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Jorge Esteve

University of West Bohemia, Centre of Biology, Earth and Environmental Sciences, Research Associate

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Smithsonian Institution

Universitat de València

Eduardo Mayoral

Huelva University

Eduardo Mayoral Alfaro

University of Kansas

Daniel Vizcaïno

Frederick A Sundberg

Natural History Museum, London

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Papers by Jorge Esteve

Intraspecific variability in paradoxidid trilobites from the Purujosa trilobite

Acta Palaeontologica Polonica, 2013

Eccaparadoxides? pradoanus and Eccaparadoxides mediterraneus are both widespread trilobite specie... more Eccaparadoxides? pradoanus and Eccaparadoxides mediterraneus are both widespread trilobite species described from the middle Cambrian of the Mediterranean region. Analysis based on a pooled sample of 500 specimens demonstrates that many of the characters that have been used to define these species show continuous variations, some of which are related to ontogeny. In addition, morphometric analyses of metric characters show that the two species cannot be distinguished on the basis of these characters either. Many of the characters studied herein are widely used in definitions and descriptions of other paradoxidid species, which suggests that the taxonomic classification of other paradoxidids may be oversplit.

Enrolled agnostids from Cambrian of Spain provide new insights about the mode of life in these forms

Bulletin of Geosciences

Enrolled agnostids have been known since the beginning of the nineteenth century but assemblages ... more Enrolled agnostids have been known since the beginning of the nineteenth century but assemblages with high number of enrolled specimens are rare. There are different hypotheses about the life habits of this arthropod group and why they enrolled. These include: a planktic or epiplanktic habit, with the rolled-up posture resulting from clapping cephalon and pygidium together, ectoparasitic habit or a sessile lifestyle, either attached to seaweeds or on the sea floor. Herein we describe two new assemblages from the middle Cambrian of Purujosa (Iberian Chains, North Spain) where agnostids are minor components of the fossil assemblages but occasionally appear enrolled. The taphonomic and sedimentological data suggest that these agnostids were suddenly buried and rolled up as a response to adverse palaeoenvironmental conditions. Their presence with typical benthic components supports a benthic mode of life for at least some species of agnostids.

New Middle Cambrian palaeoscolecid sclerites of Hadimopanella oezgueli from the Cantabrian Mountains, northern Spain

GFF

A new assemblage of palaeoscolecid sclerites preserving all the details of the (para)species Hadi... more A new assemblage of palaeoscolecid sclerites preserving all the details of the (para)species Hadimopanella oezgueli Gedik, 1977, including characteristic ornamentation, has been found in the Middle Cambrian Genestosa Member (Oville Formation) of the Cantabrian Mountains, northern Spain. The assemblage of sclerites shows a great morphological variability enabling mendation of its diagnosis. Some of them exhibit erosive facets as a result of reworking preceding definitive burial. One key specimen has lateral slits along the marginal brim, which represent a crown of eroded tubercles, and may be classified out the (para) genus Hadimopanella.

Articulation, interlocking devices and enrolment in Monkaspis daulis (Walcott, 1905) from the Guzhangian, middle Cambrian of Shandong Province, North China.

Lethaia

Monakspis daulis (Walcott, 1905) is the first enrolled trilobite to be documented from the Kushan... more Monakspis daulis (Walcott, 1905) is the first enrolled trilobite to be documented from the Kushan Formation (Guzhangian, Cambrian Series 3) of Northern China. It has a wide pygidium that allowed a sphaeroidal enrolment-type to be achieved, covering the cephalon and anterior trunk segments. M. daulis is micropygous but the pygidium is proportionally larger than that of many other Cambrian trilobites and there is a slightly variable number of segments in the trunk. Articulation structures are very well developed through the trunk but interlocking or coaptative devices are poorly developed with the exception of the terrace lines and a novel structure, a “posterior arch”, in the pygidium, which would have prevented shear. The absence of genal spines that would otherwise have inhibited sinking into the mud substrate may have enabled Monakspis daulis to use the enrolment procedure to excavate a hole in the sediment for taking shelter.

