Christian Klug | University of Zurich, Switzerland (original) (raw)
Papers by Christian Klug
Swiss Journal of Palaeontology
Soft-tissue preservation in molluscs is generally rare, particularly in bivalves and gastropods. ... more Soft-tissue preservation in molluscs is generally rare, particularly in bivalves and gastropods. Here, we report a three-dimensionally preserved specimen of the limid Acesta clypeiformis from the Cenomanian of France that shows preservation of organic structures of the adductor muscles. Examination under UV-light revealed likely phosphatisation of organic remains, which was corroborated by EDX-analyses. We suggest that the parts of the adductor muscles that are very close to the attachment are particularly resistant to decay and thus may be preserved even under taphonomic conditions usually not favouring soft-tissue fossilisation.
Swiss Journal of Palaeontology
The impact of increasing atmospheric CO2 and the resulting decreasing pH of seawater are in the f... more The impact of increasing atmospheric CO2 and the resulting decreasing pH of seawater are in the focus of current environmental research. These factors cause problems for marine calcifiers such as reduced calcification rates and the dissolution of calcareous skeletons. While the impact on recent organisms is well established, little is known about long-term evolutionary consequences. Here, we assessed whether ammonoids reacted to environmental change by changing septal thickness. We measured the septal thickness of ammonoid phragmocones through ontogeny in order to test the hypothesis that atmospheric pCO2, seawater pH and other factors affected aragonite biomineralisation in ammonoids. Particularly, we studied septal thickness of ammonoids before and after the ocean acidification event in the latest Triassic until the Early Cretaceous. Early Jurassic ammonoid lineages had thinner septa relative to diameter than their Late Triassic relatives, which we tentatively interpret as consequ...
C.: Alpha diversity and palaeoecology of a Late Devonian Fossillagerstätte from Morocco and its e... more C.: Alpha diversity and palaeoecology of a Late Devonian Fossillagerstätte from Morocco and its exceptionally preserved fish fauna 4.5
Proceedings of the Royal Society B: Biological Sciences, 2019
Anatomical knowledge of early chondrichthyans and estimates of their phylogeny are improving, but... more Anatomical knowledge of early chondrichthyans and estimates of their phylogeny are improving, but many taxa are still known only from microremains. The nearly cosmopolitan and regionally abundant Devonian genus Phoebodus has long been known solely from isolated teeth and fin spines. Here, we report the first skeletal remains of Phoebodus from the Famennian (Late Devonian) of the Maïder region of Morocco, revealing an anguilliform body, specialized braincase, hyoid arch, elongate jaws and rostrum, complementing its characteristic dentition and ctenacanth fin spines preceding both dorsal fins. Several of these features corroborate a likely close relationship with the Carboniferous species Thrinacodus gracia , and phylogenetic analysis places both taxa securely as members of the elasmobranch stem lineage. Identified as such, phoebodont teeth provide a plausible marker for range extension of the elasmobranchs into the Middle Devonian, thus providing a new minimum date for the origin of ...
Communications Biology, 2019
Coleoidea (squids and octopuses) comprise all crown group cephalopods except the Nautilida. Coleo... more Coleoidea (squids and octopuses) comprise all crown group cephalopods except the Nautilida. Coleoids are characterized by internal shell (endocochleate), ink sac and arm hooks, while nautilids lack an ink sac, arm hooks, suckers, and have an external conch (ectocochleate). Differentiating between straight conical conchs (orthocones) of Palaeozoic Coleoidea and other ectocochleates is only possible when rostrum (shell covering the chambered phragmocone) and body chamber are preserved. Here, we provide information on how this internalization might have evolved. We reexamined one of the oldest coleoids, Gordoniconus beargulchensis from the Early Carboniferous of the Bear Gulch Fossil-Lagerstätte (Montana) by synchrotron, various lights and Reflectance Transformation Imaging (RTI). This revealed previously unappreciated anatomical details, on which we base evolutionary scenarios of how the internalization and other evolutionary steps in early coleoid evolution proceeded. We suggest that conch internalization happened rather suddenly including early growth stages while the ink sac evolved slightly later.
