[D] Megalosaurus crenatissimus
Describer
Deperet, 1896
Time
Cretaceous Late Campanian
Classification
Saurischia Theropoda Abelisauridae
Diet
Carnivore
Fossilsite
Madagascar
Fall Under
Majungasaurus
Info
Majungasaurus (Lavocat, 1955) > Majungasaurus crenatissimus (Deperet, 1896) >> Megalosaurus crenatissimus (Deperet, 1896)
Majungasaurus > Majungatholus atopus (Sues & Taquet, 1979)
Extract from the bulletin de la société géplogique de France 3rd series, volume XXIV, page 176, 1896. Note on the suaropod and theropod dinosaurs from the Upper Cretaceous of Ma dagascar by Charles DEPÉRET.
Translated by Matthew Carrano Department of Anatomical Sciences SUNY at Stony Brook, September 1999
Megalosaurus crenatissimus, n. sp.
Descriptions
I attribute the following elements to a megalosaurid of moderate size:
1st. Two teeth, of which one is nearly complete up to the base of the crown, and the other is larger but incomplete below. These teeth show the typical characters of megalosaurid teeth: a transversely compressed shape with two sharp ridges anteriorly and posteriorly, the latter more trenchant than the anterior: a recurved posterior profile in the shape of a saber blade; fine transverse serrations on the trenchant ridges: these serrations extend along the entire length of the anterior edge. The enamel is finely striated lengthwise.
2nd. An ungual phalanx in the shape of a recurved claw, unfortunately broken near the point. A blunt ridge that runs over the convex or superior edge along its entire length separates two oblique lateral faces, of which one – doubtless located on the external side – is more developed than the other: this asymmetry of the phalanx makes it possible to think that it is the claw of a lateral digit. Each of the two faces is covered near the base by a wide, curved vascular groove that leaves the inferior edge and moves while rising towards the terminal point of the claw. The posterior or articular face shows indications of two shallow articular excavations, the external being wider, separated by a slightly vertical ridge.
3rd. Two sacral vertebrae are compressed in the middle of the centrum, according to the ordinary type of megalosaurids.
4th. A very elongated caudal vertebra, clearly amphicoelous, whose centrum shows a quadrangular cross-section, higher than wide. A slight median longitudinal crest is visible below, bordered by two weakly marked grooves. The neural arch is inserted along nearly the entire length of the centrum, only a centimeter of which is free posteriorly. A median longitudinal ridge represents the only indication of a spinous process. No surface for the chevrons is seen, which permits attributing this element to the post-median region of the tail. There is an extremely straight neural canal, of elliptical shape. The anterior and posterior zygapophyses are broken.
Relationships and differences
The characters drawn together from the teeth, the ungual phalanx, and the amphicoelous caudal vertebra described above do not allow any doubt regarding the existence of a predatory dinosaur in Madagascar close to Megalosaurus Buckland from the Jurassic and Cretaceous of Europe, and of a genus near Dryptosaurus Marsh (Laelaps Cope) from the Cretaceous of the United States.
If the elements from Madagascar are compared with those of the type species, Megalosaurus bucklandii Meyer from the Lower Jurassic of England and France, important differences are recognized: the mandibular teeth (1) are higher, but straighter, with much coarser serrations on the posterior edge, and above all on the anterior edge where they exist only on the superior part of the crown; this character is important to note, because the teeth from Madagascar, that of Fig. 4 in particular whose crown is less nearly complete, show serrations along the entire visible part of the anterior edge. The upper teeth of Megalosaurus bucklandii are similar to the lowers; the serrations only appear less marked.
The sacral vertebrae of this species clearly have the short, compressed shape Owen. Wealden a. Purbeck Reptilia, part III, pl. XII (Palaeont. Soc., 1856). Huxley. Quart. Journ. geol. Soc., vol. XXV, 1869, pl. XII. (3) Owen. Loc. cit., pl. II and III.in the middle of the centrum shown by the Malagasy vertebrae; these are only much smaller.
The caudal vertebrae from Madagascar entirely resemble the caudal vertebrae of Megalosaurus bucklandii (4) in their general shape and details; it is only still of more elongate proportions and smaller dimensions by about a quarter. Finally, the ungual phalanx is less transversely compressed and more flattened dorsoventrally than in Megalosaurus bucklandii (5); it differs further because the lateral groove ends behind the inferior edge of the bone much earlier than in the European species, where this short groove parallels the inferior edge nearly up to the proximal end of the phalanx.