Gut content fossilization and evidence for detritus feeding habits in an enrolled trilobite from the Cambrian of China.

Lethaia

Enrolment was a major defensive strategy for trilobites which significantly contributed to their ... more Enrolment was a major defensive strategy for trilobites which significantly contributed to their evolutionary success. The ability to enroll also helped to constrain trilobites’ morphological evolution, which in part was driven by the need to improve this capability to encapsulate the soft parts of the body within the mineralized dorsal exoskeleton. Here we describe a unique example of gut content fossilization in an enrolled trilobite from the Cambrian of China, and we propose a taphonomic scenario that considers the possible implication of enrolment in this exceptional preservation. A microfacies analysis indicates that the specimen was entombed during an obrution event and remained intact due to limited infaunal activity. The encapsulation of the body did not prevent the decay of soft tissues, but it permitted the delicate gut content to be protected during diagenesis. In isolating the decaying soft tissues from the external environment, enrolment might also have favoured the establishment of microenvironmental conditions conducive to the precipitation of pyrite framboids. Within the gut, the formation of such crystals may have led to the consolidation of the ingested material. These results suggest that fossilized gut contents might be quite common in enrolled trilobites. Textural and compositional analyses reveal that the gut content is similar to the sediment surrounding the fossil except for the presence of pyrite framboids that indicate higher initial organic matter content. The complete enrolment of the body argues against an accidental ingestion of this material or a diagenetic origin for it. Accordingly, detritus feeding habits are inferred for this ptychopariid trilobite.

Humble origins for a successful strategy: complete enrolment in early Cambrian olenellid trilobites

Trilobites are typified by the behavioural and morphological ability to enrol their bodies, most ... more Trilobites are typified by the behavioural and morphological ability to enrol their bodies, most likely as a defence mechanism against adverse environmental conditions or predators. Although most trilobites could enrol at least partially, there is uncertainty on whether olenellids – among the most phylogenetically and stratigraphically basal representatives – could perform this behaviour due to their poorly caudalized trunk and scarcity of coaptative devices. Here we report complete – but not encapsulating – enrolment for the olenellid genus Mummaspis from the early Cambrian Mural Formation in Alberta, the earliest direct evidence of this strategy in the fossil record of polymerid trilobites. Complete enrolment in olenellids was achieved through a combination of ancestral morphological features, and thus provides new information on the character polarity associated with this key trilobite adaptation.

Revisión del enrollamiento en los trilobites del Cámbrico español y su implicación en la evolución de los trilobites (Revision of the enrolment in Spanish Cambrian trilobites and its implications in trilobite evolution)

Estudios Geológicos [online] http://dx.doi.org/10.3989/egeol http://estudiosgeol.revistas.csic.es... more

Thoracic structure and enrolment style in middle Cambrian Eccaparadoxides pradoanus presages caudalization of the derived trilobite trunk

Palaeontology, 2013

Abstract: The ability to enrol effectively evolved several times among trilobites. Here, we show... more Abstract: The ability to enrol effectively evolved several times among trilobites. Here, we show that, unlike most redlichiid trilobites that could not enrol, both morphotypes of Eccaparadoxides pradoanus from the middle Cambrian of Spain enrolled so as to enclose most of the ventral surface beneath the exoskeleton and possessed specialized articulating devices that facilitated this behaviour. The holaspid thorax of all E. pradoanus was divided into two principal regions. The boundary between these marked a transition from anterior segments with short pleural spines, fulcra and ridge-and-groove inner pleural regions to posterior segments with longer, acuminate pleural spines that lack fulcra and inner pleural regions. Devices that aid articulation, such as fulcra with short articulating pleural surfaces, the petaloid articulating facet and long articulating half rings, are concentrated in the anterior region. These features, and the large number of specimens preserved in various degrees of enrolment, suggest an enrolment procedure in which the rear part of the trunk, containing both the posterior thorax and the pygidium, rotated as a single unit without significant internal flexure. As these posterior trunk articulations were apparently not required to permit enrolment, concentrating flexure in the anterior may have presaged the caudalized condition seen in many derived trilobite groups that encapsulated, in which a larger proportion of the trunk segments were allocated to the mature pygidium, and therefore unable to articulate.