Scientific Reports, 2019
We describe four complete specimens of the early squid-like cephalopod Clarkeiteuthis conocauda f... more We describe four complete specimens of the early squid-like cephalopod Clarkeiteuthis conocauda from the Toarcian Posidonienschiefer (Jurassic) each preserved with the bony fish Leptolepis bronni in its arms. Based on the arrangement of prey and predator, we suggest that the cephalopods caught and killed the fishes while still in well-oxygenated waters and then descended into oxygen-depleted water layers (distraction sinking) where the cephalopod suffocated. This explains the exceptional preservation, for which the posidonienschiefer is famed. this association raises the question for the hunting behaviour of belemnoid Coleoidea. Using the proportions of soft and skeletal body parts of diplobelids and belemnitids, we estimated their body mass and buoyancy and determined the centres of mass and buoyancy. these two points were very close to each other in belemnitids, implying a low hydrodynamic stability (when ignoring the fins), while in diplobelids, the distance between those centres was greater. this suggests that diplobelids usually assumed an oblique to vertical orientation of the body axis while belemnitids could effortlessly achieve a horizontal orientation of their body. Presuming larger fins were attached to the bigger belemnitid rostra, belemnitids were better swimmers and perhaps pursuit predators while diplobelids rather ambushed their prey. Among Mesozoic coleoids (cephalopods with internal hard parts that include octopuses, squid, and cuttlefish), belemnoids represent the most abundant and best documented clade. In the Jurassic, it is mainly the Belemntitida that can regionally be found in rock-forming numbers, but remains of the Diplobelida also occur occasionally. Despite their abundance, direct evidence for the swimming and hunting behaviour of these extinct cephalopods is extremely rare 1-4. Here, we document four cases of Early Jurassic coleoids, which all hold a small bony fish in their arm crowns (Fig. 1, Suppl. Figs 2, 4). Such preservation requires exceptional taphonomic conditions, for which the Early Jurassic Posidonienschiefer is world-renowned 5-10. Repeated hypoxic to anoxic bottom water conditions 11,12 decelerated decay processes and allowed pyritization or phosphatization of soft tissues that are only rarely fossilized otherwise 13-16. These conditions persisted over a long time and in a rather vast area from southern France via northern Switzerland throughout much of Germany and into Great Britain; therefore, these widely distributed conditions allowed the formation of one of the most famous Konservatlagerstätten 8,17 , the Posidonienschiefer (= Posidonia Shale or 'Schistes cartons'). From this point of view, it is not surprising that the first rostrum-bearing belemnite preserved with soft-parts was found in the Posidonienschiefer 6,18,19. Some other cephalopods also show anatomical details of soft tissues that are usually not preserved (e.g., digestive tract in ammonites 6 ; musculature and gills in non-belemoid coleoids 20-22). Despite the extreme scarcity of cephalopods preserved with their prey, the specimen presented here was never described in detail and only figured once without detailed discussion 23. Recently, a second specimen documenting the same behaviour was published 10. In the Posidonienschiefer, molluscs represent the most common macrofossils; among those, bivalves are very abundant followed by ammonites and belemnites 5,6. Other molluscs such as non-belemnoid coleoids and nautilids are rarer and complete specimens preserved with intact arm crowns are very rare. The diplobelids described
Bulletin of Geosciences, 2017
During the Palaeozoic, a diversification in modes of life occurred that included a wide range of ... more During the Palaeozoic, a diversification in modes of life occurred that included a wide range of predators. Major macroecological events include the Cambrian Explosion (including the Agronomic Substrate Revolution and the here introduced 'Ediacaran-Cambrian Mouthpart Armament'), the Great Ordovician Biodiversification Event, the Palaeozoic Plankton Revolution, the Siluro-Devonian Jaw Armament (newly introduced herein) and the Devonian Nekton Revolution. Here, we discuss the evolutionary advancement in oral equipment, i.e. the Palaeozoic evolution of mouthparts and jaws in a macroecological context. It appears that particularly the latest Neoproterozoic to Cambrian and the Silurian to Devonian were phases when important innovations in the evolution of oral structures occurred.
