Helmut Keupp - Academia.edu (original) (raw)
Papers by Helmut Keupp
… and Past: New Insights and Fresh …, Jan 1, 2007
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 2013
For Phragmoteuthis conocauda (Quenstedt, 1849) from the Lower Toarcian Posidonia Shale (South Ger... more For Phragmoteuthis conocauda (Quenstedt, 1849) from the Lower Toarcian Posidonia Shale (South Germany) and Phragmoteuthis montefiorei (Buckman, 1880) from the Upper Sinemurian Charmouth Mudstone Formation (Dorset, UK), a new belemnoid genus, Clarkeiteuthis, is introduced. Clarkeiteuthis significantly differs from Phragmoteuthis by the absence of a three-lobed proostracum as well as the possession of a unique hook shape. Owing to the presence of a proostracum, which is significantly narrower than in belemnotheutids, Clarkeiteuthis is accommodated within the Diplobelida. This taxonomic revision has an influence on our previous knowledge about the Phragmoteuthida. The taxon already disappeared after the Sinemurian (instead of Toarcian). Hence, the youngest known representative of the Phragmoteuthida is Phragmoteuthis huxleyi dono- van, 2006. The true number of arms, which was originally based on the ten arms of Clarkeiteuthis conocauda, is still unknown in phragmoteuthid belemnoids. The new assignment of Clarkeiteuthis conocauda and Clarkeiteuthis montefiorei induces the presence of hooklets (onychites) within the Diplobelida, which was previously questioned.
Palaeontology, 2012
Groenlandibelus rosenkrantzi from the Maastrichtian of Greenland has long been thought to constit... more Groenlandibelus rosenkrantzi from the Maastrichtian of Greenland has long been thought to constitute an early representative of spirulid coleoids. This study shows that this view must be reassessed, at least in part. A re-investigation of the types and of material recorded subsequently has revealed that none of these specimens is conspecific with the holotype of G. rosenkrantzi. Cyrtobelus birkelundae gen. nov, sp. nov. differs from the type of G. rosenkrantzi in having lower chambers and in lacking an apically elongated sheath. The longiconic phragmocone of G. rosenkrantzi has more features in common with the presumed spirulid genus Naefia. A specimen described in detail by J. A. Jeletzky in the mid 1960s as 'G. rosenkrantzi' is designated holotype of C. birkelundae sp. nov., which means that internal phragmocone features are still unknown in G. rosenkrantzi. Cyrtobelus hornbyense gen. nov, sp. nov. from the Campanian of western Canada constitutes the first record of early spirulids from the northeast Pacific, being based on seventeen extraordinarily well-preserved phragmocones. This species differs from C. birkelundae sp. nov. only in the width of the siphuncular tube. The presence of a caecum, a nacre-less conotheca that represents the continuation of the protoconch conotheca, conothecal flaps that anchor the mural parts of the septa, and a thin investmentlike sheath are characters shared only with Recent Spirula. In particular, the unusual protoconch architecture of Cyrtobelus gen. nov. challenges a phylogenetic origin within bactritoid-like coleoids.
Paläontologische Zeitschrift, 2013
The higher rank systematics of coleoid cephalopods are primarily based on the total number of arm... more The higher rank systematics of coleoid cephalopods are primarily based on the total number of arms. Completely preserved arm crows are, therefore, the most important character complex by which fossil representatives can be assigned to higher taxa. Whereas belemnoids-similar to modern Decabrachia-are well-known to have ten hooklet-bearing arms, recent studies have shown that Middle-Late Jurassic and Late Cretaceous gladiusbearing coleoids belong to the Vamyropoda, owing to having only eight hooklet-free arms. The arm number of Early Jurassic gladius-bearing coleoids was unclear for a long time. This paper, however, reports the first unequivocally complete arm crown from the Early Jurassic (Toarcian). It consists of eight strongly phosphatised arms of equal shape. Affinity with decabrachiate coleoids is therefore unlikely. The mantle sack of the specimen, which was identified as Loligosepia aalensis (Schübler in Zieten, 1832), has, furthermore, an unusual arrangement of numerous angular pieces. The irregular scattering of the mantle fragments was most probably caused by a scavenger. Finally, hooklets in the food residues in the posterior mantle indicate that Loligosepia preyed upon belemnites.
Palaeontology, 2013
The phylogenetic origin and the timing of origination of the Decabrachia are controversial. This ... more The phylogenetic origin and the timing of origination of the Decabrachia are controversial. This is due to a poor understanding of character complexes relating to the shell, which causes difficulties in establishing homologies among different taxa. One central problem concerns a clear differentiation between belemnoids and early spirulids.