A new Alokistocaridae Resser, 1939 (Trilobita) from the middle Cambrian of Spain

Geobios, 2012

A new trilobite species, Schopfaspis? graciai, from the middle Cambrian of Spain is the first mem... more A new trilobite species, Schopfaspis? graciai, from the middle Cambrian of Spain is the first member of Alokistocaridae reported from west Gondwana. A cladistic analysis of this trilobite and other Gondwanan trilobites of possible alokistocarid affinities (Schopfaspis granulosa, Chelidonocephalus anatolicus, Derikaspis toluni, Kounamkites multiformis) suggests that this family can be divided into two subfamilies: Alokistocarinae and Altiocculinae. Schopfaspis? graciai nov. sp. and Schopfaspis granulosa are assigned to the subfamily Altiocculinae laying in a more basal position than Altiocculus species. The cladistic analysis also demonstrates a possible relationship of Chelidonocephalus anatolicus and Derikaspis toluni with Alokistocaridae. Enrolment is analysed in this new trilobite describing novelties in the ventral surface of the cephalon which allowed interlocking of the trunk and cephalon in a discoidal enrolment-type.

Exoskeletal abnormalities in paradoxidid trilobites from the Cambrian of Spain, and a new type of bite trace

Bulletin of Geoscience, 2011

Exoskeletal abnormalities in middle Cambrian paradoxidid trilobites from Purujosa (Eastern Iberia... more Exoskeletal abnormalities in middle Cambrian paradoxidid trilobites from Purujosa (Eastern Iberian Chain, NE Spain) are herein analyzed for the first time. Two distinct types are reported. The first is represented by triangular or asymmetrical V-to W-shaped breaks on margins of isolated sclerites (cranidia, free cheeks and hypostomes). The second group is represented by shortened thoracic pleural spines in complete or nearly complete individuals. Possible causes of these injuries are discussed, but in some cases a single cause/effect explanation is not apparent. A new ichnotaxon, Mandibulichnus serratus nov. ichnogen., nov. ichnosp., is erected to refer to serrated breakage of the margins of isolated trilobite sclerites produced by active predation or scavenging. •

Correlation between the base of Drumian Stage and the base of middle Caesaraugustan Stage in the Iberian Chains (NE, Spain).

Bulletin of Geoscience, 2011

Purujosa trilobite assemblage and the evolution of trilobite enrollment

Lethaia, 2011

Localities bearing abundant enrolled Cambrian trilobites are extremely rare, but here we report a... more Localities bearing abundant enrolled Cambrian trilobites are extremely rare, but here we report a new and exceptional such assemblage with a high diversity of enrolled specimens from the middle Cambrian of Spain. This novel find demonstrates that encapsulated enrollment was a behavioral response available to many of the early benthic trilobite morphotypes. This result provides a new perspective for reviewing the evolution of trilobite enrollment through the Paleozoic. We find a significant and consistent increase in the proportion of enrolled trilobites within assemblages bearing abundant articulated trilobites. Similarly, the mean number of coaptative devices also increased progressively during the Paleozoic. Such devices likely provided later enrolled trilobites with greater structural integrity, and may support an escalatory model of trilobite defense evolution. Likewise, environmental circumstances favoring the preservation of enrolled trilobites may have become more common during post-Cambrian time.

