[D] Megalosaurus chubutensis
Describer
Corro, 1974
Time
Cretaceous Late
Classification
Saurischia Theropoda Incertae Sedis \\\"Carnosaurs\\\" Nomina Dubia
Diet
Carnivore
Fossilsite
Cerro Castillo Formation, Provincia de Chubut, Argentina
Info
Tooth.
Corro del, (1999) \\\"Un nuevo megalosaurio (carnosaurio) del Cretacico de Chubut (Argentina)\\\". Paleontology Volume I, no. 5 Communicationes del Museo Argentino de Ciencias Naturales \\\"Bernardino Rivadavia e Instituto Nacional de Investigacion de las Ciencas Naturales. Director Jose Maria Gallardo [ A new megolosaur (Carnosaur) from the Cretaceous of Chubit (Argentina)
Translated by Matthew Carrano Department of Anatomical Sciences SUNY at Stony Brook April 1999
Introduction
This is the study of a tooth from a carnosaur of great size that was discovered by Drs. Ferello and Flores, geologists from the Yacimientos Petrolíferos Fiscales, in the course of the 1949 campaign in the province of Chubut. The tooth, which was given to the Museum, was found together with large bones that for obvious reasons were not extracted.
Order Saurischia
Suborder Theropoda
Infraorder Carnosauria
Family Megalosauridae Huxley 1870
Genus Megalosaurus Buckland 18241
1 F. von Huene (1956) said Megalosaurus Cuvier; Romer (1956) Megalosaurus Buckland 1822; Walker (1964), Megalosaurus Parkinson 1822, Lapparent and Lavocat in Piveteau, Traité de Paléontologie, V. 1955, gave Megalosaurus Buckland, 1824. von Huene in his Megalosaurus chubutensis nov. sp. Type. No. 18.189 Mus. Arg. C. Nat. \\\"B. Rivadavia\\\". Cat. Pal. Vert.
Description
Incomplete caniniform tooth, worn at the point, of large size, robust, and curved. The tooth in itself is not very well preserved. Its edges are sharp with very fine denticles, which generally are attentuated towards the apex in megalosaurids. The anterior part (convex) bears denticles that stop approximately 1 cm from the base, in contrast to the posterior part (concave) which bears denticles along the entire length of its edge.
The posterior face of the tooth is fairly convex, in contrast the anterior is nearly flat towards the posterior border. The surface of this caniniform2 tooth is polished, in parts showing enamel that is very finely striated in the vertical direction. The slightly concave undulations towards the point as seen in Megalosaurus saharicus Deperet& Savornin, 1927 and in Megalosaurus inexpectatus del Corro are not distinguished. Its aspect recalls the tooth of Megalosaurus insignis Eudes-Deslongchamps & Lennier, 1870, figured by de Lapparent (1943, pl. 1, fig. 1). On the base the tooth has an oval shape.
Measurements
Preserved length, taken on the anterior side, 74mm. Total length calculated circa 85 mm Maximum thickness at the base 22 \\\" Maxmimum width 35 \\\"
Horizon and Age
Cerro Castillo Formation. Upper Member. Middle Chubutian (= Green Tufas of Feruglio). Possibly the upper part of the Lower Cretaceous, \\\"The carnivorous Saurischia in the Jura and Cretaceous formations, principally in Europe,\\\" Rev. Mus. La Plata v. 29, 1926 (p. 45) expressed that the first description was made in 1824 by W. Buckland in Trans. Geol. Soc. London, no. 21, with the title, \\\"Notice on the Megalosaurus or great fossil lizard of Stonesfield,\\\" and that the species Megalosaurus bucklandii was thus named by H. von Meyer in 1832.
2 De Lapparent (1943) (p. 11) said that it was named thus among the megalosaurids one or various teeth enough larger than the others, situated towards the middle of the tooth row, and that had the functional role of canines in eminently carnivorous animals.