Palaeontographica Abteilung A, 2008
Abstract Early Emsian claystones and marls of the Tafilalt yielded two diverse and prolific fauna... more Abstract Early Emsian claystones and marls of the Tafilalt yielded two diverse and prolific faunas with nearly 5000 specimens belonging to at least 100 species being recovered and identified. The older of the two faunas contains what may be the oldest bactritids, pyrgocystid edrioasteroids, phyllocarid carapaces, complete asteropygid trilobites, acanthodian fin spines rarely preserved as pairs, and articulated machaeridians. Additionally, the lower interval yielded a diverse and largely infaunal bivalve assemblage. The younger fauna is ...
Cretaceous Research, 2017
The Alpstein (cantons of Appenzell Ausserrhoden, Appenzell Innerrhoden and St. Gallen, northeaste... more The Alpstein (cantons of Appenzell Ausserrhoden, Appenzell Innerrhoden and St. Gallen, northeastern Switzerland) has been of great interest for geologists over the last decades because of its excellent outcrops. However, there was no comprehensive overview over its Cretaceous fossil content. Here, we describe the cephalopod associations, which are moderately to highly diverse in some strata of the Alpstein. Furthermore, we document the regional palaeoecological changes that occurred during the radiation of heteromorph ammonites (ancyloceratids, scaphitids, turrilitids). To examine the palaeoecological changes,
PeerJ, 2015
Nautilusremains of great interest to palaeontologists after a long history of actualistic compari... more Nautilusremains of great interest to palaeontologists after a long history of actualistic comparisons and speculations on aspects of the palaeoecology of fossil cephalopods, which are otherwise impossible to assess. Although a large amount of work has been dedicated toNautilusecology, conch geometry and volumes of shell parts and chambers have been studied less frequently. In addition, although the focus on volumetric analyses for ammonites has been increasing recently with the development of computed tomographic technology, the intraspecific variation of volumetric parameters has never been examined. To investigate the intraspecific variation of the phragmocone chamber volumes throughout ontogeny, 30 specimens of RecentNautilus pompiliusand two Middle Jurassic ammonites (Normannites mitis) were reconstructed using computed tomography and grinding tomography, respectively. Both of the ontogenetic growth trajectories from the twoNormannitesdemonstrate logistic increase. However, a co...
Swiss Journal of Palaeontology, 2015
Plesioteuthis is a coleoid rather well known from the classical Fossillagerstätten of southern Ge... more Plesioteuthis is a coleoid rather well known from the classical Fossillagerstätten of southern Germany (Solnhofen-Eichstätt region, Nusplingen). Here, we present two new specimens that display unusually preserved cirri-bearing arms and two pairs of fins. Based on these specimens, we shortly discuss in how far arm arrangement in the fossils might reflect behaviour. Additionally, we revise the phylogenetic position of the Jurassic vampyromorphs.
Since the Cambrian Explosion, giant marine invertebrate species have evolved iteratively in sever... more Since the Cambrian Explosion, giant marine invertebrate species have evolved iteratively in several groups. In the Palaeozoic, marine invertebrate gigantism was heterogeneously distributed through time and space; changes in maximum sizes show no clear relationship with atmospheric or oceanic oxygen and other environmental factors. Although gigantism has found an explanation for Carboniferous land invertebrates in the atmospheric oxygen peak, marine gigantism has not been studied empirically and explained comprehensively. By quantifying the spatiotemporal distribution of the largest representatives of some major marine invertebrate clades, we assessed links between ecological parameters and giant growth. These occurrence data suggest that temperature and latitude in combination with oxygen played important roles. Marine invertebrate gigantism developed in certain phases and regions with a greater number of extremely large species and their occurrences shifted independently from middle towards low latitudes during the Palaeozoic in all examined groups. This trend roughly coincides with the Late Devonian to Carboniferous cooling and regression as well as with a rise in atmospheric oxygen. This shows how global environmental changes can control the geographical distribution of organisms and that the optimal ecological requirements might differ depending on body size: extremely large organisms might react less flexibly to ecological changes.