Cretaceous Research, 2012
The phylogenetic origin of the Sepiida is still unclear. The presumed derivation from diplobelid ... more The phylogenetic origin of the Sepiida is still unclear. The presumed derivation from diplobelid belemnoids can be tested by comparison of their initial chambers (protoconchs). The first investigation of a juvenile phragmocone of the diplobelid Conoteuthis hayakawai from the Cenomanian of Hokkaido (northern Japan) yielded surprising insights into the internal protoconch morphology of the Diplobelida. The Conoteuthis protoconch exhibits in many aspects a mosaic of the belemnitid and the spirulid protoconch types. Whereas the sepiid protoconch represents most probably a modification of the spirulid type, the Conoteuthis protoconch is unique in having a closed (imperforated) proseptum. Apart from this, Conoteuthis differs in many other characters from the earliest sepiids (Ceratisepia, Belosepia), which makes a closer relationship unlikely.
Neues Jahrbuch f&# 252; r …, Jan 1, 2007
were previously the only two species of plesioteuthidid coleoids luiown from the Solnhofe n Platt... more were previously the only two species of plesioteuthidid coleoids luiown from the Solnhofe n Plattenkalks . Based on morphological comparisons of 154 specimens from the Solnhofen area, a thir d taxon must be considered as valid: Plesioteuthis subovata (MONSTER, 1846) . Additionally, it turne d out that "Senefelderiteuthis Icaussi" is identical with Dorateuthis tricarinata (MONSTER, 1846) . The stratigraphical range of the genus Dorateuthis can now be extended from the Late Cretaceou s to the Late Jurassic . Despite a remarkable similarity between prototeuthid and teuthid gladii, Prototeuthidids are attributed to the Vampyropoda . Unambiguous characters of teuthid Decabrachia such as a ventrolateral pair of elongated tentacles are unknown from the fossil record . Instead, characters such as interbrachial web, radial suckers and cirri rather indicate a closer relationship with th e Vampyropoda .
A new demospongid genus and species is described from the Upper Jurassic (Lower Tithonian) Platte... more A new demospongid genus and species is described from the Upper Jurassic (Lower Tithonian) Plattenkalk of Langenaltheim near Solnhofen/Bavaria. Both the morphology and the spiculation of the new taxon Neochoiaella frattigianii n. gen. n. sp.
A newly found adult specimen of the aptychophoran ammonite microconch Ebrayiceras from the Lower ... more A newly found adult specimen of the aptychophoran ammonite microconch Ebrayiceras from the Lower Bathonian of Sengenthal, Oberpfalz (Germany, Bavaria) exhibits completely preserved prominent peristomal apophyses. The specimen is described and figured in some detail in order to demonstrate the extreme constriction of the aperture by the apophyses. These peristomal lappets are interpreted to represent a kind of protection shield, particularly against intersexual cannibalism during mating when the ammonite had to expose soft parts. It can be assumed that the adult Ebrayiceras was able to protrude only small brachia and hyponome through the minute apertural openings which raises the question how the animal could gather sufficient food. We suggest the possibility of mucous web feeding in Ebrayiceras as is e. g. the case in modern holoplanktic and planktotrophic thecosome gastropods. Such a feeding strategy would allow the ammonite to capture fair amounts of small planktic prey using relatively short brachia and without the necessity of protruding its head. It must be concluded that only because of such or a similar feeding strategy the extreme peristomal constriction of Ebrayiceras was possible. It is speculated that other aptychophoran ammonites also used a mucous web to capture planktic prey.
Engeser, T., and Keupp, H. 2007. Gladius shape variation in coleoid cephalopod Trachyteuthis from... more Engeser, T., and Keupp, H. 2007. Gladius shape variation in coleoid cephalopod Trachyteuthis from the Upper Jurassic Nusplingen and Solnhofen Plattenkalks. Acta Palaeontologica Polonica 52 (3): 575-589.
For more than a decade, Magnetic Resonance Imaging (MRI) has been routinely employed in clinical ... more For more than a decade, Magnetic Resonance Imaging (MRI) has been routinely employed in clinical diagnostics because it allows non-invasive studies of anatomical structures and physiological processes in vivo and to differentiate between healthy and pathological states, particularly of soft tissue. Here, we demonstrate that MRI can likewise be applied to fossilized biological samples and help in elucidating paleopathological and paleoecological questions: Five anomalous guards of Jurassic and Cretaceous belemnites are presented along with putative paleopathological diagnoses directly derived from 3D MR images with microscopic resolution. Syn vivo deformities of both the mineralized internal rostrum and the surrounding former soft tissue can be traced back in part to traumatic events of predator-prey-interactions, and partly to parasitism. Besides, evidence is presented that the frequently observed anomalous apical collar might be indicative of an inflammatory disease. These findings highlight the potential of Magnetic Resonance techniques for further paleontological applications.
