LYDEKKER (1890) referred Omosaurus armatus to the. North American genus ... 5 pairs of sacral ribs) of Dacentrurus from England, France and Portugal and ...
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Geologica et Palaeontologica
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25 1s. 299-327
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9 Abb., 3 Tab., 3 Taf.
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Marburg, 30.9. 1991
Postcranial remains of stegosaurian dinosaur Dacentrurus from Upper Jurassic of France and Portugal Peter M . GALTON with 9 Text-figures, 3 Tables and 3 Plates GALTON, Peter M.: Postcranial remains of stegosaurian dlnosaur Dacentrurus from Upper Jurassic of France and Portugal. - Geologica et Palaeontologica 25:299-327,9 Text-figs., 3 Tabs., 3 Pls.; Marburg, 30.9.1991. Dacentrurus lennieri (NOPCSA, 1911) from the Lower Kimmeridgerian of Normandy, France is 1875) from England. Several parregarded as a junior synonym of Dacentrurus armatus (OWEN, tial skeletons from the Middle Icimmeridgian to the Upper Tithonian of Portugal are referred to
D. armatus. The neck consists of 12 vertebrae and the sacrum of 7 fused centra, that include 2 dorsosacrals, and either 4 or 5 pairs of sacral ribs. An egg from Portugal is the only one found associated with bones of a stegosaur. The presence of a shoulder spine should not be used as a character which links nodosaurids and stegosaurids but is absent in ankylosaurids.
Dacentrurus lennieri (NOPCSA, 1911) aus dem Kimmeridgium der Normandie in Frankreich 1875) angesehen. Mehrere in Teiwird als jiingeres Synonym von Dacentrurus armatus (OWEN, len erhaltene Skelette aus dem Mittleren Kimmeridgium bis zum Ober-Tithonium Portugals werden zu D. armatus gestellt. Der Hals besteht aus 12 Wirbeln und das Becken aus 7 verschmolzenen Zentren (2 Dorsosacralia und entweder 4 oder 5 Paar Sacral-Rippen). Ein Ei aus Portugal ist der einzige Fund in Zusammenhang mit den Stegosaurier-Knochen. Die Anwesenheit eines Schulter-Stachels kann nicht als verbindendes Merkmal zwischen Nodosauriern und Stegosauriern betrachtet werden, denn er fehlt den Ankylosauriern. Address of the author: Prof. Dr. Peter M. Galton, Department of Biology, University of Bridgeport, Bridgeport, Connecticut 06601-2449, U.S.A.
Contents Introduction . . . . . . . . . . . lMaterial and Description . . . . . . France . . . . . . . . . . . . Portugal . . . . . . . . . . . Ages of Specimens. . . . . . Description of Specimens . . . Comparisons . . . . . . . . . . . Status of Dacentrurus lennieri (NOPCSA, Systematics . . . . . . . . . . . Acknowledgements . . . . . . . . Literature . . . . . . . . . . . . Abbreviations used in illustrations . .
Introduction The first articulated material of a stegosaurian dinosaur to be described from anywhere in the world was Omosaurus armatus OWEN,1875, the holotype (BMNH 46013) of which is a reasonably complete skeleton lacking the skull that came from the Lower Kimmeridge Clay (Upper Jurassic) of Swindon, Wiltshire, England. The discovery occurred in the upper beds of the brick-pit of the Swindon Brick and Tile Co., at the foot of Old Swindon Hill (at west end of Swindon Hills) and adjoining the Wilts and Berks Canal (DAVIES,1876). The exact horizon is not known, and the productive pits were
abandoned long ago, but ARKELL(1933), who gave a summary of the succession at Swindon, noted that most of the vertebrate remains came from the lower beds, especially the Aulacostephanus pseudomutabilis Zone and the underlying Rasenia mutabilis Zone (now the Aulacostephanus eudo.