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Jürgen Kriwet - One of the best experts on this subject based on the ideXlab platform.
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micro computed tomography imaging reveals the development of a unique tooth mineralization pattern in mackerel sharks chondrichthyes Lamniformes in deep time
Scientific Reports, 2019Co-Authors: Patrick L Jambura, Giuseppe Marrama, Cathrin Pfaff, Rene Kindlimann, Faviel A Lopezromero, Sebastian Stumpf, Julia Turtscher, Charlie J Underwood, David J Ward, Jürgen KriwetAbstract:The cartilaginous fishes (Chondrichthyes) have a rich fossil record which consists mostly of isolated teeth and, therefore, phylogenetic relationships of extinct taxa are mainly resolved based on dental characters. One character, the tooth histology, has been examined since the 19th century, but its implications on the phylogeny of Chondrichthyes is still in debate. We used high resolution micro-CT images and tooth sections of 11 recent and seven extinct lamniform sharks to examine the tooth mineralization processes in this group. Our data showed similarities between lamniform sharks and other taxa (a dentinal core of osteodentine instead of a hollow pulp cavity), but also one feature that has not been known from any other elasmobranch fish: the absence of orthodentine. Our results suggest that this character resembles a synapomorphic condition for lamniform sharks, with the basking shark, Cetorhinus maximus, representing the only exception and reverted to the plesiomorphic tooth histotype. Additionally, †Palaeocarcharias stromeri, whose affiliation still is debated, shares the same tooth histology only known from lamniform sharks. This suggests that †Palaeocarcharias stromeri is member of the order Lamniformes, contradicting recent interpretations and thus, dating the origin of this group back at least into the Middle Jurassic.
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a synoptic review of the eocene ypresian cartilaginous fishes chondrichthyes holocephali elasmobranchii of the bolca konservat lagerstatte italy
Palaeontologische Zeitschrift, 2018Co-Authors: Giuseppe Marrama, Andrea Engelbrecht, Mariagabriella Fornasiero, Roberto Zorzin, Kerin M Claeson, Giorgio Carnevale, Jürgen KriwetAbstract:Here, we review and discuss the records and taxonomy of the Ypresian (Eocene) chondrichthyans from the famous Bolca Konservat-Lagerstatte in northeastern Italy. Despite the outstanding diversity and the numerous studies focusing on the actinopterygian faunas from Pesciara and Monte Postale, the current knowledge about the systematics, taxonomy and phylogenetic relationships of the cartilaginous fishes from these Eocene sites remains elusive and largely inadequate. The celebrated Eocene Bolca Lagerstatte has yielded several exquisitely preserved articulated remains of chondrichthyan fishes in which delicate structures and soft tissues are preserved, as well as isolated teeth. The cartilaginous fish assemblage of Bolca comprises at least 17 species-level taxa belonging to 10 families in 6 orders, including selachians (Carcharhiniformes, Lamniformes), batoids (Torpediniformes, Myliobatiformes, Rajiformes) and holocephalans (Chimaeriformes). The occurrence of holocephalans represented by an isolated fin-spine of the chimeroid Ischyodus in the Bolca assemblage is reported here for the first time and represents the first record of chimeroids in the Eocene of Italy and also southern Europe. The Bolca chondrichthyan assemblage is remarkably different from those of other contemporaneous Boreal or Tethyan deposits, suggesting that its taxonomic composition is largely influenced by the palaeoenvironmental context. However, this synoptic review also highlights the importance of detailed revisions of all chondrichthyan remains from the Bolca Konservat-Lagerstatten.