Megalosaurus insignis (Eudes-Deslongchamps & Lennier,1870) from the Upper Jurassic of England and France is a very large species whose teeth have the same straight, elongated form as those of Megalosaurus bucklandii; they are less strongly recurved posteriorly than in the Malagasy species, the serrations of the trenchant anterior edge are weaker and cease on the inferior third of the length of the crown.
In Megalosaurus dunkeri Koken from the Wealden of England and Germany, the form of the teeth is likewise straighter and more elongated than in the Malagasy species; but the serrations are already finer and more closely resemble those of this latter type; however they disappear near the middle of the anterior ridge, as in the other European species, and are attenuated fairly easily by use along the entire length of this edge. The ungual phalanges of Megalosaurus dunkeri (3) are more slender and more transversely compressed than those of the Malagasy species, and the lateral groove remains parallel to the inferior edge instead of recurving below near the posterior third.
Mr. Seeley has described two teeth from the Upper Cretaceous beds of Neue Welt, near Vienna, under the name Megalosaurus pannoniensis that are much closer to the Malagasy teeth in the shape of the crown, which is shorter and wider at the base, and more finely serrated anteroposteriorly than in the other European species. However the posterior curvature is weaker than in the Malagasy species and the serrations cease on the inferior third of the anterior ridge instead of continuing along the entire length of this edge. I do not think that they could be attributed to the same species.
Above all, it is the species from the Arrialoor Group of Trichinopoly (British India), figured by Mr. Lydekker without specific designation, that the Malagasy teeth resemble entirely in shape, which is short, wide at the base, and strongly posteriorly recurved, and in the fineness of the serrations, which are likewise extended along the entire length of the anterior edge. Except for the much greater dimensions of the Indian type, no appreciable difference can be found with the Malagasy form, and this difference of size can be due either to the age of the subject or to the positional order of the tooth in the jaws. Therefore I think that I can join these two types together, and I will give the name Megalosaurus crenatissimus n. sp. to the species because of the serrations which are extended along the entire length of the two trenchant ridges of the teeth.
Some genera from the Jurassic and Cretaceous of America show great affinities with Megalosaurus. The best known is Dryptosaurus Marsh (Laelaps Cope) from the Upper Cretaceous of New Jersey. The type species Dryptosaurus aquilunguis Cope is very large, attaining the size of Megalosaurus bucklandii; the teeth differ entirely from those of Megalosaurus in the serrations of the anterior edge, which are extended along the entire length of this edge to near the root, instead of being limited to the upper part of the crown.
It is interesting to note that this character is found exactly in the Malagasy and Indian form, therefore the attribution to the genus Dryptosaurus is shown as entirely probable. It is true to add that Leidy expressed the opinion that the American genus was close enough to Megalosaurus of Europe not to be distinguished from it, and this opinion is all the more probable because that the known parts of the skeleton of Dryptosaurus are extremely similar to those of Megalosaurus . Therefore I will attribute the Malagasy species to the large genus Megalosaurus , while emphasizing its affinities with the species from the Upper Cretaceous of America distinguished under the name Dryptosaurus.
Megalosaurus crenatissimus, n. sp. — A predatory dinosaur is represented by two small, compressed teeth, anteroposteriorly recurved in the shape of a saber blade, of the typical form of Megalosaurus but shorter and wider than in all the European species of this genus and characterized above all by fine serrations that ornament the two trenchant ridges anterior and posterior to the crown, extended along the entire length of the anterior edge instead of only occupying part or two thirds of this trenchant edge. The name Megalosaurus crenatissimus , n. sp., is intended to emphasize this character, which is found in a Megalosaurus sp. noted by Mr. Lydekker in the Upper Cretaceous of India, and also in Dryptosaurus Marsh (Laelaps Cope) from the Upper Cretaceous of the United States.
I am thus brought to refer the type from Madagascar to the genus Dryptosaurus, which it is doubtless better to consider as a simple section of the large genus Megalosaurus. The other elements of Megalosaurus crenatissimus are: a sacral vertebra, a caudal of more elongate form than Megalosaurus bucklandii, and finally an ungual phalanx in the shape of a recurved claw, less transversely compressed than in other Megalosaurus, and furnished with a lateral groove that is less prolonged posteriorly than in the described species.