~us and A. mutabilis zones of the Lower Kimmeridgian, see COPE et al., 1980). A pair of dermal tail spines (BMNH 46320), the holotype of Omosaurus hastiger OWEN,1877, came from the same division of the Kirnmeridge Clay as 0 . armatus in the Great Western Railway cutting at Wootton Bassett, Wiltshire, but no details of this sequence were ever published (ARKELL, 1933). LYDEKKER (1890) referred Omosaurus armatus to the North American genus Stegosaurus MARSH, 1877 as S. armatus (OWEN). SEELEY(1893) maintained the generic separation of Omosaurus. L u c ~ s(1902) made ~ m & s a u r u s armatus OWEN, 1875 the type species of the genus Dacentrurus because, as was first noted by O.C. MARSH(in LYDEKKER, 1888), Omosaurus was preoccupied (LEIDY,1865). The use of Omosaurus instead of Dacentrurus has continued until very recently and whichever name was used is followed in this survey. The holotype of Dacentrurus armatus (OWEN) and several referred specimens from England (including holotype of Omosaurus hastiger OWEN,1877) were described by GALTON(1985), along with the other English stegosaurs. These are represented by fragmentary material except for Lexovisaurus HOFFSTETTER, 1957 (with Omosaurus durobrivensis HULKE,1887 as the type species) from the Lower Oxford Clay (Middle Jurassic, lowermost Middle Callovian) of Fletton near Peterborough. The material of Lexovisaurus durobrivensis (HULKE,1887) from Fletton con-
300
GALTONPostcranial remains of stegosaurian dinosaur Dacentrurus from Upper Jurassic of France and Porrugal
sists of several specimens that include two partial skeletons, the holotype (BMNH R1989) and BMNH R3167, the holotype of Stegosaurus priscus NOPCSA,1911b. In addition, there is a partial skeleton from the uppermost Lower Callovian marls of Le Fresne d'drgences in Normandy, France (GALTON,1990a). All the genera of stegosaurs are reviewed by GALTON(1990b). Omosaurus lennieri NOPCSA,1911a was based on a partial skeleton from the Lower Kimmeridgian (Aulacostephanus mutabilis Zone, RIOULT,1978; Kimmeridgian sensu gallico is equivalent to only the Lower Kimmeridgian sensu anglico, HALLAM,1975) on the beach of Octeville (see NOPCSA,1911a: PI. l ) , about 30 m north of the Etapeniers Road, Cap de La Hkve, Normandy, France (Text-fig. 1A). This partial skeleton (Text-figs.2, 3, 4C-F, 9D) was excavated by SAVALLE & LENNIER(1899) but it was destroyed in 1944 when the Museum d'Histoire Naturelle in Le Havre was hit by an incendiary bomb. There are no casts of this specimen but the recently discovered distal end of a femur was referred to Dacentrurus lennieri by GALTON& BOINE(1980).This partial femur came from the mutabilis Zone of the cliffs of La Brikre at Octeville (GALTON & BOINE,1980).A section of these cliffs is given by GUYANDER (1968: Fig. 16) and this locality is only about 1km northeast from the type locality (Text-fig.1A). ZBYSZEWSKI (1946) and LAPPARENT & ZBYSZEWSKI (1957, abstract 1951) described several incomplete skeletons, that they referred to Omosaurus armatus and 0 . lennieri, from the Upper Jurassic (as .Upper Lusitanian. and *Kimmeridgianocteville ~ i l ~ ~ 1911a1. (mutabilis Zone, Lower Kimmeridgian sensu anglico) at the base of the cliffs at Octeville, de ~ k ~~~~~~d~ ~ ~ , C H -height of centrum; CL- maximum length of centrum; C W ~ - maximum width of centrum anreriorl~;CWP - maximum width (Text-fig. 1A). The associated fauna and the paleogeography of centrum posteriorly; N C - maximum width of neural canal; of the region during the jurassic are summarized by VH - maximum heigth of vertebra.
cap
upper
RIOULT(1978).
Text-figs. 2,3,4C-F, 9D; Tabs. 1 , 2
This specimen was well described by NOPCSA(1911a) but it was destroyed in 1944 and there are no casts. The holotype of
Omosaurus lennieri NOPCSA,1911a consisted of a partial skeleton that was excavated by SAVALLE& LENNIER(1899) about 30 m north of the ~tapeniersRoad (Text-fig. 1A; see NOPCSA,1911a: P1.l for drawing of site).
Text-fig.2: Upper Jurassic stegosaurid Dacentrurus lennieri (Norcsil, 1911 a), h o l o t ~ p eM H N H A from Octeville Marls of Octeville, France [from NOPCSA, 1911a]. C e r v i c a l v e r t e b r a e . - Third: 1)right lateral view, X 0.36; 2) anterior view, X 0.33. - Seventh: 3) left lateral view, x 0.33; 4) anterior view, X 0.33; 5) ventral view, X 0.33. - Tenth: 6) right lateral view, X 0.36; 7) anterior view, X 0.33; 8) ventral view, x 0.33. -Eleventh: 9) left lateral view, x 0.4; 10)posterior view, X 0.25. -For abbreviations see: 320.