Sphaeroidal enrolment in middle Cambrian solenopleuropsine

Lethaia, 2010

Fifty specimens belonging to species of Solenopleuropsis and Pardailhania from Spain and France d... more Fifty specimens belonging to species of Solenopleuropsis and Pardailhania from Spain and France demonstrate sphaeroidal enrolment in Cambrian trilobites for the first time. These solenopleuropsines show novel coaptative structures in different regions of the exoskeleton: in the cephalon there are vincular furrows and notches; in the thorax an articulating facet is developed at the pleural margins, with a ball and socket connection on the adaxial most portion, and an articulating half-ring axially; the pygidium possesses an articulating facet. The interaction of these coaptative structures resulted in a sphaeroidal enrolment that was a progressive act from the first articulation between the occipital ring and the first segment to the pygidial articulating facet. A similar type of sphaeroidal enrolment is observed in the Devonian trilobite Phacops. Both Cambrian and Devonian trilobites developed a vincular furrow in the ventral surface of the cephalon to close their bodies tightly. In both cases, this is probably a convergent adaptation to protect against predators and obrution. Indeed, the enrolled trilobites are very common in obrution deposits restricted to shallow and soft muddy substrates

Enrolment in Conocoryphe heberti Munier-Chalmas & Bergeron, 1889 (Middle Cambrian, Iberian Chain, NE Spain) and coaptive structures within family Conocoryphidae

Estudios Geologicos, 2009

Enrolled Conocoryphe heberti is described with detail and compared with the conocoryphid Occathar... more Enrolled Conocoryphe heberti is described with detail and compared with the conocoryphid Occatharia sdzuyi, both very abundant in the middle Cambrian from the Mediterranean subprovince. Both show different morphological novelties very useful to enrol and interlock the trilobite body. The morphological
study allows us to recognize coaptative devices that show the possibility of a tight encapsulation enrolment. The coaptative devices are analyzed in cephalons, pigidia and almost completed outstretched trilobites of Bailiella levyi, Bailiaspis souchoni and Parabailiella languedocensis belonging to the same family. The coaptative structures analyzed show enough variability in cephalons and pigidia that allow suggesting several enrolment types within conocoryphids.

Lower and Middle Cambrian trilobites of selected localities in Cadenas Ibéricas (NE Spain)

Fourth International Trilobite Conference. Trilo 08. Toledo, Spain, 2008. Post-Conference Field Trip. Lower and Middle Cambrian trilobites of selected localities in Cadenas Ibéricas (NE Spain), 2008

Primera edición, primera impresión 52 pp.; 22 il.; 15,0 x 21,0 cm ISBN: 978-84-92522-01-9 Ficha c... more Primera edición, primera impresión 52 pp.; 22 il.; 15,0 x 21,0 cm ISBN: 978-84-92522-01-9 Ficha catalográfica Ninguna parte de este libro puede ser reproducida o transmitida en cualquier forma o por cualquier medio sin el previo permiso por escrito del editor. / No part of this book may be reproduced or transmitted by any mean without the previous, written permission from the publisher. Cover: view to the Southwest of Middle Cambrian outcrops at Rambla de Valdemiedes, near the village of Murero (Zaragoza, Aragón, NE Spain). Title page: sketch of the basal Middle Cambrian trilobite Acadoparadoxides mureroensis Sdzuy, 1959. Impreso en España (U. E.) -Printed in Spain CDU: 56 (460.224) (036) 565.393 56.017.2 56.017.4

Intraspecific variability in paradoxidid trilobites from the Purujosa trilobite

Acta Palaeontologica Polonica, 2013

Eccaparadoxides? pradoanus and Eccaparadoxides mediterraneus are both widespread trilobite specie... more Eccaparadoxides? pradoanus and Eccaparadoxides mediterraneus are both widespread trilobite species described from the middle Cambrian of the Mediterranean region. Analysis based on a pooled sample of 500 specimens demonstrates that many of the characters that have been used to define these species show continuous variations, some of which are related to ontogeny. In addition, morphometric analyses of metric characters show that the two species cannot be distinguished on the basis of these characters either. Many of the characters studied herein are widely used in definitions and descriptions of other paradoxidid species, which suggests that the taxonomic classification of other paradoxidids may be oversplit.