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A synoptic review of the Eocene (Ypresian) cartilaginous fishes (Chondrichthyes: Holocephali, Elasmobranchii) of the Bolca Konservat-Lagerstätte, Italy
PalZ, 2018Co-Authors: Giuseppe Marrama, Andrea Engelbrecht, Mariagabriella Fornasiero, Roberto Zorzin, Kerin M Claeson, Giorgio Carnevale, Jürgen KriwetAbstract:Obwohl Knochenfische in der berühmten eozänen (Ypresium) Bolca-Konservatlagerstätte in NE-Italien äußerst divers sind und in den vergangenen Jahren Gegenstand zahlreicher Studien waren, ist der derzeitige Kenntnisstand über die Systematik, Taxonomie und Phylogenie der Knorpelfische aus dieser Lagerstätte überraschend gering und ungenau. In dieser Studie geben wir einen Überblick über die Knorpelfische der Bolca-Konservatlagerstätte und diskutieren ihre Verbreitung und ihre Taxonomie. Aus den beiden Fundstellen Pesciara und Monte Postale stammen einige sehr gut erhaltene Exemplare, bei denen auch sehr feine Strukturen und Weichgewebe fossilisiert sind, sowie isolierte Zähne. Die Knorpelfischfauna von Bolca umfasst mindestens 17 Arten, die zu zehn Familien und sechs Ordnungen gehören wie Haie (Carcharhiniformes, Lamniformes), Rochen (Torpediniformes, Myliobatiformes, Rajiformes) und Chimären. Chimären sind erstmals für Bolca durch einen isolierten Flossenstachel von Ischyodus belegt, was gleichzeitig der erste Nachweis für Chimären im Eozän von Italien und Süd-Europa ist. Die Knorpelfischassoziation von Bolca unterscheidet sich in ihrer taxonomischen Zusammensetzung auffällig von anderen tethyalen und auch borealen Faunen. Dies lässt vermuten, dass die taxonomische Zusammensetzung im Wesentlichen durch Umweltbedingungen bestimmt ist. Der hier präsentierte synoptische Überblick der Bolca-Knorpelfische zeigt aber auch deutlich, dass detaillierte Revisionen aller Knorpelfischreste der Bolca-Konservatlagerstätte für ein besseres Verständnis dieser wichtigen eozänen Fundstelle dringend nötig sind. Here, we review and discuss the records and taxonomy of the Ypresian (Eocene) chondrichthyans from the famous Bolca Konservat-Lagerstätte in northeastern Italy. Despite the outstanding diversity and the numerous studies focusing on the actinopterygian faunas from Pesciara and Monte Postale, the current knowledge about the systematics, taxonomy and phylogenetic relationships of the cartilaginous fishes from these Eocene sites remains elusive and largely inadequate. The celebrated Eocene Bolca Lagerstätte has yielded several exquisitely preserved articulated remains of chondrichthyan fishes in which delicate structures and soft tissues are preserved, as well as isolated teeth. The cartilaginous fish assemblage of Bolca comprises at least 17 species-level taxa belonging to 10 families in 6 orders, including selachians (Carcharhiniformes, Lamniformes), batoids (Torpediniformes, Myliobatiformes, Rajiformes) and holocephalans (Chimaeriformes). The occurrence of holocephalans represented by an isolated fin-spine of the chimeroid Ischyodus in the Bolca assemblage is reported here for the first time and represents the first record of chimeroids in the Eocene of Italy and also southern Europe. The Bolca chondrichthyan assemblage is remarkably different from those of other contemporaneous Boreal or Tethyan deposits, suggesting that its taxonomic composition is largely influenced by the palaeoenvironmental context. However, this synoptic review also highlights the importance of detailed revisions of all chondrichthyan remains from the Bolca Konservat-Lagerstätten.
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the southernmost occurrence of brachycarcharias Lamniformes odontaspididae from the eocene of antarctica provides new information about the paleobiogeography and paleobiology of paleogene sand tiger sharks
Rivista Italiana Di Paleontologia E Stratigrafia, 2018Co-Authors: Giuseppe Marrama, Andrea Engelbrecht, Marcelo Reguero, Thomas Mors, Jürgen KriwetAbstract:The first record of one of the most common and widespread Paleogene selachians, the sand tiger shark Brachycarcharias , in the Ypresian strata of the La Meseta Formation, Seymour Island, Antarctica, is provided herein. Selachians from the early Eocene horizons of this deposit represent the southernmost Paleogene occurrences in the fossil record, and are represented by isolated teeth belonging to orectolobiforms, lamniforms, carcharhiniforms, squatiniforms and pristiophoriforms. The combination of dental characters of the 49 isolated teeth collected from the horizons TELMs 2, 4 and 5 supports their assignment to the odontaspidid Brachycarcharias lerichei (Casier, 1946), a lamniform species widely spread across the Northern Hemisphere during the early Paleogene. The unambiguous first report of this lamniform shark in the Southern Hemisphere in the Eocene of the La Meseta Formation improves our knowledge concerning the diversity and paleobiology of the cartilaginous fishes of this deposit, and provides new insights about the biotic turnovers that involved the high trophic levels of the marine settings after the end-Cretaceous extinction and before the establishment of the modern marine ecosystems.