… and Past: New Insights and Fresh …, Jan 1, 2007
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 2013
For Phragmoteuthis conocauda (Quenstedt, 1849) from the Lower Toarcian Posidonia Shale (South Ger... more For Phragmoteuthis conocauda (Quenstedt, 1849) from the Lower Toarcian Posidonia Shale (South Germany) and Phragmoteuthis montefiorei (Buckman, 1880) from the Upper Sinemurian Charmouth Mudstone Formation (Dorset, UK), a new belemnoid genus, Clarkeiteuthis, is introduced. Clarkeiteuthis significantly differs from Phragmoteuthis by the absence of a three-lobed proostracum as well as the possession of a unique hook shape. Owing to the presence of a proostracum, which is significantly narrower than in belemnotheutids, Clarkeiteuthis is accommodated within the Diplobelida. This taxonomic revision has an influence on our previous knowledge about the Phragmoteuthida. The taxon already disappeared after the Sinemurian (instead of Toarcian). Hence, the youngest known representative of the Phragmoteuthida is Phragmoteuthis huxleyi dono- van, 2006. The true number of arms, which was originally based on the ten arms of Clarkeiteuthis conocauda, is still unknown in phragmoteuthid belemnoids. The new assignment of Clarkeiteuthis conocauda and Clarkeiteuthis montefiorei induces the presence of hooklets (onychites) within the Diplobelida, which was previously questioned.
Palaeontology, 2012
Groenlandibelus rosenkrantzi from the Maastrichtian of Greenland has long been thought to constit... more Groenlandibelus rosenkrantzi from the Maastrichtian of Greenland has long been thought to constitute an early representative of spirulid coleoids. This study shows that this view must be reassessed, at least in part. A re-investigation of the types and of material recorded subsequently has revealed that none of these specimens is conspecific with the holotype of G. rosenkrantzi. Cyrtobelus birkelundae gen. nov, sp. nov. differs from the type of G. rosenkrantzi in having lower chambers and in lacking an apically elongated sheath. The longiconic phragmocone of G. rosenkrantzi has more features in common with the presumed spirulid genus Naefia. A specimen described in detail by J. A. Jeletzky in the mid 1960s as 'G. rosenkrantzi' is designated holotype of C. birkelundae sp. nov., which means that internal phragmocone features are still unknown in G. rosenkrantzi. Cyrtobelus hornbyense gen. nov, sp. nov. from the Campanian of western Canada constitutes the first record of early spirulids from the northeast Pacific, being based on seventeen extraordinarily well-preserved phragmocones. This species differs from C. birkelundae sp. nov. only in the width of the siphuncular tube. The presence of a caecum, a nacre-less conotheca that represents the continuation of the protoconch conotheca, conothecal flaps that anchor the mural parts of the septa, and a thin investmentlike sheath are characters shared only with Recent Spirula. In particular, the unusual protoconch architecture of Cyrtobelus gen. nov. challenges a phylogenetic origin within bactritoid-like coleoids.
Paläontologische Zeitschrift, 2013
The higher rank systematics of coleoid cephalopods are primarily based on the total number of arm... more The higher rank systematics of coleoid cephalopods are primarily based on the total number of arms. Completely preserved arm crows are, therefore, the most important character complex by which fossil representatives can be assigned to higher taxa. Whereas belemnoids-similar to modern Decabrachia-are well-known to have ten hooklet-bearing arms, recent studies have shown that Middle-Late Jurassic and Late Cretaceous gladiusbearing coleoids belong to the Vamyropoda, owing to having only eight hooklet-free arms. The arm number of Early Jurassic gladius-bearing coleoids was unclear for a long time. This paper, however, reports the first unequivocally complete arm crown from the Early Jurassic (Toarcian). It consists of eight strongly phosphatised arms of equal shape. Affinity with decabrachiate coleoids is therefore unlikely. The mantle sack of the specimen, which was identified as Loligosepia aalensis (Schübler in Zieten, 1832), has, furthermore, an unusual arrangement of numerous angular pieces. The irregular scattering of the mantle fragments was most probably caused by a scavenger. Finally, hooklets in the food residues in the posterior mantle indicate that Loligosepia preyed upon belemnites.
Palaeontology, 2013
The phylogenetic origin and the timing of origination of the Decabrachia are controversial. This ... more The phylogenetic origin and the timing of origination of the Decabrachia are controversial. This is due to a poor understanding of character complexes relating to the shell, which causes difficulties in establishing homologies among different taxa. One central problem concerns a clear differentiation between belemnoids and early spirulids.