Enrolled agnostids from Cambrian of Spain provide new insights about the mode of life in these forms

Bulletin of Geosciences

Enrolled agnostids have been known since the beginning of the nineteenth century but assemblages ... more Enrolled agnostids have been known since the beginning of the nineteenth century but assemblages with high number of enrolled specimens are rare. There are different hypotheses about the life habits of this arthropod group and why they enrolled. These include: a planktic or epiplanktic habit, with the rolled-up posture resulting from clapping cephalon and pygidium together, ectoparasitic habit or a sessile lifestyle, either attached to seaweeds or on the sea floor. Herein we describe two new assemblages from the middle Cambrian of Purujosa (Iberian Chains, North Spain) where agnostids are minor components of the fossil assemblages but occasionally appear enrolled. The taphonomic and sedimentological data suggest that these agnostids were suddenly buried and rolled up as a response to adverse palaeoenvironmental conditions. Their presence with typical benthic components supports a benthic mode of life for at least some species of agnostids.

New Middle Cambrian palaeoscolecid sclerites of Hadimopanella oezgueli from the Cantabrian Mountains, northern Spain

GFF

A new assemblage of palaeoscolecid sclerites preserving all the details of the (para)species Hadi... more A new assemblage of palaeoscolecid sclerites preserving all the details of the (para)species Hadimopanella oezgueli Gedik, 1977, including characteristic ornamentation, has been found in the Middle Cambrian Genestosa Member (Oville Formation) of the Cantabrian Mountains, northern Spain. The assemblage of sclerites shows a great morphological variability enabling mendation of its diagnosis. Some of them exhibit erosive facets as a result of reworking preceding definitive burial. One key specimen has lateral slits along the marginal brim, which represent a crown of eroded tubercles, and may be classified out the (para) genus Hadimopanella.

Articulation, interlocking devices and enrolment in Monkaspis daulis (Walcott, 1905) from the Guzhangian, middle Cambrian of Shandong Province, North China.

Lethaia

Monakspis daulis (Walcott, 1905) is the first enrolled trilobite to be documented from the Kushan... more Monakspis daulis (Walcott, 1905) is the first enrolled trilobite to be documented from the Kushan Formation (Guzhangian, Cambrian Series 3) of Northern China. It has a wide pygidium that allowed a sphaeroidal enrolment-type to be achieved, covering the cephalon and anterior trunk segments. M. daulis is micropygous but the pygidium is proportionally larger than that of many other Cambrian trilobites and there is a slightly variable number of segments in the trunk. Articulation structures are very well developed through the trunk but interlocking or coaptative devices are poorly developed with the exception of the terrace lines and a novel structure, a “posterior arch”, in the pygidium, which would have prevented shear. The absence of genal spines that would otherwise have inhibited sinking into the mud substrate may have enabled Monakspis daulis to use the enrolment procedure to excavate a hole in the sediment for taking shelter.

Gut content fossilization and evidence for detritus feeding habits in an enrolled trilobite from the Cambrian of China.

Lethaia

Enrolment was a major defensive strategy for trilobites which significantly contributed to their ... more Enrolment was a major defensive strategy for trilobites which significantly contributed to their evolutionary success. The ability to enroll also helped to constrain trilobites’ morphological evolution, which in part was driven by the need to improve this capability to encapsulate the soft parts of the body within the mineralized dorsal exoskeleton. Here we describe a unique example of gut content fossilization in an enrolled trilobite from the Cambrian of China, and we propose a taphonomic scenario that considers the possible implication of enrolment in this exceptional preservation. A microfacies analysis indicates that the specimen was entombed during an obrution event and remained intact due to limited infaunal activity. The encapsulation of the body did not prevent the decay of soft tissues, but it permitted the delicate gut content to be protected during diagenesis. In isolating the decaying soft tissues from the external environment, enrolment might also have favoured the establishment of microenvironmental conditions conducive to the precipitation of pyrite framboids. Within the gut, the formation of such crystals may have led to the consolidation of the ingested material. These results suggest that fossilized gut contents might be quite common in enrolled trilobites. Textural and compositional analyses reveal that the gut content is similar to the sediment surrounding the fossil except for the presence of pyrite framboids that indicate higher initial organic matter content. The complete enrolment of the body argues against an accidental ingestion of this material or a diagenetic origin for it. Accordingly, detritus feeding habits are inferred for this ptychopariid trilobite.