302
GALTON Postcranial remains of stegosaurian dinosaur Dacentrurus from Upper Jurassic of France and Portugal
Cervical vertebrae NOPCSA(1911a) identified the seven preserved neck vertebrae as cervicals 3-5,7 and 10-12 and this seems reasonable (Textfig. 2, Tab. 1).Passing along the series (Text-fig.2), the centra increased in height and increased and then decreased slightly in length and width, the level of the middle part went from above to below the ventral edge of the ends (Text-figs.2.1, 2.3, 2.6, 2.9), the outline of which changed from subrhomboidal to oval to roughly heart-shaped (Text-figs.2.2, 2.4, 2.7,2.10). The maximum length of the centrum exceeded its maximum width in cervicals 3 to 7 whereas in cervicals 10 to 12 the reverse was the case. The parapophyses became more dorsally situated and the diapophyses became more elongate. The neural arches and spines became taller and the neural canal reached its maximum size in cervical 10. The cervical rib was fused to the parapophysis and diapophysis in cervicals 3-5.7 and 10 (but not in 11 and 12) to form a transverse foramen as in mammals (Text-figs. 2.2,2.4). Dbrsal vertebrae Seven dorsals were originally present but only two were described and illustrated (Tab.l):dorsal 2 (Text-figs. 3.1, 3.2) and the best preserved of six anterior dorsals (Textfigs. 3.3-3.5). The maximum width of the centra exceeded the maximum length, the solid pedicel-like part of the neural arch was low, and the transverse processes were at an angle of about 35" to the horizontal (Text-fig.3.3).
The sacrum consisted of seven fused centra. the first of which was incomplete anteriorly, and five pairs of sacral ribs, those of the right side being represented by the proximal ends whereas the left ribs were complete with the ilium attached (Text-figs.4D, 9D, Tabs.1, 2). The sacra of Kentrosaurus (Upper Jurassic, Tanzania) consist of six fused centra and either four or five pairs of sacral ribs, with the additional pair of ribs being slender and borne by the first sacral vertebra (GALTON,1982 a). This sacrum (Text-figs. 4D, 9D) was of the five ribbed type and comparisons with the sacra of Kentrosaurus show that ventrally sacral ribs 4, 3 and 2 were borne mostly by the centra of sacral vertebrae 5, 4 and 3, respectively. The first sacral rib was carried by centra 2 and 1, and the additional sacral rib was carried by the first sacral centrum. Consequently, there were two dorsosacral vertebrae (Text-figs.4D, 9D) rather than one as in Kentrosaurus. The posterior dorsosacral vertebra helped to support the dorsal LF BMNH MSGPA IST A MSGP B BOIhE MHNH A MSGP C MSGP D MSGP F MSGP H
1242 1085 953 925
t790 730
-
537
WFp
360 300 265 236
Gt
NF
-
155 125 95
HF
-
75
The left ilium was complete except for the end of the anterior process and the maximum preserved length was 550 mm (Text-figs.4D, 9D). The bone extended to within 100 and 120 mm of the neural spines so its gently convex surface formed most of the back in this region (Text-fig.4C). However, the ilium was very shallow, being only 175 mm deep at the prominent pubic peduncle and 125 mm deep at the shorter ischiadic peduncle (Text-fig. 4D). The acetabulum was roughly rectangular in outline, was more strongly concave anteroposteriorly than transversely (Text-fig.4D), and faced more ventrally than laterally (Text-fig.4C). The acetabulum was clearly delimited medially but laterally it was separated only by a low ridge from the concave surface of the antitrochanter or supra-acetabular flange, the rugose edge of which extended 95 mm beyond the acetabulum (Text-figs.4C, D). Pubis a n d ischium Only the posterior ends of both bones were preserved (Textfigs.3.6, 3.7). The posterior part of the pubis was rod-like with an expansion distally where it was fused to the ischium (Text-fig.3.6). Transversely, the distal part of the ischium was convex medially, concave laterally, and triangular in section MC
IC
LC
Wdp
L1
-
215
-
153
225
800
130
-
128 100
180 120
-
214
100
155 127
225 210
700
-
-
-
223 139 127
I05 56
88
-
-
77
-
The incomplete first caudal vertebra was exposed in anterior view on top of the sacral plate (Text-fig.4E, Tab. l). The transverse process was thin but deep with a prominent dorsal process. Ilium
240 170 202 175
l55 145 112
220
-
Caudal vertebra
330 300 233 242 240
-
115
WFd
Dart of the additional sacral rib that was inclined obliquely anterodorsally from the centrum of the first sacral vertebra (Text-fig.4D). The transversely expanded and convex tops of the neural spines of sacral vertebra 1 to 4 were fused together to form a single cylindrical enlargement (Text-fig.4E, posterodorsal part of 4 missing). Ventral to this, a gap separated the spines of sacral vertebrae 1 and 2 but the junction between spines 2-3 and 3-4 was indicated only by a shallow groove on the neural plate. The dorsal sacral plate formed by the transverse processes and the tops of the sacral ribs was perforated by four elongate foramina on each side of the neural plate (Text-fig.4E). Ventrolaterally, there was a small foramen between the additional sacral rib and the adjacent part of the ilium (Text-figs. 4D, 9D). The first sacral rib was the most robust and the next three were progressively less massive. The expanded distal end of the last rib was incompletely preserved.