3 Feruglio in \\\"Descripción Geológica de la Patagonia\\\" 1949, vol. 1 (p. 245), mentioning the diverse fossil reptiles of the Chubutensian or Chubutian, wrote: \\\"That end to mention are so only the more important discoveries, because fragments and chips of bone are found in most other points, on all within the Upper Section of the Chubutensian, although not lacking either below, for at least towards the section inclusive of the Green Tufas\\\".
4 According to oral communication of Dr. M. A. Flores of Y. P. F. Geographic locality. North of Cerro Crettón. Mallín Grade farm. Department of Sarmiento. Province of Chubut (Argentina).
Comparisons
The caniniform tooth of Megalosaurus chubutensis nov. sp., different in size, by its form typical of megalosaurids, resembles Megalosaurus insignis Eudes-Deslongchamps & Lennier, Megalosaurus pannoiensis Seeley and Megalosaurus inexpectatus del Corro by the denticles of the anterior border, which end on its lower third; it differs from Megalosaurus superbus (1) Sauvage, Megalosaurus crenatissimus Deperet and Megalosaurus saharicus Deperet & Savornin by having denticles along the lengths of both sharp edges, from [Dryptosaurus medius] (Marsh) because these teeth also bear crenulations on both edges. Likewise Megalosaurus saharicus shows a series of concentric undulations on the tooth faces that are similar to those presented by Megalosaurus inexpectatus and that are not seen in the aforementioned species.
Considerations
Deperet & Savornin (1927:263) expressed that considering only the tooth characters, a series of \\\"continuous mutations\\\" could be conceived according to the disposition of the denticles on the sharp edges of the teeth. Meanwhile in all the species these denticles extend along the entire extent of the posterior edge, whereas they are limited to the upper third of the anterior edge in older species such as Megalosaurus bucklandii (Middle Jurassic), and are extended onto the upper half of this edge in more recent forms such as Streptospondylus cuvieri from the Oxfordian, Megalosaurus insignis (Kimmeridgian and Portlandian),
Megalosaurus dunkeri (Upper Jurassic, Purbeckian and Lower Cretaceous, Wealdian); in the Upper Cretaceous species such as Megalosaurus superbus (1) of the Albian and Megalosaurus crenatissimus of the Turonian (lower part of the Upper Cretaceous), the denticles are finer and extend along the entire anterior edge. Without doubt this is neither the case with Megalosaurus chubutensis (probably upper part of the Lower Cretaceous–Cenomanian or Turonian) nor Megalosaurus inexpectatus (Senonian–Upper Cretaceous), wherein as already noted the crenulations do not extend along the entire anterior face.
Likewise, in Megalosaurus insignis (Upper Jurassic) the crenulations of the anterior side begin or leave off slowly, in M. chubutensis the denticles are robust and begin or leave off almost brusquely, whereas in Megalosaurus inexpectatus the crenulations begin or leave off as in Megalosaurus insignis and are finer. This weakens in part that which the aforementioned authors expressed.
De Lapparent (1943), according to the figures given by various investigators, is of the opinion that the presence and disposition of the crenulations or denticles are not absolutely constant characters in all teeth of the same individual, and that these variations could correspond to the position on the mandible, which clearly is impossible to appreciate when isolated teeth are presented.
Commentary
The name Dinosauria was coined by Richard Owen in 1841 in his Report on British Fossil Reptiles (p. 103), in which he wrote regarding these reptiles: \\\"However, the combination of such characters, some, as the sacral ones, altogether peculiar among Reptiles, others borrowed, as it were, from groups now distinct from each other, and all manifested by creatures far surpassing in size the largest of existing reptiles, will, it is presumed, be deemed sufficient ground for establishing a distinct tribe or suborder of Saurian Reptiles, for which I would propose the name of Dinosauria.\\\" \\\"Of this tribe the principal and best established genera are the Megalosaurus, the Hylaeosaurus, and the Iguanodon...\\\".