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Eocene sand tiger sharks (Lamniformes, Odontaspididae) from the Bolca Konservat-Lagerstätte, Italy: palaeobiology, palaeobiogeography and evolutionary significance
Historical Biology, 2017Co-Authors: Giuseppe Marrama, Andrea Engelbrecht, Giorgio Carnevale, Jürgen KriwetAbstract:AbstractHere we report the first record of one of the most common and widespread Palaeogene selachians, the sand tiger shark Brachycarcharias, from the Ypresian Bolca Konservat-Lagerstatte. The combination of dental character of the 15 isolated teeth collected from the Pesciara and Monte Postale sites (e.g. anterior teeth up to 25 mm with fairly low triangular cusp decreasing regularly in width; one to two pairs of well-developed lateral cusplets; root with broadly separated lobes; upper teeth with a cusp bent distally) supports their assignment to the odontaspidid Brachycarcharias lerichei (Casier, 1946), a species widely spread across the North Hemisphere during the early Palaeogene. The unambiguous first report of this lamniform shark in the Eocene Bolca Konservat-Lagerstatte improves our knowledge concerning the diversity and palaeobiology of the cartilaginous fishes of this palaeontological site, and provides new insights about the biotic turnovers that involved the high trophic levels of the marine ...
Kenshu Shimada - One of the best experts on this subject based on the ideXlab platform.
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Integument-based inferences on the swimming ability and prey hunting strategy of the bigeye thresher shark, Alopias superciliosus (Lamniformes: Alopiidae)
Zoomorphology, 2020Co-Authors: Joseph A. Frumkin, Kenshu ShimadaAbstract:Alopias is a group of lamniform sharks characterized by a highly elongate caudal fin with three known extant species: Alopias pelagicus (pelagic thresher shark), Alopias superciliosus (bigeye thresher shark), and Alopias vulpinus (common thresher shark). Alopias pelagicus and A. vulpinus are considered fast swimmers and use their caudal fin to hunt for small schooling fish by stunning them, but this feeding behavior has never been directly observed for A. superciliosus . In this study, we examined four integumentary variables of selected fast swimming (e.g. A. pelagicus , A. vulpinus , and Lamna ) and slow swimming (e.g. Mitsukurina and Megachasma ) lamniform sharks to determine whether A. superciliosus is a fast swimmer or a slow swimmer. Our data indicate that A. superciliosus is a slow swimming lamniform, but it probably employs a simple laterally directed tail slap to capture its prey. Overall, our study points to an interpretation that A. superciliosus is an ambush predator, rather than an active prey-pursuing hunter. Mapping of scale data onto previously published phylogenetic trees indicate that slow swimming is a plesiomorphic condition in the order Lamniformes. Our work represents the most extensive comparative study of the morphology and variation of integumentary structures, especially placoid scales, conducted so far for Lamniformes.
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skeletal anatomy of the bigeye sand tiger shark odontaspis noronhai Lamniformes odontaspididae and its implications for lamniform phylogeny taxonomy and conservation biology
Copeia, 2019Co-Authors: Nicholas R Stone, Kenshu ShimadaAbstract:Lamniformes (Chondrichthyes: Elasmobranchii) is a group of sharks that consists of 15 extant species with a wide range of morphological diversity. The most rarely captured lamniform is Odontaspis n...
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the size of the megatooth shark otodus megalodon Lamniformes otodontidae revisited
Historical Biology, 2019Co-Authors: Kenshu ShimadaAbstract:ABSTRACTOtodus megalodon (Lamniformes: Otodontidae) is a gigantic late Neogene shark that lived nearly worldwide in tropical-temperate regions. Its gigantic teeth have captivated imaginations of th...
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a new elusive otodontid shark Lamniformes otodontidae from the lower miocene and comments on the taxonomy of otodontid genera including the megatoothed clade
Historical Biology, 2017Co-Authors: Kenshu Shimada, Richard E Chandler, Takeshi Tanaka, David WardAbstract:AbstractWe describe a new large otodontid lamniform shark, Megalolamna paradoxodon gen. nov. et sp. nov., chronostratigraphically restricted to the early Miocene (Aquitanian–Burdigalian). This new species is based on isolated teeth found from five globally distributed localities: the Jewett Sand in southern California, USA; the Pungo River Formation of North Carolina, USA; the Chilcatay Formation of Peru; the Oi Formation in Mie Prefecture, Japan; and the O’oshimojo Formation in Nagano Prefecture, Japan. Extrapolations based on available published data on modern macrophagous lamniforms suggest that the largest specimen of M. paradoxodon gen. nov. et sp. nov. possibly came from an individual that measured at least 3.7 m in total length. All specimens came from deposits in the mid-latitudinal zones representing shallow-water, shelf-type, coastal environments. Its dentition likely exhibited monognathic heterodonty suited for capturing and cutting relatively large prey (e.g. medium-sized fishes). We recommend...