-
-
-
-
1058
Wla
WII
668 590
a
-
-
570
465
b c
-
d
500
458
752
-
-
140
-
Tab. 2: Dacentrurus from England, France and Portugal, measurements (in mm) of femora (arranged in order of descending size) and ilia a - BMNH 46013; b-d - midshaft widths anteroposterior X transverse: b - 95 X 125; c - 66 X 120; d - 65 X 97; Gt - anteroposterior w ~ d t h of greater trochantel; HF - anteroposterior wldth of head, IC - anteroposterlor w ~ d t hacross lntercondylar region; LC - anteroposterlor wldth across lateral condyles; LF - maximum length of femur; L1 - maximum length of ilium; M C - anteroposterior width across medial cond~les;NF - minimum anteroposterior width across proximal end of femur; Wdp - perpendicular (to LC and MC) distal width of femur; WFd - maximum width of distal end of femur; WFp - maximum proximal width of femur; WIa - maximum perpendicular transverse width from midline to anterior end of ilium; WIf - maximum perpendicular transverse width from midline to antitrochanter (supra-acetabular flange) of ilium.
Text-fig. 3: Upper Jurassic stegosaurid Dacentrurus lennieri (NOPCSA, 1911a), h o l o t y p e MHNH A from Octeville Marls of Octeville, France [from NOPCSA, 1911a]. D o r s a l v e r t e b r a e . - Second: 1)right lateral view, X 0.28; 2) posterior view, X 0.25. - Anterior dorsal: 3) anterior view, X 0.25; 4) left lateral view, X 0.32; 5) ventral view, X 0.5. - Distal ends of p u b e s and i s c h i a : 6) right in approximately lateral view; 7) both in dorsal view. -For abbreviations see: 320.
with a thin edge that was attached to the pubis distally or separated from it by about 5 mm more proximally. The enlarged end of the ischium was much roughened medially, indicating that the ischia were strongly bound together by ligaments. Both ischia were strongly curved towards the midline (Text-fig.4F), rather than being only gently curved as in other specimens of Dacentrurus (PI.2, Fig. 11; GALTON,1985). U
,
Femur The proximal 570 mm of the femur was preserved (Tab.2) but only the proximal end was illustrated as a longitudinal section in articulation with the ilium (Text-fig.4C). The lesser trochanter was set a bit below the head, from which it was not clearly separated, and there was no trace of the lesser trochanter. The broken end was nearly rectangular in section, measuring 105 mm transversely by 72 mm, and the indistinct outline of the medullary cavity measured 45 by 33 mm. The remnant of the fourth trochanter was represented by a rugose ridge on the posterior surface. 2. BOINEA Tab. 2
Distal half of a left femur (see GALTON& BOINE,1980: P1.1, Figs. 1-7) that was found at the base of the cliff at La BriAre (for cliff section see GUYANDER, 1968: Fig.16) about l km northeast of the type locality.
PORTUGAL Ages of Specimens Most of the specimens came from the Upper Jurassic of central Portugal to the north of Lisbon (Text-fig. l B ) . An overall summary of the stratigraphy and paleogeography of this region is given by LEINFELDER (1987). The stratigraphy and invertebrate faunas of the beds in the region, plus geological sections at most of the sites that produced Dacentrurus, are given by LAPPARENT & ZBYSZEWSKI (1957: 13-18). The ages for the specimens was given by LAPPARENT& ZBYSZEWSKI (1957) as either Upper Lusitanian (sites at Alfeizerao, MSGP C; San Bernardino, IST A) or Kimmeridgian. R. R. L e i n f e l d e r (personal communication) notes that the marine former .Upper Lusitanian. is currently regarded as representing the entire Kimmeridgian with the Abadia beds as upper Upper Oxfordian to lower Upper Kimmeridgian and the Amaral beds as upper Upper Kimmeridgian. The marine former .Kimmeridgian