Geologica Belgica
The first ammonoids from the Lower Emsian (Devonian) of Belgium are described. They belong to the... more The first ammonoids from the Lower Emsian (Devonian) of Belgium are described. They belong to the Anetoceratinae, which show the most plesiomorphic characters of all ammonoids. This is the second report of Early Emsian ammonoids within the Rhenish facies of the Rhenish Slate Mountains (Belgium, Germany), in this case from the Belgian part of the Eifel (Burg Reuland). It highlights the possible importance of ammonoids for the correlation of the Emsian in its traditional German sense and the Emsian in the global sense as delimited by the GSSPs. Newly collected, age-significant brachiopods of the genera Arduspirifer and Euryspirifer and other previously reported fossils indicate a middle or late Early Emsian (Singhofen or Vallendar) age (in German sense) for this locality. We extend the range of Ivoites schindewolfi outside of the Hunsrück Basin and further corroborate an age younger than Ulmen for parts of the Hunsrück Slate.
Topics in Geobiology, 2015
In order to put the origin of the Ammonoidea into the broader evolutionary context, we review the... more In order to put the origin of the Ammonoidea into the broader evolutionary context, we review the hypothesis on the origin of cephalopods in general, the origin of bactritids as well as the origin of bactritids with their respective Bauplan characters. We also list major morphological changes that occurred between the origin of cephalopods until the early evolution of ammonoids.
Topics in Geobiology, 2015
The Ammonoidea are well represented in terms of numbers of species over a large range of time and... more The Ammonoidea are well represented in terms of numbers of species over a large range of time and they have survived many extinction events. The time interval from the Early Devonian through to the Triassic has seen ammonoid groups evolve and become extinct. The evolutionary history of the Paleozoic ammonoids was punctuated by some extinction events with near extinction events and subsequent recoveries. A Principal Components Analysis (PCA) based on the conch width index (CWI), umbilical width index (UWI) and whorl expansion rate (WER) parameters from 4834 ammonoid species of Devonian to Triassic age produced an empirical morphospace this time interval. The morphospace of Paleozoic ammonoids shows some subtle changes between the periods, but generally, the occupied area is remarkably similar.
Topics in Geobiology, 2015
Allometric growth between different parts of the shell often hampers the identification of mollus... more Allometric growth between different parts of the shell often hampers the identification of mollusk shells, particularly in such cases where preadult shell growth varies strongly. Especially in gastropods, the terminal aperture is often less variable and yields morphological information essential for species determination (e.g. Vermeij 1993; Urdy et al. 2010a, b). In fossil mollusk shells, the adult aperture (peristome)is often missing, partially due to an early death, and partially due to destructive processes, which occurred post mortem (taphonomy). Therefore, the entire shell ontogeny is known only from a small fraction of all ammonoid taxa (e.g., Landman et al. 2012). Nevertheless, knowledge of the adult shell of ammonoids is very important since it can yield morphological information essential for systematics and for the reconstruction of various aspects of their paleobiology.
Swiss Journal of Palaeontology, 2013
On Aferdou El Mrakib, a large reef mound in the Maïder region (Anti-Atlas, Morocco), thick-shelle... more On Aferdou El Mrakib, a large reef mound in the Maïder region (Anti-Atlas, Morocco), thick-shelled gypidulids of two genera are locally very abundant. Like Stringocephalus in the shallow water limestone formations in Germany, these Moroccan brachiopods of the genera Devonogypa and Ivdelinia often display greenish shells. By analysing these shells by EDX, it turned out that the colour was possibly caused by impurities of Fe 2?-ions. The concentration varies, indicating that the colour is less dependent on the concentration than on shell thickness, because only the thickest parts of the shells appear green and thin-shelled forms never display the green colour. There is also some indication that the Fe content increases towards deeper shell layers (further away from the surface). In addition, we examined the quality and spatial distribution of sublethal injuries in over 200 specimens of Devonogypa and Ivdelinia. Shape, spatial distribution on the shells, and abundance of the sublethal injuries support the hypotheses that (1) the injuries had several causes, (2) some of these were inflicted by predators, probably cephalopods, and (3) many fractures and deformations might have been caused by the brachiopod shells hitting each other in dense populations in agitated water. The existence of dense clusters, built by the association of members of both genera or of only one taxon, is corroborated by the patchy occurrence of these brachiopods.