Source: Polyglot Paleontologist
Deperet, 1896
Time
Cretaceous Late Campanian
Classification
Saurischia Theropoda Abelisauridae
Diet
Carnivore
Fossilsite
Madagascar
Fall Under
Majungasaurus
Info
Majungasaurus (Lavocat, 1955) > Majungasaurus crenatissimus (Deperet, 1896) >> Megalosaurus crenatissimus (Deperet, 1896)
Majungasaurus > Majungatholus atopus (Sues & Taquet, 1979)
Extract from the bulletin de la société géplogique de France 3rd series, volume XXIV, page 176, 1896. Note on the suaropod and theropod dinosaurs from the Upper Cretaceous of Ma dagascar by Charles DEPÉRET.
Translated by Matthew Carrano Department of Anatomical Sciences SUNY at Stony Brook, September 1999
Megalosaurus crenatissimus, n. sp.
Descriptions
I attribute the following elements to a megalosaurid of moderate size:
1st. Two teeth, of which one is nearly complete up to the base of the crown, and the other is larger but incomplete below. These teeth show the typical characters of megalosaurid teeth: a transversely compressed shape with two sharp ridges anteriorly and posteriorly, the latter more trenchant than the anterior: a recurved posterior profile in the shape of a saber blade; fine transverse serrations on the trenchant ridges: these serrations extend along the entire length of the anterior edge. The enamel is finely striated lengthwise.
2nd. An ungual phalanx in the shape of a recurved claw, unfortunately broken near the point. A blunt ridge that runs over the convex or superior edge along its entire length separates two oblique lateral faces, of which one – doubtless located on the external side – is more developed than the other: this asymmetry of the phalanx makes it possible to think that it is the claw of a lateral digit. Each of the two faces is covered near the base by a wide, curved vascular groove that leaves the inferior edge and moves while rising towards the terminal point of the claw. The posterior or articular face shows indications of two shallow articular excavations, the external being wider, separated by a slightly vertical ridge.
3rd. Two sacral vertebrae are compressed in the middle of the centrum, according to the ordinary type of megalosaurids.
4th. A very elongated caudal vertebra, clearly amphicoelous, whose centrum shows a quadrangular cross-section, higher than wide. A slight median longitudinal crest is visible below, bordered by two weakly marked grooves. The neural arch is inserted along nearly the entire length of the centrum, only a centimeter of which is free posteriorly. A median longitudinal ridge represents the only indication of a spinous process. No surface for the chevrons is seen, which permits attributing this element to the post-median region of the tail. There is an extremely straight neural canal, of elliptical shape. The anterior and posterior zygapophyses are broken.
Relationships and differences
The characters drawn together from the teeth, the ungual phalanx, and the amphicoelous caudal vertebra described above do not allow any doubt regarding the existence of a predatory dinosaur in Madagascar close to Megalosaurus Buckland from the Jurassic and Cretaceous of Europe, and of a genus near Dryptosaurus Marsh (Laelaps Cope) from the Cretaceous of the United States.
If the elements from Madagascar are compared with those of the type species, Megalosaurus bucklandii Meyer from the Lower Jurassic of England and France, important differences are recognized: the mandibular teeth (1) are higher, but straighter, with much coarser serrations on the posterior edge, and above all on the anterior edge where they exist only on the superior part of the crown; this character is important to note, because the teeth from Madagascar, that of Fig. 4 in particular whose crown is less nearly complete, show serrations along the entire visible part of the anterior edge. The upper teeth of Megalosaurus bucklandii are similar to the lowers; the serrations only appear less marked.
The sacral vertebrae of this species clearly have the short, compressed shape Owen. Wealden a. Purbeck Reptilia, part III, pl. XII (Palaeont. Soc., 1856). Huxley. Quart. Journ. geol. Soc., vol. XXV, 1869, pl. XII. (3) Owen. Loc. cit., pl. II and III.in the middle of the centrum shown by the Malagasy vertebrae; these are only much smaller.
The caudal vertebrae from Madagascar entirely resemble the caudal vertebrae of Megalosaurus bucklandii (4) in their general shape and details; it is only still of more elongate proportions and smaller dimensions by about a quarter. Finally, the ungual phalanx is less transversely compressed and more flattened dorsoventrally than in Megalosaurus bucklandii (5); it differs further because the lateral groove ends behind the inferior edge of the bone much earlier than in the European species, where this short groove parallels the inferior edge nearly up to the proximal end of the phalanx.