The megalosaurids were large and heavy theropods, with a relatively large skull, compressed teeth with serrated edges, and a long lower jaw. The relatively short forelimbs bore digits with long, curved claws, the hindlimbs had the femur longer than the tibia and feet with functional digits.
According to Smith Woodward (1910), all megalosaur skulls are quite similar and it is difficult to find generic differences among them; they could hardly be distinguished except by the number and disposition of their premaxillary teeth, which seem to be constant in each genus.
According to Deperet & Savornin (1927), towards the middle of the tooth row, above and below, one or perhaps several teeth notably longer than the others and with the functional role of canines are found in megalosaurids, to which these investigators gave the name \\\"caniniform teeth\\\".
The other teeth, considerably shorter and less posteriorly curved, are still not entirely free from the alveoli and in this state have the role of incisors and molars. Depéret and Savornin designated them with the name \\\"alveolar teeth\\\". The megalosaurid family debúted in the Infra-Lias of Mosela, represented by a small species described by Terquen and P. Gervais, but lacking a specific name.
The family continues into the Lias of Lyme Regis (England) and is more abundant in the Lower Jurassic. According to Deperet & Savornin (op. cit.), the type of the genus is the species Megalosaurus bucklandii Meyer 1832, found in the lower Bathonian of Stonesfield, but it soon existed in the Inferior Oolite of Bridport and next in the Great Oolite and in the Forest Marble (upper Bathonian).
In the Upper Jurassic, megalosaurids are entirely represented by teeth, and have been indicated in England and the north of France. The remains of these dinosaurs are found in almost the entire thickness of Cretaceous terrains. From the Wealdian of Hanover, Koken in 1887 made known Megalosaurus dunkeri, with smaller teeth than Megalosaurus bucklandii.
Megalosaurids were discovered in the Albian of the Paris Basin, described by Sauvage in 1882, and were named Megalosaurus superbus (1), although it is more probable that this species pertains to a different genus than the Bathonian Megalosaurus and is closer—but not identical—to Dryptosaurus Marsh from the Greensand, New Egypt Formation, Glouchester County, New Jersey, US. The caniniform tooth of Megalosaurus superbus (1) Sauvageis stronger than that of Megalosaurus bucklandii and the anterior edge is serrated along its entire length. Ch. Depéret in 1896 made known from the Upper Cretaceous of the west coast of Madagascar, Mevarana, Megalosaurus crenatissimus, a form whose have a more recurved point in the posterior part, and edges with denticles along their entire lengths as in Megalosaurus superbus (1). The describer made evident the affinities with the North American genus Dryptosaurus. In 1881 Seeley described Megalosaurus pannoiensis from the Senonian of Austria.
Megalosaurids continue almost up to the end of the Cretaceous, as indicated by the case of Megalosaurus bredai (2) Seeley 1883, based on a femur found in the Upper Cretaceous of Maastricht, The Netherlands. (Maastrichtian).
The results of this is that the megalosaurid family of carnosaurs extended from the Rhaetian to the Maastrichtian. Deperet & Savornin (op. cit., p. 263) asked whether it was a single phyletic branch, with progressive and continual evolution. The solution of this problem is more delicate because most of the described species, except those from the Middle and Lower Jurassic, are founded only on isolated teeth, and their skeletal characters are very poorly known. And a great danger exists in founding affiliations on the consideration of a single structure.
This is evident in the case of carnosaur teeth, but the tooth of M. chubutensis is brought to light with the objective of demonstrating that near the great sauropods of Patagonia and South America lived great bipedal reptiles that preyed on them. In all parts of the world the remains of carnosaurs are scarce enough relative to herbivorous sauropods, but, as is known, there is a biological law that regulates the equilibrium of the fauna; the paucity of carnosaurian remains in our Cretaceous is an enigma when faced with the great quantity of sauropod remains found.