Palaeobiodiversity and Palaeoenvironments, 2014
Swiss Journal of Palaeontology
Soft-tissue preservation in molluscs is generally rare, particularly in bivalves and gastropods. ... more Soft-tissue preservation in molluscs is generally rare, particularly in bivalves and gastropods. Here, we report a three-dimensionally preserved specimen of the limid Acesta clypeiformis from the Cenomanian of France that shows preservation of organic structures of the adductor muscles. Examination under UV-light revealed likely phosphatisation of organic remains, which was corroborated by EDX-analyses. We suggest that the parts of the adductor muscles that are very close to the attachment are particularly resistant to decay and thus may be preserved even under taphonomic conditions usually not favouring soft-tissue fossilisation.
Swiss Journal of Palaeontology
The impact of increasing atmospheric CO2 and the resulting decreasing pH of seawater are in the f... more The impact of increasing atmospheric CO2 and the resulting decreasing pH of seawater are in the focus of current environmental research. These factors cause problems for marine calcifiers such as reduced calcification rates and the dissolution of calcareous skeletons. While the impact on recent organisms is well established, little is known about long-term evolutionary consequences. Here, we assessed whether ammonoids reacted to environmental change by changing septal thickness. We measured the septal thickness of ammonoid phragmocones through ontogeny in order to test the hypothesis that atmospheric pCO2, seawater pH and other factors affected aragonite biomineralisation in ammonoids. Particularly, we studied septal thickness of ammonoids before and after the ocean acidification event in the latest Triassic until the Early Cretaceous. Early Jurassic ammonoid lineages had thinner septa relative to diameter than their Late Triassic relatives, which we tentatively interpret as consequ...
C.: Alpha diversity and palaeoecology of a Late Devonian Fossillagerstätte from Morocco and its e... more C.: Alpha diversity and palaeoecology of a Late Devonian Fossillagerstätte from Morocco and its exceptionally preserved fish fauna 4.5
Proceedings of the Royal Society B: Biological Sciences, 2019
Anatomical knowledge of early chondrichthyans and estimates of their phylogeny are improving, but... more Anatomical knowledge of early chondrichthyans and estimates of their phylogeny are improving, but many taxa are still known only from microremains. The nearly cosmopolitan and regionally abundant Devonian genus Phoebodus has long been known solely from isolated teeth and fin spines. Here, we report the first skeletal remains of Phoebodus from the Famennian (Late Devonian) of the Maïder region of Morocco, revealing an anguilliform body, specialized braincase, hyoid arch, elongate jaws and rostrum, complementing its characteristic dentition and ctenacanth fin spines preceding both dorsal fins. Several of these features corroborate a likely close relationship with the Carboniferous species Thrinacodus gracia , and phylogenetic analysis places both taxa securely as members of the elasmobranch stem lineage. Identified as such, phoebodont teeth provide a plausible marker for range extension of the elasmobranchs into the Middle Devonian, thus providing a new minimum date for the origin of ...
Communications Biology, 2019
Coleoidea (squids and octopuses) comprise all crown group cephalopods except the Nautilida. Coleo... more Coleoidea (squids and octopuses) comprise all crown group cephalopods except the Nautilida. Coleoids are characterized by internal shell (endocochleate), ink sac and arm hooks, while nautilids lack an ink sac, arm hooks, suckers, and have an external conch (ectocochleate). Differentiating between straight conical conchs (orthocones) of Palaeozoic Coleoidea and other ectocochleates is only possible when rostrum (shell covering the chambered phragmocone) and body chamber are preserved. Here, we provide information on how this internalization might have evolved. We reexamined one of the oldest coleoids, Gordoniconus beargulchensis from the Early Carboniferous of the Bear Gulch Fossil-Lagerstätte (Montana) by synchrotron, various lights and Reflectance Transformation Imaging (RTI). This revealed previously unappreciated anatomical details, on which we base evolutionary scenarios of how the internalization and other evolutionary steps in early coleoid evolution proceeded. We suggest that conch internalization happened rather suddenly including early growth stages while the ink sac evolved slightly later.