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The Oldest Fossil Record of the Megamouth Shark from the Late Eocene of Denmark and Comments on the Enigmatic Megachasmid Origin
Acta Palaeontologica Polonica, 2016Co-Authors: Kenshu Shimada, David WardAbstract:The megamouth shark (Lamniformes: Megachasmidae) has sporadic occurrences both in the present-day oceans and in the fossil record. In this paper, we describe a new megachasmid, Megachasma alisonae sp. nov., on the basis of a morphologically distinct tooth collected from the Pyt Member of the late Eocene Sovind Marl Formation at Moesgard Strand in Denmark, that represents the geologically oldest known Megachasma. The tooth likely came from an individual that measured somewhere between 1.3 and 3.5 m long, and its morphology and chipped cusp tips suggest that it possibly fed on macro-zooplankton and small fishes that had hard skeletal components. Its occurrence in the mid-Priabonian Pyt Member at least suggests that the shark inhabited a relatively deep, open marine environment about 36 Ma ago. This Eocene specimen is significant because it illustrates the dental condition of early megachasmids, which is distinctively odontaspidid-like morphologically.
Giuseppe Marrama - One of the best experts on this subject based on the ideXlab platform.
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micro computed tomography imaging reveals the development of a unique tooth mineralization pattern in mackerel sharks chondrichthyes Lamniformes in deep time
Scientific Reports, 2019Co-Authors: Patrick L Jambura, Giuseppe Marrama, Cathrin Pfaff, Rene Kindlimann, Faviel A Lopezromero, Sebastian Stumpf, Julia Turtscher, Charlie J Underwood, David J Ward, Jürgen KriwetAbstract:The cartilaginous fishes (Chondrichthyes) have a rich fossil record which consists mostly of isolated teeth and, therefore, phylogenetic relationships of extinct taxa are mainly resolved based on dental characters. One character, the tooth histology, has been examined since the 19th century, but its implications on the phylogeny of Chondrichthyes is still in debate. We used high resolution micro-CT images and tooth sections of 11 recent and seven extinct lamniform sharks to examine the tooth mineralization processes in this group. Our data showed similarities between lamniform sharks and other taxa (a dentinal core of osteodentine instead of a hollow pulp cavity), but also one feature that has not been known from any other elasmobranch fish: the absence of orthodentine. Our results suggest that this character resembles a synapomorphic condition for lamniform sharks, with the basking shark, Cetorhinus maximus, representing the only exception and reverted to the plesiomorphic tooth histotype. Additionally, †Palaeocarcharias stromeri, whose affiliation still is debated, shares the same tooth histology only known from lamniform sharks. This suggests that †Palaeocarcharias stromeri is member of the order Lamniformes, contradicting recent interpretations and thus, dating the origin of this group back at least into the Middle Jurassic.
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a synoptic review of the eocene ypresian cartilaginous fishes chondrichthyes holocephali elasmobranchii of the bolca konservat lagerstatte italy
Palaeontologische Zeitschrift, 2018Co-Authors: Giuseppe Marrama, Andrea Engelbrecht, Mariagabriella Fornasiero, Roberto Zorzin, Kerin M Claeson, Giorgio Carnevale, Jürgen KriwetAbstract:Here, we review and discuss the records and taxonomy of the Ypresian (Eocene) chondrichthyans from the famous Bolca Konservat-Lagerstatte in northeastern Italy. Despite the outstanding diversity and the numerous studies focusing on the actinopterygian faunas from Pesciara and Monte Postale, the current knowledge about the systematics, taxonomy and phylogenetic relationships of the cartilaginous fishes from these Eocene sites remains elusive and largely inadequate. The celebrated Eocene Bolca Lagerstatte has yielded several exquisitely preserved articulated remains of chondrichthyan fishes in which delicate structures and soft tissues are preserved, as well as isolated teeth. The cartilaginous fish assemblage of Bolca comprises at least 17 species-level taxa belonging to 10 families in 6 orders, including selachians (Carcharhiniformes, Lamniformes), batoids (Torpediniformes, Myliobatiformes, Rajiformes) and holocephalans (Chimaeriformes). The occurrence of holocephalans represented by an isolated fin-spine of the chimeroid Ischyodus in the Bolca assemblage is reported here for the first time and represents the first record of chimeroids in the Eocene of Italy and also southern Europe. The Bolca chondrichthyan assemblage is remarkably different from those of other contemporaneous Boreal or Tethyan deposits, suggesting that its taxonomic composition is largely influenced by the palaeoenvironmental context. However, this synoptic review also highlights the importance of detailed revisions of all chondrichthyan remains from the Bolca Konservat-Lagerstatten.