Source: Polyglot Paleontologist
Corro, 1974
Time
Cretaceous Late
Classification
Saurischia Theropoda Incertae Sedis \\\"Carnosaurs\\\" Nomina Dubia
Diet
Carnivore
Fossilsite
Cerro Castillo Formation, Provincia de Chubut, Argentina
Info
Tooth.
Corro del, (1999) \\\"Un nuevo megalosaurio (carnosaurio) del Cretacico de Chubut (Argentina)\\\". Paleontology Volume I, no. 5 Communicationes del Museo Argentino de Ciencias Naturales \\\"Bernardino Rivadavia e Instituto Nacional de Investigacion de las Ciencas Naturales. Director Jose Maria Gallardo [ A new megolosaur (Carnosaur) from the Cretaceous of Chubit (Argentina)
Translated by Matthew Carrano Department of Anatomical Sciences SUNY at Stony Brook April 1999
Introduction
This is the study of a tooth from a carnosaur of great size that was discovered by Drs. Ferello and Flores, geologists from the Yacimientos Petrolíferos Fiscales, in the course of the 1949 campaign in the province of Chubut. The tooth, which was given to the Museum, was found together with large bones that for obvious reasons were not extracted.
Order Saurischia
Suborder Theropoda
Infraorder Carnosauria
Family Megalosauridae Huxley 1870
Genus Megalosaurus Buckland 18241
1 F. von Huene (1956) said Megalosaurus Cuvier; Romer (1956) Megalosaurus Buckland 1822; Walker (1964), Megalosaurus Parkinson 1822, Lapparent and Lavocat in Piveteau, Traité de Paléontologie, V. 1955, gave Megalosaurus Buckland, 1824. von Huene in his Megalosaurus chubutensis nov. sp. Type. No. 18.189 Mus. Arg. C. Nat. \\\"B. Rivadavia\\\". Cat. Pal. Vert.
Description
Incomplete caniniform tooth, worn at the point, of large size, robust, and curved. The tooth in itself is not very well preserved. Its edges are sharp with very fine denticles, which generally are attentuated towards the apex in megalosaurids. The anterior part (convex) bears denticles that stop approximately 1 cm from the base, in contrast to the posterior part (concave) which bears denticles along the entire length of its edge.
The posterior face of the tooth is fairly convex, in contrast the anterior is nearly flat towards the posterior border. The surface of this caniniform2 tooth is polished, in parts showing enamel that is very finely striated in the vertical direction. The slightly concave undulations towards the point as seen in Megalosaurus saharicus Deperet& Savornin, 1927 and in Megalosaurus inexpectatus del Corro are not distinguished. Its aspect recalls the tooth of Megalosaurus insignis Eudes-Deslongchamps & Lennier, 1870, figured by de Lapparent (1943, pl. 1, fig. 1). On the base the tooth has an oval shape.
Measurements
Preserved length, taken on the anterior side, 74mm. Total length calculated circa 85 mm Maximum thickness at the base 22 \\\" Maxmimum width 35 \\\"
Horizon and Age
Cerro Castillo Formation. Upper Member. Middle Chubutian (= Green Tufas of Feruglio). Possibly the upper part of the Lower Cretaceous, \\\"The carnivorous Saurischia in the Jura and Cretaceous formations, principally in Europe,\\\" Rev. Mus. La Plata v. 29, 1926 (p. 45) expressed that the first description was made in 1824 by W. Buckland in Trans. Geol. Soc. London, no. 21, with the title, \\\"Notice on the Megalosaurus or great fossil lizard of Stonesfield,\\\" and that the species Megalosaurus bucklandii was thus named by H. von Meyer in 1832.
2 De Lapparent (1943) (p. 11) said that it was named thus among the megalosaurids one or various teeth enough larger than the others, situated towards the middle of the tooth row, and that had the functional role of canines in eminently carnivorous animals.