Scientific Reports, 2019
We describe four complete specimens of the early squid-like cephalopod Clarkeiteuthis conocauda f... more We describe four complete specimens of the early squid-like cephalopod Clarkeiteuthis conocauda from the Toarcian Posidonienschiefer (Jurassic) each preserved with the bony fish Leptolepis bronni in its arms. Based on the arrangement of prey and predator, we suggest that the cephalopods caught and killed the fishes while still in well-oxygenated waters and then descended into oxygen-depleted water layers (distraction sinking) where the cephalopod suffocated. This explains the exceptional preservation, for which the posidonienschiefer is famed. this association raises the question for the hunting behaviour of belemnoid Coleoidea. Using the proportions of soft and skeletal body parts of diplobelids and belemnitids, we estimated their body mass and buoyancy and determined the centres of mass and buoyancy. these two points were very close to each other in belemnitids, implying a low hydrodynamic stability (when ignoring the fins), while in diplobelids, the distance between those centres was greater. this suggests that diplobelids usually assumed an oblique to vertical orientation of the body axis while belemnitids could effortlessly achieve a horizontal orientation of their body. Presuming larger fins were attached to the bigger belemnitid rostra, belemnitids were better swimmers and perhaps pursuit predators while diplobelids rather ambushed their prey. Among Mesozoic coleoids (cephalopods with internal hard parts that include octopuses, squid, and cuttlefish), belemnoids represent the most abundant and best documented clade. In the Jurassic, it is mainly the Belemntitida that can regionally be found in rock-forming numbers, but remains of the Diplobelida also occur occasionally. Despite their abundance, direct evidence for the swimming and hunting behaviour of these extinct cephalopods is extremely rare 1-4. Here, we document four cases of Early Jurassic coleoids, which all hold a small bony fish in their arm crowns (Fig. 1, Suppl. Figs 2, 4). Such preservation requires exceptional taphonomic conditions, for which the Early Jurassic Posidonienschiefer is world-renowned 5-10. Repeated hypoxic to anoxic bottom water conditions 11,12 decelerated decay processes and allowed pyritization or phosphatization of soft tissues that are only rarely fossilized otherwise 13-16. These conditions persisted over a long time and in a rather vast area from southern France via northern Switzerland throughout much of Germany and into Great Britain; therefore, these widely distributed conditions allowed the formation of one of the most famous Konservatlagerstätten 8,17 , the Posidonienschiefer (= Posidonia Shale or 'Schistes cartons'). From this point of view, it is not surprising that the first rostrum-bearing belemnite preserved with soft-parts was found in the Posidonienschiefer 6,18,19. Some other cephalopods also show anatomical details of soft tissues that are usually not preserved (e.g., digestive tract in ammonites 6 ; musculature and gills in non-belemoid coleoids 20-22). Despite the extreme scarcity of cephalopods preserved with their prey, the specimen presented here was never described in detail and only figured once without detailed discussion 23. Recently, a second specimen documenting the same behaviour was published 10. In the Posidonienschiefer, molluscs represent the most common macrofossils; among those, bivalves are very abundant followed by ammonites and belemnites 5,6. Other molluscs such as non-belemnoid coleoids and nautilids are rarer and complete specimens preserved with intact arm crowns are very rare. The diplobelids described
Bulletin of Geosciences, 2017
During the Palaeozoic, a diversification in modes of life occurred that included a wide range of ... more During the Palaeozoic, a diversification in modes of life occurred that included a wide range of predators. Major macroecological events include the Cambrian Explosion (including the Agronomic Substrate Revolution and the here introduced 'Ediacaran-Cambrian Mouthpart Armament'), the Great Ordovician Biodiversification Event, the Palaeozoic Plankton Revolution, the Siluro-Devonian Jaw Armament (newly introduced herein) and the Devonian Nekton Revolution. Here, we discuss the evolutionary advancement in oral equipment, i.e. the Palaeozoic evolution of mouthparts and jaws in a macroecological context. It appears that particularly the latest Neoproterozoic to Cambrian and the Silurian to Devonian were phases when important innovations in the evolution of oral structures occurred.