Cretaceous Research, 2012
The phylogenetic origin of the Sepiida is still unclear. The presumed derivation from diplobelid ... more The phylogenetic origin of the Sepiida is still unclear. The presumed derivation from diplobelid belemnoids can be tested by comparison of their initial chambers (protoconchs). The first investigation of a juvenile phragmocone of the diplobelid Conoteuthis hayakawai from the Cenomanian of Hokkaido (northern Japan) yielded surprising insights into the internal protoconch morphology of the Diplobelida. The Conoteuthis protoconch exhibits in many aspects a mosaic of the belemnitid and the spirulid protoconch types. Whereas the sepiid protoconch represents most probably a modification of the spirulid type, the Conoteuthis protoconch is unique in having a closed (imperforated) proseptum. Apart from this, Conoteuthis differs in many other characters from the earliest sepiids (Ceratisepia, Belosepia), which makes a closer relationship unlikely.
Neues Jahrbuch f&# 252; r …, Jan 1, 2007
were previously the only two species of plesioteuthidid coleoids luiown from the Solnhofe n Platt... more were previously the only two species of plesioteuthidid coleoids luiown from the Solnhofe n Plattenkalks . Based on morphological comparisons of 154 specimens from the Solnhofen area, a thir d taxon must be considered as valid: Plesioteuthis subovata (MONSTER, 1846) . Additionally, it turne d out that "Senefelderiteuthis Icaussi" is identical with Dorateuthis tricarinata (MONSTER, 1846) . The stratigraphical range of the genus Dorateuthis can now be extended from the Late Cretaceou s to the Late Jurassic . Despite a remarkable similarity between prototeuthid and teuthid gladii, Prototeuthidids are attributed to the Vampyropoda . Unambiguous characters of teuthid Decabrachia such as a ventrolateral pair of elongated tentacles are unknown from the fossil record . Instead, characters such as interbrachial web, radial suckers and cirri rather indicate a closer relationship with th e Vampyropoda .
A new demospongid genus and species is described from the Upper Jurassic (Lower Tithonian) Platte... more A new demospongid genus and species is described from the Upper Jurassic (Lower Tithonian) Plattenkalk of Langenaltheim near Solnhofen/Bavaria. Both the morphology and the spiculation of the new taxon Neochoiaella frattigianii n. gen. n. sp.
A newly found adult specimen of the aptychophoran ammonite microconch Ebrayiceras from the Lower ... more A newly found adult specimen of the aptychophoran ammonite microconch Ebrayiceras from the Lower Bathonian of Sengenthal, Oberpfalz (Germany, Bavaria) exhibits completely preserved prominent peristomal apophyses. The specimen is described and figured in some detail in order to demonstrate the extreme constriction of the aperture by the apophyses. These peristomal lappets are interpreted to represent a kind of protection shield, particularly against intersexual cannibalism during mating when the ammonite had to expose soft parts. It can be assumed that the adult Ebrayiceras was able to protrude only small brachia and hyponome through the minute apertural openings which raises the question how the animal could gather sufficient food. We suggest the possibility of mucous web feeding in Ebrayiceras as is e. g. the case in modern holoplanktic and planktotrophic thecosome gastropods. Such a feeding strategy would allow the ammonite to capture fair amounts of small planktic prey using relatively short brachia and without the necessity of protruding its head. It must be concluded that only because of such or a similar feeding strategy the extreme peristomal constriction of Ebrayiceras was possible. It is speculated that other aptychophoran ammonites also used a mucous web to capture planktic prey.
Engeser, T., and Keupp, H. 2007. Gladius shape variation in coleoid cephalopod Trachyteuthis from... more Engeser, T., and Keupp, H. 2007. Gladius shape variation in coleoid cephalopod Trachyteuthis from the Upper Jurassic Nusplingen and Solnhofen Plattenkalks. Acta Palaeontologica Polonica 52 (3): 575-589.
For more than a decade, Magnetic Resonance Imaging (MRI) has been routinely employed in clinical ... more For more than a decade, Magnetic Resonance Imaging (MRI) has been routinely employed in clinical diagnostics because it allows non-invasive studies of anatomical structures and physiological processes in vivo and to differentiate between healthy and pathological states, particularly of soft tissue. Here, we demonstrate that MRI can likewise be applied to fossilized biological samples and help in elucidating paleopathological and paleoecological questions: Five anomalous guards of Jurassic and Cretaceous belemnites are presented along with putative paleopathological diagnoses directly derived from 3D MR images with microscopic resolution. Syn vivo deformities of both the mineralized internal rostrum and the surrounding former soft tissue can be traced back in part to traumatic events of predator-prey-interactions, and partly to parasitism. Besides, evidence is presented that the frequently observed anomalous apical collar might be indicative of an inflammatory disease. These findings highlight the potential of Magnetic Resonance techniques for further paleontological applications.