3 Feruglio in \\\"Descripción Geológica de la Patagonia\\\" 1949, vol. 1 (p. 245), mentioning the diverse fossil reptiles of the Chubutensian or Chubutian, wrote: \\\"That end to mention are so only the more important discoveries, because fragments and chips of bone are found in most other points, on all within the Upper Section of the Chubutensian, although not lacking either below, for at least towards the section inclusive of the Green Tufas\\\".
4 According to oral communication of Dr. M. A. Flores of Y. P. F. Geographic locality. North of Cerro Crettón. Mallín Grade farm. Department of Sarmiento. Province of Chubut (Argentina).
Comparisons
The caniniform tooth of Megalosaurus chubutensis nov. sp., different in size, by its form typical of megalosaurids, resembles Megalosaurus insignis Eudes-Deslongchamps & Lennier, Megalosaurus pannoiensis Seeley and Megalosaurus inexpectatus del Corro by the denticles of the anterior border, which end on its lower third; it differs from Megalosaurus superbus (1) Sauvage, Megalosaurus crenatissimus Deperet and Megalosaurus saharicus Deperet & Savornin by having denticles along the lengths of both sharp edges, from [Dryptosaurus medius] (Marsh) because these teeth also bear crenulations on both edges. Likewise Megalosaurus saharicus shows a series of concentric undulations on the tooth faces that are similar to those presented by Megalosaurus inexpectatus and that are not seen in the aforementioned species.
Considerations
Deperet & Savornin (1927:263) expressed that considering only the tooth characters, a series of \\\"continuous mutations\\\" could be conceived according to the disposition of the denticles on the sharp edges of the teeth. Meanwhile in all the species these denticles extend along the entire extent of the posterior edge, whereas they are limited to the upper third of the anterior edge in older species such as Megalosaurus bucklandii (Middle Jurassic), and are extended onto the upper half of this edge in more recent forms such as Streptospondylus cuvieri from the Oxfordian, Megalosaurus insignis (Kimmeridgian and Portlandian),
Megalosaurus dunkeri (Upper Jurassic, Purbeckian and Lower Cretaceous, Wealdian); in the Upper Cretaceous species such as Megalosaurus superbus (1) of the Albian and Megalosaurus crenatissimus of the Turonian (lower part of the Upper Cretaceous), the denticles are finer and extend along the entire anterior edge. Without doubt this is neither the case with Megalosaurus chubutensis (probably upper part of the Lower Cretaceous–Cenomanian or Turonian) nor Megalosaurus inexpectatus (Senonian–Upper Cretaceous), wherein as already noted the crenulations do not extend along the entire anterior face.
Likewise, in Megalosaurus insignis (Upper Jurassic) the crenulations of the anterior side begin or leave off slowly, in M. chubutensis the denticles are robust and begin or leave off almost brusquely, whereas in Megalosaurus inexpectatus the crenulations begin or leave off as in Megalosaurus insignis and are finer. This weakens in part that which the aforementioned authors expressed.
De Lapparent (1943), according to the figures given by various investigators, is of the opinion that the presence and disposition of the crenulations or denticles are not absolutely constant characters in all teeth of the same individual, and that these variations could correspond to the position on the mandible, which clearly is impossible to appreciate when isolated teeth are presented.
Commentary
The name Dinosauria was coined by Richard Owen in 1841 in his Report on British Fossil Reptiles (p. 103), in which he wrote regarding these reptiles: \\\"However, the combination of such characters, some, as the sacral ones, altogether peculiar among Reptiles, others borrowed, as it were, from groups now distinct from each other, and all manifested by creatures far surpassing in size the largest of existing reptiles, will, it is presumed, be deemed sufficient ground for establishing a distinct tribe or suborder of Saurian Reptiles, for which I would propose the name of Dinosauria.\\\" \\\"Of this tribe the principal and best established genera are the Megalosaurus, the Hylaeosaurus, and the Iguanodon...\\\".