Palaeontographica Abteilung A, 2008
Abstract Early Emsian claystones and marls of the Tafilalt yielded two diverse and prolific fauna... more Abstract Early Emsian claystones and marls of the Tafilalt yielded two diverse and prolific faunas with nearly 5000 specimens belonging to at least 100 species being recovered and identified. The older of the two faunas contains what may be the oldest bactritids, pyrgocystid edrioasteroids, phyllocarid carapaces, complete asteropygid trilobites, acanthodian fin spines rarely preserved as pairs, and articulated machaeridians. Additionally, the lower interval yielded a diverse and largely infaunal bivalve assemblage. The younger fauna is ...
Cretaceous Research, 2017
The Alpstein (cantons of Appenzell Ausserrhoden, Appenzell Innerrhoden and St. Gallen, northeaste... more The Alpstein (cantons of Appenzell Ausserrhoden, Appenzell Innerrhoden and St. Gallen, northeastern Switzerland) has been of great interest for geologists over the last decades because of its excellent outcrops. However, there was no comprehensive overview over its Cretaceous fossil content. Here, we describe the cephalopod associations, which are moderately to highly diverse in some strata of the Alpstein. Furthermore, we document the regional palaeoecological changes that occurred during the radiation of heteromorph ammonites (ancyloceratids, scaphitids, turrilitids). To examine the palaeoecological changes,
PeerJ, 2015
Nautilusremains of great interest to palaeontologists after a long history of actualistic compari... more Nautilusremains of great interest to palaeontologists after a long history of actualistic comparisons and speculations on aspects of the palaeoecology of fossil cephalopods, which are otherwise impossible to assess. Although a large amount of work has been dedicated toNautilusecology, conch geometry and volumes of shell parts and chambers have been studied less frequently. In addition, although the focus on volumetric analyses for ammonites has been increasing recently with the development of computed tomographic technology, the intraspecific variation of volumetric parameters has never been examined. To investigate the intraspecific variation of the phragmocone chamber volumes throughout ontogeny, 30 specimens of RecentNautilus pompiliusand two Middle Jurassic ammonites (Normannites mitis) were reconstructed using computed tomography and grinding tomography, respectively. Both of the ontogenetic growth trajectories from the twoNormannitesdemonstrate logistic increase. However, a co...
Swiss Journal of Palaeontology, 2015
Plesioteuthis is a coleoid rather well known from the classical Fossillagerstätten of southern Ge... more Plesioteuthis is a coleoid rather well known from the classical Fossillagerstätten of southern Germany (Solnhofen-Eichstätt region, Nusplingen). Here, we present two new specimens that display unusually preserved cirri-bearing arms and two pairs of fins. Based on these specimens, we shortly discuss in how far arm arrangement in the fossils might reflect behaviour. Additionally, we revise the phylogenetic position of the Jurassic vampyromorphs.
Since the Cambrian Explosion, giant marine invertebrate species have evolved iteratively in sever... more Since the Cambrian Explosion, giant marine invertebrate species have evolved iteratively in several groups. In the Palaeozoic, marine invertebrate gigantism was heterogeneously distributed through time and space; changes in maximum sizes show no clear relationship with atmospheric or oceanic oxygen and other environmental factors. Although gigantism has found an explanation for Carboniferous land invertebrates in the atmospheric oxygen peak, marine gigantism has not been studied empirically and explained comprehensively. By quantifying the spatiotemporal distribution of the largest representatives of some major marine invertebrate clades, we assessed links between ecological parameters and giant growth. These occurrence data suggest that temperature and latitude in combination with oxygen played important roles. Marine invertebrate gigantism developed in certain phases and regions with a greater number of extremely large species and their occurrences shifted independently from middle towards low latitudes during the Palaeozoic in all examined groups. This trend roughly coincides with the Late Devonian to Carboniferous cooling and regression as well as with a rise in atmospheric oxygen. This shows how global environmental changes can control the geographical distribution of organisms and that the optimal ecological requirements might differ depending on body size: extremely large organisms might react less flexibly to ecological changes.
