudum
    = Torvosauridae Jensen 1985
    = Intertheropoda G.S. Paul 1988 nomen nudum
    = Eustreptospondylidae G.S. Paul 1988 nomen nudum
    = Eustreptospondylinae G.S. Paul 1988 nomen nudum
    = Metriacanthosaurinae G.S. Paul 1988 nomen nudum
    = partim, Avetheropoda G.S. Paul 1988 nomen nudum
    = Torvosauroidea Sereno et al. 1994
    = partim, Neotetanurae Sereno et al. 1994

    Megalosaurus Buckland 1824
    = Megalosaurus Parkinson 1822 nomen nudum
    = Thegalosaurus [sic] E.D. Cope 1872
    = Megalousaurus [sic] Ameghino 1913
    = Megalasaurus [sic] von Huene 1926
    = Megalosausus [sic] von Huene 1926
    = Megolosaurus [sic] von Huene 1926
    = Meqalosaurus [sic] A. Walker 1964
    = Torvosaurus Galton & Jensen 1979
    = Torovosaurus [sic] Kurzanov 1989

    Again, Mickey, I am delighted with all of this: this is dinosaurology at its finest, when specimens and observations can be shared, debated, corrected, elaborated.

    Kol tuv uv'racha.
    STEPHAN / Chofetz Chayim ben-Avraham

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  4. Stephan PickeringApril 9, 2010 at 4:09 PM

    In going through my Mutanda Dinosaurologica files, I inadvertently forgot to add to Megalosauridae:
    = Megalosauri Fitzinger 1843 nomen oblitum

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  5. Stephan PickeringApril 9, 2010 at 5:03 PM

    I haven't sorted through all of the taxonomic revisions in the evolving Mutanda Dinosaurologica, but this is a tentative outline of what I have been using:

    Panaves Gauthier & de Queiroz 2001
    Dinosauria Owen 1842
    Theropoda Marsh 1881
    Tetanurae Gauthier 1984/1986
    Megalosauroidea Nopcsa 1928
    [this cannot be credited to Fitzinger 1843, because his nomen oblitum Megalosauri was a family]
    = Torvosauroidea Sereno et al. 1994 [Jensen never used the word]
    = Spinosauroidea Olshevsky 1995 [Stromer never used the word]

    If anyone has an alternative, I'd be interested in seeing it.

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  6. Thanks for the fine compendium of info, Stephan. I'll update my website entry accordingly for when I upload it. I don't suppose you could send me your equivalent list for Megalosaurus bucklandii? I have several specimens noted whose provenance and reference history I do not know.

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  7. Okay, after reading your comments I've revised a few element referrals. I agree you have the advantage of possessing the 1972 MS, and have changed my entry to reflect the anteroventrally eroded pubic peduncle. Yet I note we agree on how SDM 44.19 compares to M. parkeri and Eustreptospondylus. Ignoring size (as the Eustreptospondylus holotype is a subadult), the "height above the pubic peduncle is much greater than the internotch distance" and pubic peduncle longer in Megalosaurus too, so these don't indicate SDM 44.19 is Metriacanthosaurus. "The base of the spine originates higher above the acetabulum, thus revealing more of the lower part of the posterior blade" and "The acetabulum is higher, especially cranially, and its medial border is very much lower" are just as different between SDM 44.19 and parkeri. This leaves only the wider subpreacetabular notch (which isn't that much narrower in Eustreptospondylus) and blunt ischial peduncle as potentially uniting SDM 44.19 and parkeri. To me this does not substantially overcome the resemblence between the broadly exposed brevis fossae in SDM 44.19 and Eustreptospondylus. So my question is twofold- do you have any other Metriacanthosaurus synapomorphies in SDM 44.19, and have you compared it to "Szechuanosaurus" zigongensis, which seems more similar to it than parkeri (except the narrow subpreacetabular notch)?

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  8. SDM 44.19 (S. Reynolds 1939, fig. 8). The Reynolds figure is not especially useful, and I shall be using in Mutanda Dinosaurologica the magnificent illustration Sam provided me.