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A synoptic review of the Eocene (Ypresian) cartilaginous fishes (Chondrichthyes: Holocephali, Elasmobranchii) of the Bolca Konservat-Lagerstätte, Italy
PalZ, 2018Co-Authors: Giuseppe Marrama, Andrea Engelbrecht, Mariagabriella Fornasiero, Roberto Zorzin, Kerin M Claeson, Giorgio Carnevale, Jürgen KriwetAbstract:Obwohl Knochenfische in der berühmten eozänen (Ypresium) Bolca-Konservatlagerstätte in NE-Italien äußerst divers sind und in den vergangenen Jahren Gegenstand zahlreicher Studien waren, ist der derzeitige Kenntnisstand über die Systematik, Taxonomie und Phylogenie der Knorpelfische aus dieser Lagerstätte überraschend gering und ungenau. In dieser Studie geben wir einen Überblick über die Knorpelfische der Bolca-Konservatlagerstätte und diskutieren ihre Verbreitung und ihre Taxonomie. Aus den beiden Fundstellen Pesciara und Monte Postale stammen einige sehr gut erhaltene Exemplare, bei denen auch sehr feine Strukturen und Weichgewebe fossilisiert sind, sowie isolierte Zähne. Die Knorpelfischfauna von Bolca umfasst mindestens 17 Arten, die zu zehn Familien und sechs Ordnungen gehören wie Haie (Carcharhiniformes, Lamniformes), Rochen (Torpediniformes, Myliobatiformes, Rajiformes) und Chimären. Chimären sind erstmals für Bolca durch einen isolierten Flossenstachel von Ischyodus belegt, was gleichzeitig der erste Nachweis für Chimären im Eozän von Italien und Süd-Europa ist. Die Knorpelfischassoziation von Bolca unterscheidet sich in ihrer taxonomischen Zusammensetzung auffällig von anderen tethyalen und auch borealen Faunen. Dies lässt vermuten, dass die taxonomische Zusammensetzung im Wesentlichen durch Umweltbedingungen bestimmt ist. Der hier präsentierte synoptische Überblick der Bolca-Knorpelfische zeigt aber auch deutlich, dass detaillierte Revisionen aller Knorpelfischreste der Bolca-Konservatlagerstätte für ein besseres Verständnis dieser wichtigen eozänen Fundstelle dringend nötig sind. Here, we review and discuss the records and taxonomy of the Ypresian (Eocene) chondrichthyans from the famous Bolca Konservat-Lagerstätte in northeastern Italy. Despite the outstanding diversity and the numerous studies focusing on the actinopterygian faunas from Pesciara and Monte Postale, the current knowledge about the systematics, taxonomy and phylogenetic relationships of the cartilaginous fishes from these Eocene sites remains elusive and largely inadequate. The celebrated Eocene Bolca Lagerstätte has yielded several exquisitely preserved articulated remains of chondrichthyan fishes in which delicate structures and soft tissues are preserved, as well as isolated teeth. The cartilaginous fish assemblage of Bolca comprises at least 17 species-level taxa belonging to 10 families in 6 orders, including selachians (Carcharhiniformes, Lamniformes), batoids (Torpediniformes, Myliobatiformes, Rajiformes) and holocephalans (Chimaeriformes). The occurrence of holocephalans represented by an isolated fin-spine of the chimeroid Ischyodus in the Bolca assemblage is reported here for the first time and represents the first record of chimeroids in the Eocene of Italy and also southern Europe. The Bolca chondrichthyan assemblage is remarkably different from those of other contemporaneous Boreal or Tethyan deposits, suggesting that its taxonomic composition is largely influenced by the palaeoenvironmental context. However, this synoptic review also highlights the importance of detailed revisions of all chondrichthyan remains from the Bolca Konservat-Lagerstätten.