Humble origins for a successful strategy: complete enrolment in early Cambrian olenellid trilobites

Trilobites are typified by the behavioural and morphological ability to enrol their bodies, most ... more Trilobites are typified by the behavioural and morphological ability to enrol their bodies, most likely as a defence mechanism against adverse environmental conditions or predators. Although most trilobites could enrol at least partially, there is uncertainty on whether olenellids – among the most phylogenetically and stratigraphically basal representatives – could perform this behaviour due to their poorly caudalized trunk and scarcity of coaptative devices. Here we report complete – but not encapsulating – enrolment for the olenellid genus Mummaspis from the early Cambrian Mural Formation in Alberta, the earliest direct evidence of this strategy in the fossil record of polymerid trilobites. Complete enrolment in olenellids was achieved through a combination of ancestral morphological features, and thus provides new information on the character polarity associated with this key trilobite adaptation.

Revisión del enrollamiento en los trilobites del Cámbrico español y su implicación en la evolución de los trilobites (Revision of the enrolment in Spanish Cambrian trilobites and its implications in trilobite evolution)

Estudios Geológicos [online] http://dx.doi.org/10.3989/egeol http://estudiosgeol.revistas.csic.es... more

Thoracic structure and enrolment style in middle Cambrian Eccaparadoxides pradoanus presages caudalization of the derived trilobite trunk

Palaeontology, 2013

Abstract: The ability to enrol effectively evolved several times among trilobites. Here, we show... more Abstract: The ability to enrol effectively evolved several times among trilobites. Here, we show that, unlike most redlichiid trilobites that could not enrol, both morphotypes of Eccaparadoxides pradoanus from the middle Cambrian of Spain enrolled so as to enclose most of the ventral surface beneath the exoskeleton and possessed specialized articulating devices that facilitated this behaviour. The holaspid thorax of all E. pradoanus was divided into two principal regions. The boundary between these marked a transition from anterior segments with short pleural spines, fulcra and ridge-and-groove inner pleural regions to posterior segments with longer, acuminate pleural spines that lack fulcra and inner pleural regions. Devices that aid articulation, such as fulcra with short articulating pleural surfaces, the petaloid articulating facet and long articulating half rings, are concentrated in the anterior region. These features, and the large number of specimens preserved in various degrees of enrolment, suggest an enrolment procedure in which the rear part of the trunk, containing both the posterior thorax and the pygidium, rotated as a single unit without significant internal flexure. As these posterior trunk articulations were apparently not required to permit enrolment, concentrating flexure in the anterior may have presaged the caudalized condition seen in many derived trilobite groups that encapsulated, in which a larger proportion of the trunk segments were allocated to the mature pygidium, and therefore unable to articulate.

A new Alokistocaridae Resser, 1939 (Trilobita) from the middle Cambrian of Spain

Geobios, 2012

A new trilobite species, Schopfaspis? graciai, from the middle Cambrian of Spain is the first mem... more A new trilobite species, Schopfaspis? graciai, from the middle Cambrian of Spain is the first member of Alokistocaridae reported from west Gondwana. A cladistic analysis of this trilobite and other Gondwanan trilobites of possible alokistocarid affinities (Schopfaspis granulosa, Chelidonocephalus anatolicus, Derikaspis toluni, Kounamkites multiformis) suggests that this family can be divided into two subfamilies: Alokistocarinae and Altiocculinae. Schopfaspis? graciai nov. sp. and Schopfaspis granulosa are assigned to the subfamily Altiocculinae laying in a more basal position than Altiocculus species. The cladistic analysis also demonstrates a possible relationship of Chelidonocephalus anatolicus and Derikaspis toluni with Alokistocaridae. Enrolment is analysed in this new trilobite describing novelties in the ventral surface of the cephalon which allowed interlocking of the trunk and cephalon in a discoidal enrolment-type.