Geologica Belgica
The first ammonoids from the Lower Emsian (Devonian) of Belgium are described. They belong to the... more The first ammonoids from the Lower Emsian (Devonian) of Belgium are described. They belong to the Anetoceratinae, which show the most plesiomorphic characters of all ammonoids. This is the second report of Early Emsian ammonoids within the Rhenish facies of the Rhenish Slate Mountains (Belgium, Germany), in this case from the Belgian part of the Eifel (Burg Reuland). It highlights the possible importance of ammonoids for the correlation of the Emsian in its traditional German sense and the Emsian in the global sense as delimited by the GSSPs. Newly collected, age-significant brachiopods of the genera Arduspirifer and Euryspirifer and other previously reported fossils indicate a middle or late Early Emsian (Singhofen or Vallendar) age (in German sense) for this locality. We extend the range of Ivoites schindewolfi outside of the Hunsrück Basin and further corroborate an age younger than Ulmen for parts of the Hunsrück Slate.
Topics in Geobiology, 2015
In order to put the origin of the Ammonoidea into the broader evolutionary context, we review the... more In order to put the origin of the Ammonoidea into the broader evolutionary context, we review the hypothesis on the origin of cephalopods in general, the origin of bactritids as well as the origin of bactritids with their respective Bauplan characters. We also list major morphological changes that occurred between the origin of cephalopods until the early evolution of ammonoids.
Topics in Geobiology, 2015
The Ammonoidea are well represented in terms of numbers of species over a large range of time and... more The Ammonoidea are well represented in terms of numbers of species over a large range of time and they have survived many extinction events. The time interval from the Early Devonian through to the Triassic has seen ammonoid groups evolve and become extinct. The evolutionary history of the Paleozoic ammonoids was punctuated by some extinction events with near extinction events and subsequent recoveries. A Principal Components Analysis (PCA) based on the conch width index (CWI), umbilical width index (UWI) and whorl expansion rate (WER) parameters from 4834 ammonoid species of Devonian to Triassic age produced an empirical morphospace this time interval. The morphospace of Paleozoic ammonoids shows some subtle changes between the periods, but generally, the occupied area is remarkably similar.
Topics in Geobiology, 2015
Allometric growth between different parts of the shell often hampers the identification of mollus... more Allometric growth between different parts of the shell often hampers the identification of mollusk shells, particularly in such cases where preadult shell growth varies strongly. Especially in gastropods, the terminal aperture is often less variable and yields morphological information essential for species determination (e.g. Vermeij 1993; Urdy et al. 2010a, b). In fossil mollusk shells, the adult aperture (peristome)is often missing, partially due to an early death, and partially due to destructive processes, which occurred post mortem (taphonomy). Therefore, the entire shell ontogeny is known only from a small fraction of all ammonoid taxa (e.g., Landman et al. 2012). Nevertheless, knowledge of the adult shell of ammonoids is very important since it can yield morphological information essential for systematics and for the reconstruction of various aspects of their paleobiology.
Swiss Journal of Palaeontology, 2013
On Aferdou El Mrakib, a large reef mound in the Maïder region (Anti-Atlas, Morocco), thick-shelle... more On Aferdou El Mrakib, a large reef mound in the Maïder region (Anti-Atlas, Morocco), thick-shelled gypidulids of two genera are locally very abundant. Like Stringocephalus in the shallow water limestone formations in Germany, these Moroccan brachiopods of the genera Devonogypa and Ivdelinia often display greenish shells. By analysing these shells by EDX, it turned out that the colour was possibly caused by impurities of Fe 2?-ions. The concentration varies, indicating that the colour is less dependent on the concentration than on shell thickness, because only the thickest parts of the shells appear green and thin-shelled forms never display the green colour. There is also some indication that the Fe content increases towards deeper shell layers (further away from the surface). In addition, we examined the quality and spatial distribution of sublethal injuries in over 200 specimens of Devonogypa and Ivdelinia. Shape, spatial distribution on the shells, and abundance of the sublethal injuries support the hypotheses that (1) the injuries had several causes, (2) some of these were inflicted by predators, probably cephalopods, and (3) many fractures and deformations might have been caused by the brachiopod shells hitting each other in dense populations in agitated water. The existence of dense clusters, built by the association of members of both genera or of only one taxon, is corroborated by the patchy occurrence of these brachiopods.
Palaeobiodiversity and Palaeoenvironments, 2014