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the southernmost occurrence of brachycarcharias Lamniformes odontaspididae from the eocene of antarctica provides new information about the paleobiogeography and paleobiology of paleogene sand tiger sharks
Rivista Italiana Di Paleontologia E Stratigrafia, 2018Co-Authors: Giuseppe Marrama, Andrea Engelbrecht, Marcelo Reguero, Thomas Mors, Jürgen KriwetAbstract:The first record of one of the most common and widespread Paleogene selachians, the sand tiger shark Brachycarcharias , in the Ypresian strata of the La Meseta Formation, Seymour Island, Antarctica, is provided herein. Selachians from the early Eocene horizons of this deposit represent the southernmost Paleogene occurrences in the fossil record, and are represented by isolated teeth belonging to orectolobiforms, lamniforms, carcharhiniforms, squatiniforms and pristiophoriforms. The combination of dental characters of the 49 isolated teeth collected from the horizons TELMs 2, 4 and 5 supports their assignment to the odontaspidid Brachycarcharias lerichei (Casier, 1946), a lamniform species widely spread across the Northern Hemisphere during the early Paleogene. The unambiguous first report of this lamniform shark in the Southern Hemisphere in the Eocene of the La Meseta Formation improves our knowledge concerning the diversity and paleobiology of the cartilaginous fishes of this deposit, and provides new insights about the biotic turnovers that involved the high trophic levels of the marine settings after the end-Cretaceous extinction and before the establishment of the modern marine ecosystems.
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Eocene sand tiger sharks (Lamniformes, Odontaspididae) from the Bolca Konservat-Lagerstätte, Italy: palaeobiology, palaeobiogeography and evolutionary significance
Historical Biology, 2017Co-Authors: Giuseppe Marrama, Andrea Engelbrecht, Giorgio Carnevale, Jürgen KriwetAbstract:AbstractHere we report the first record of one of the most common and widespread Palaeogene selachians, the sand tiger shark Brachycarcharias, from the Ypresian Bolca Konservat-Lagerstatte. The combination of dental character of the 15 isolated teeth collected from the Pesciara and Monte Postale sites (e.g. anterior teeth up to 25 mm with fairly low triangular cusp decreasing regularly in width; one to two pairs of well-developed lateral cusplets; root with broadly separated lobes; upper teeth with a cusp bent distally) supports their assignment to the odontaspidid Brachycarcharias lerichei (Casier, 1946), a species widely spread across the North Hemisphere during the early Palaeogene. The unambiguous first report of this lamniform shark in the Eocene Bolca Konservat-Lagerstatte improves our knowledge concerning the diversity and palaeobiology of the cartilaginous fishes of this palaeontological site, and provides new insights about the biotic turnovers that involved the high trophic levels of the marine ...
Dana J Ehret - One of the best experts on this subject based on the ideXlab platform.
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a new species of cretalamna sensu stricto Lamniformes otodontidae from the late cretaceous santonian campanian of alabama usa
PeerJ, 2018Co-Authors: Jun A Ebersole, Dana J EhretAbstract:: Decades of collecting from exposures of the Upper Cretaceous Tombigbee Sand Member of the Eutaw Formation and Mooreville Chalk in Alabama, USA has produced large numbers of isolated Cretalamna (sensu stricto) teeth. Many of these teeth had formerly been assigned to the extinct Late Cretaceous shark Cretalamna appendiculata (Agassiz, 1843), a taxon that is now considered largely restricted to the Turonian of Europe. Recent studies have shed light on the diversity of Late Cretaceous Cretalamna (s.s.) taxa, and here we recognize a new species from Alabama, Cretalamna bryanti. The teeth of C. bryanti sp. nov. appear aligned with the members of the Cretalamna borealis species group, but can be distinguished from these other species by a combination of the following: anterior teeth with a more pronounced and triangular lingual root protuberance, broader triangular cusp, and a taller root relative to the height of the crown; anteriorly situated lateroposterior teeth have a distally inclined or hooked main cusp and more than one pair of lateral cusplets; and lateroposterior teeth have a strong distally hooked main cusp and a root that is largely symmetrical in basal view. At present, C. bryanti sp. nov. is stratigraphically confined to the Santonian/Campanian Dicarinella asymetrica Sigal, 1952 and Globotruncanita elevata Brotzen, 1934 Planktonic Foraminiferal Zones within the Tombigbee Sand Member of the Eutaw Formation and Mooreville Chalk, and teeth have been collected from only four counties in central and western Alabama. The recognition of C. bryanti sp. nov. in Alabama adds to our knowledge on the diversity and distribution of Late Cretaceous otodontids in the region.