    This is a large ilium, 300 mm between the notches, 380 mm high above the pubic peduncle x 216 mm high above the notch. Both blades are broken, leaving only the central body. The crest is nearly straight. The pubic peduncle is stout, with a straight pubic facet. The ischial peduncle is short and rounded. The spine begins far from the acetabulum, and high above the posterior blade, so a wide band of the latter is exposed below the spine. The acetabular crest is highly (144 mm) arched. The cranial notch is wide open.

    Comparison with other taxa are above.

    Compared with Allosaurus fragilis USNM 4734 (Gilmore 1920B, pl. 10) the differences are much the same as from Megalosaurus bucklandii OUM J13560. The crest is straighter, the blade lower, especially cranially. The anterior blade slops up more steeply from a wider cranial notch. The pubic peduncle is shorter. The ischial peduncle is ventrally thicker, the notch higher. The posterior blade originates higher above the peduncle, while the higher base of the spine exposes much more of the posterior blade. The acetabular crest forms a high arch vs. slanting cranioventrally. The medial border of the acetabulum is much lower.

    Another point is that the partial left ischium SDM 44.20 has a caudally convex shaft, the distal end enlarged, but not expanded into the foot as in Metriacanthosaurus parkeri OUM J12144. SDM 44.21, a distal left ischium, 394 mm long, the distal end 111 x 64 mm, and although the caudodistal corner is broken away, very little is missing, probably less than 10 mm. The slight distal expansion, as in SDM 44.20, contrasts with OUM J12144, where the foot is ca. 180 mm long, and with Megalosaurus bucklandii OUM J13565 (Buckland 1824A, pl. 44 figs. 3-4) where the foot is 127 mm. However, on the basis of similarities to other elements of the hypodigm, Sam Welles believed Metriacanthosaurus reynoldsi is Metriacanthosaurus, vs. erecting a 'Megalosaurus' reynoldsi.

    STEPHAN PICKERING / Chofetz Chayim ben-Avraham
    The Dinosaur Fractals Project

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  9. Another taxon is Metriacanthosaurus huxleyi, a name reserved in Mutanda Dinosaurologica for a homologous diagnostic hypodigm should this be found.
    Jurassic, Bathonian, Sharp's Hill Formation, Workhouse Quarry, Chipping Norton, Oxfordshire.
    Proposed type: BMNH R283, right ilium.

    This is a Metriacanthosaurus with an ilium having pronounced buttresses, a high anterior blade with nearly horizontal ventral edge. The spine is very high caudally, the acetabular crest continues onto the ischial peduncle. The ischial peduncle is massive with a nearly vertical caudal edge.
    Compared with Metriacanthosaurus parkeri OUM J12144 (von Huene 1926B, fig. 49; A. Walker 1964, fig. 16e), which is poorly preserved, the two are different, 584 mm long vs. 712, height above the pubic peduncle 278 vs. 436 mm, H:L index 48 vs. 61. The buttresses on the blade are much stronger. The anterior blade is lower. The posterior blade has a more horizontal dorsal edge, its ventral edge much steeper. The spine has a horizontal ventral edge. The pubic peduncle is shorter, the notch narrower. The acetabular crest arches down onto the ischial peduncle, and the peduncle is ventrally thicker and has a vertical cranial edge, so that the notch is much wider. Although these differences are distinct, the shortness of BMNH R283 and the great height of its anterior blade clearly places BMNH R283 within Metriacanthosaurus and NOT Megalosaurus (contra Benson 2010B:885).
    Compared with Metriacanthosaurus brevis BMNH 31811 (R. Owen 1857A text), it is 584 x 278 vs. 640 x 393 mm, H:L index 48 vs. 61.
    Compared with Megalosaurus bucklandii BMNH R1100 (R. Owen 1857A, pl. 6), it is 585 vs. 757 mm long. The buttresses on the blade are much more pronounced. The anterior blade is much higher, its ventral edge aligned with that of the spine vs. dipping steeply cranially. The posterior blade has its ventral edge dipping steeply cranially. It originates a little higher on the peduncle, ending in a point beyond the spine. The spine is higher. The pubic peduncle is shorter, with a horizontal ventral edge. The acetabular crest is continuous down the ischial peduncle, lacking the notch above the peduncle. This peduncle is more massive, its caudal face vertical vs. recurved distally. The caudal notch is wider.
    STEPHAN PICKERING / Chofetz Chayim ben-Avraham
    The Dinosaur Fractals Project

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