The megalosaurids were large and heavy theropods, with a relatively large skull, compressed teeth with serrated edges, and a long lower jaw. The relatively short forelimbs bore digits with long, curved claws, the hindlimbs had the femur longer than the tibia and feet with functional digits.
According to Smith Woodward (1910), all megalosaur skulls are quite similar and it is difficult to find generic differences among them; they could hardly be distinguished except by the number and disposition of their premaxillary teeth, which seem to be constant in each genus.
According to Deperet & Savornin (1927), towards the middle of the tooth row, above and below, one or perhaps several teeth notably longer than the others and with the functional role of canines are found in megalosaurids, to which these investigators gave the name \\\"caniniform teeth\\\".
The other teeth, considerably shorter and less posteriorly curved, are still not entirely free from the alveoli and in this state have the role of incisors and molars. Depéret and Savornin designated them with the name \\\"alveolar teeth\\\". The megalosaurid family debúted in the Infra-Lias of Mosela, represented by a small species described by Terquen and P. Gervais, but lacking a specific name.
The family continues into the Lias of Lyme Regis (England) and is more abundant in the Lower Jurassic. According to Deperet & Savornin (op. cit.), the type of the genus is the species Megalosaurus bucklandii Meyer 1832, found in the lower Bathonian of Stonesfield, but it soon existed in the Inferior Oolite of Bridport and next in the Great Oolite and in the Forest Marble (upper Bathonian).
In the Upper Jurassic, megalosaurids are entirely represented by teeth, and have been indicated in England and the north of France. The remains of these dinosaurs are found in almost the entire thickness of Cretaceous terrains. From the Wealdian of Hanover, Koken in 1887 made known Megalosaurus dunkeri, with smaller teeth than Megalosaurus bucklandii.
Megalosaurids were discovered in the Albian of the Paris Basin, described by Sauvage in 1882, and were named Megalosaurus superbus (1), although it is more probable that this species pertains to a different genus than the Bathonian Megalosaurus and is closer—but not identical—to Dryptosaurus Marsh from the Greensand, New Egypt Formation, Glouchester County, New Jersey, US. The caniniform tooth of Megalosaurus superbus (1) Sauvageis stronger than that of Megalosaurus bucklandii and the anterior edge is serrated along its entire length. Ch. Depéret in 1896 made known from the Upper Cretaceous of the west coast of Madagascar, Mevarana, Megalosaurus crenatissimus, a form whose have a more recurved point in the posterior part, and edges with denticles along their entire lengths as in Megalosaurus superbus (1). The describer made evident the affinities with the North American genus Dryptosaurus. In 1881 Seeley described Megalosaurus pannoiensis from the Senonian of Austria.
Megalosaurids continue almost up to the end of the Cretaceous, as indicated by the case of Megalosaurus bredai (2) Seeley 1883, based on a femur found in the Upper Cretaceous of Maastricht, The Netherlands. (Maastrichtian).
The results of this is that the megalosaurid family of carnosaurs extended from the Rhaetian to the Maastrichtian. Deperet & Savornin (op. cit., p. 263) asked whether it was a single phyletic branch, with progressive and continual evolution. The solution of this problem is more delicate because most of the described species, except those from the Middle and Lower Jurassic, are founded only on isolated teeth, and their skeletal characters are very poorly known. And a great danger exists in founding affiliations on the consideration of a single structure.
This is evident in the case of carnosaur teeth, but the tooth of M. chubutensis is brought to light with the objective of demonstrating that near the great sauropods of Patagonia and South America lived great bipedal reptiles that preyed on them. In all parts of the world the remains of carnosaurs are scarce enough relative to herbivorous sauropods, but, as is known, there is a biological law that regulates the equilibrium of the fauna; the paucity of carnosaurian remains in our Cretaceous is an enigma when faced with the great quantity of sauropod remains found.
Source: Polyglot Paleontologist