Megalosaurus insignis (Eudes-Deslongchamps & Lennier,1870) from the Upper Jurassic of England and France is a very large species whose teeth have the same straight, elongated form as those of Megalosaurus bucklandii; they are less strongly recurved posteriorly than in the Malagasy species, the serrations of the trenchant anterior edge are weaker and cease on the inferior third of the length of the crown.
In Megalosaurus dunkeri Koken from the Wealden of England and Germany, the form of the teeth is likewise straighter and more elongated than in the Malagasy species; but the serrations are already finer and more closely resemble those of this latter type; however they disappear near the middle of the anterior ridge, as in the other European species, and are attenuated fairly easily by use along the entire length of this edge. The ungual phalanges of Megalosaurus dunkeri (3) are more slender and more transversely compressed than those of the Malagasy species, and the lateral groove remains parallel to the inferior edge instead of recurving below near the posterior third.
Mr. Seeley has described two teeth from the Upper Cretaceous beds of Neue Welt, near Vienna, under the name Megalosaurus pannoniensis that are much closer to the Malagasy teeth in the shape of the crown, which is shorter and wider at the base, and more finely serrated anteroposteriorly than in the other European species. However the posterior curvature is weaker than in the Malagasy species and the serrations cease on the inferior third of the anterior ridge instead of continuing along the entire length of this edge. I do not think that they could be attributed to the same species.
Above all, it is the species from the Arrialoor Group of Trichinopoly (British India), figured by Mr. Lydekker without specific designation, that the Malagasy teeth resemble entirely in shape, which is short, wide at the base, and strongly posteriorly recurved, and in the fineness of the serrations, which are likewise extended along the entire length of the anterior edge. Except for the much greater dimensions of the Indian type, no appreciable difference can be found with the Malagasy form, and this difference of size can be due either to the age of the subject or to the positional order of the tooth in the jaws. Therefore I think that I can join these two types together, and I will give the name Megalosaurus crenatissimus n. sp. to the species because of the serrations which are extended along the entire length of the two trenchant ridges of the teeth.
Some genera from the Jurassic and Cretaceous of America show great affinities with Megalosaurus. The best known is Dryptosaurus Marsh (Laelaps Cope) from the Upper Cretaceous of New Jersey. The type species Dryptosaurus aquilunguis Cope is very large, attaining the size of Megalosaurus bucklandii; the teeth differ entirely from those of Megalosaurus in the serrations of the anterior edge, which are extended along the entire length of this edge to near the root, instead of being limited to the upper part of the crown.
It is interesting to note that this character is found exactly in the Malagasy and Indian form, therefore the attribution to the genus Dryptosaurus is shown as entirely probable. It is true to add that Leidy expressed the opinion that the American genus was close enough to Megalosaurus of Europe not to be distinguished from it, and this opinion is all the more probable because that the known parts of the skeleton of Dryptosaurus are extremely similar to those of Megalosaurus . Therefore I will attribute the Malagasy species to the large genus Megalosaurus , while emphasizing its affinities with the species from the Upper Cretaceous of America distinguished under the name Dryptosaurus.
Megalosaurus crenatissimus, n. sp. — A predatory dinosaur is represented by two small, compressed teeth, anteroposteriorly recurved in the shape of a saber blade, of the typical form of Megalosaurus but shorter and wider than in all the European species of this genus and characterized above all by fine serrations that ornament the two trenchant ridges anterior and posterior to the crown, extended along the entire length of the anterior edge instead of only occupying part or two thirds of this trenchant edge. The name Megalosaurus crenatissimus , n. sp., is intended to emphasize this character, which is found in a Megalosaurus sp. noted by Mr. Lydekker in the Upper Cretaceous of India, and also in Dryptosaurus Marsh (Laelaps Cope) from the Upper Cretaceous of the United States.
I am thus brought to refer the type from Madagascar to the genus Dryptosaurus, which it is doubtless better to consider as a simple section of the large genus Megalosaurus. The other elements of Megalosaurus crenatissimus are: a sacral vertebra, a caudal of more elongate form than Megalosaurus bucklandii, and finally an ungual phalanx in the shape of a recurved claw, less transversely compressed than in other Megalosaurus, and furnished with a lateral groove that is less prolonged posteriorly than in the described species.
Source: Polyglot Paleontologist