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occurrence of the megatoothed sharks Lamniformes otodontidae in alabama usa
PeerJ, 2014Co-Authors: Dana J Ehret, Jun A EbersoleAbstract:: The Otodontidae include some of the largest sharks to ever live in the world's oceans (i.e., Carcharocles megalodon). Here we report on Paleocene and Eocene occurrences of Otodus obliquus and Carcharocles auriculatus from Alabama, USA. Teeth of Otodus are rarely encountered in the Gulf Coastal Plain and this report is one of the first records for Alabama. Carcharocles auriculatus is more common in the Eocene deposits of Alabama, but its occurrence has been largely overlooked in the literature. We also refute the occurrence of the Oligocene Carcharocles angustidens in the state. Raised awareness and increased collecting of under-sampled geologic formations in Alabama will likely increase sample sizes of O. obliquus and C. auriculatus and also might unearth other otodontids, such as C. megalodon and C. chubutensis.
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exceptional preservation of the white shark carcharodon Lamniformes lamnidae from the early pliocene of peru
Journal of Vertebrate Paleontology, 2009Co-Authors: Dana J Ehret, Gordon Hubbell, Bruce J MacfaddenAbstract:ABSTRACT An exceptionally well-preserved white shark fossil (Carcharodon sp.) is described here from the early Pliocene (ca. 4 Ma) Pisco Formation of southwestern Peru. This specimen preserves 222 teeth and 45 vertebrae as well as fragmentary jaws. The teeth show characters of Carcharodon, including weak serrations and a symmetrical first anterior tooth that is the largest in the tooth row. This dentition also shows a character of Isurus with a distally inclined but mesially slanted intermediate tooth. Although the Pisco specimen demonstrates characters of both Isurus, also known form the Pisco Formation, and modern Carcharodon carcharias, it is assigned to the genus Carcharodon and referred to herein as Carcharodon sp. While Carcharodon sp. From the Pisco Formation shows numerous diagnostic characteristics shared with C. carcharias, it differs from the extant species in having a distal inclination of the intermediate tooth. The precaudal vertebral centra of the Pisco Carcharodon preserve distinctive dark...
Patricio Barria - One of the best experts on this subject based on the ideXlab platform.
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alimentacion del tiburon marrajo isurus oxyrinchus rafinesque 1810 Lamniformes lamnidae en el pacifico suroriental
Revista De Biologia Marina Y Oceanografia, 2009Co-Authors: Sebastian Lopez, Roberto Melendez, Patricio BarriaAbstract:In order to examine the feeding of mako shark Isurus oxyrinchus, the stomach content of 205 specimens, captured between 21o and 35oS and 78o and 118o W off C...
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alimentacion del tiburon marrajo isurus oxyrinchus rafinesque 1810 Lamniformes lamnidae en el pacifico suroriental feeding of the shortfin mako shark isurus oxyrinchus rafinesque 1810 Lamniformes lamnidae in the southeastern pacific
2009Co-Authors: Sebastian Lopez, Roberto Melendez, Patricio BarriaAbstract:In order to examine the feeding of mako shark Isurus oxyrinchus, the stomach content of 205 specimens, captured between 21o and 35oS and 78o and 118o W off Chile, during 2005 and 2006 were analyzed. The 47.8% of the sharks had food in their stomachs. The numeric, frequency and weight methods and the index of relative importance (IIR) were used to describe their diet. The diet was compared between sexes and spatio-temporal variations of the diet were also determined. The diet of the mako shark consisted of 17 prey items. Teleost fishes were the most important prey item (86.9% IIR), followed by cephalopods (12.3% IIR). Other preys were in low frequency (<1% IIR) and they were represented by elasmobranch fishes, marine birds and marine mammals. No differences in diet were found between sexes of shortfin mako, however, it was detected variation between seasons and fishing zones. According to its diet the mako shark is considered a generalist species.