Exoskeletal abnormalities in paradoxidid trilobites from the Cambrian of Spain, and a new type of bite trace

Bulletin of Geoscience, 2011

Exoskeletal abnormalities in middle Cambrian paradoxidid trilobites from Purujosa (Eastern Iberia... more Exoskeletal abnormalities in middle Cambrian paradoxidid trilobites from Purujosa (Eastern Iberian Chain, NE Spain) are herein analyzed for the first time. Two distinct types are reported. The first is represented by triangular or asymmetrical V-to W-shaped breaks on margins of isolated sclerites (cranidia, free cheeks and hypostomes). The second group is represented by shortened thoracic pleural spines in complete or nearly complete individuals. Possible causes of these injuries are discussed, but in some cases a single cause/effect explanation is not apparent. A new ichnotaxon, Mandibulichnus serratus nov. ichnogen., nov. ichnosp., is erected to refer to serrated breakage of the margins of isolated trilobite sclerites produced by active predation or scavenging. •

Correlation between the base of Drumian Stage and the base of middle Caesaraugustan Stage in the Iberian Chains (NE, Spain).

Bulletin of Geoscience, 2011

Purujosa trilobite assemblage and the evolution of trilobite enrollment

Lethaia, 2011

Localities bearing abundant enrolled Cambrian trilobites are extremely rare, but here we report a... more Localities bearing abundant enrolled Cambrian trilobites are extremely rare, but here we report a new and exceptional such assemblage with a high diversity of enrolled specimens from the middle Cambrian of Spain. This novel find demonstrates that encapsulated enrollment was a behavioral response available to many of the early benthic trilobite morphotypes. This result provides a new perspective for reviewing the evolution of trilobite enrollment through the Paleozoic. We find a significant and consistent increase in the proportion of enrolled trilobites within assemblages bearing abundant articulated trilobites. Similarly, the mean number of coaptative devices also increased progressively during the Paleozoic. Such devices likely provided later enrolled trilobites with greater structural integrity, and may support an escalatory model of trilobite defense evolution. Likewise, environmental circumstances favoring the preservation of enrolled trilobites may have become more common during post-Cambrian time.

Sphaeroidal enrolment in middle Cambrian solenopleuropsine

Lethaia, 2010

Fifty specimens belonging to species of Solenopleuropsis and Pardailhania from Spain and France d... more Fifty specimens belonging to species of Solenopleuropsis and Pardailhania from Spain and France demonstrate sphaeroidal enrolment in Cambrian trilobites for the first time. These solenopleuropsines show novel coaptative structures in different regions of the exoskeleton: in the cephalon there are vincular furrows and notches; in the thorax an articulating facet is developed at the pleural margins, with a ball and socket connection on the adaxial most portion, and an articulating half-ring axially; the pygidium possesses an articulating facet. The interaction of these coaptative structures resulted in a sphaeroidal enrolment that was a progressive act from the first articulation between the occipital ring and the first segment to the pygidial articulating facet. A similar type of sphaeroidal enrolment is observed in the Devonian trilobite Phacops. Both Cambrian and Devonian trilobites developed a vincular furrow in the ventral surface of the cephalon to close their bodies tightly. In both cases, this is probably a convergent adaptation to protect against predators and obrution. Indeed, the enrolled trilobites are very common in obrution deposits restricted to shallow and soft muddy substrates

Enrolment in Conocoryphe heberti Munier-Chalmas & Bergeron, 1889 (Middle Cambrian, Iberian Chain, NE Spain) and coaptive structures within family Conocoryphidae

Estudios Geologicos, 2009

Enrolled Conocoryphe heberti is described with detail and compared with the conocoryphid Occathar... more Enrolled Conocoryphe heberti is described with detail and compared with the conocoryphid Occatharia sdzuyi, both very abundant in the middle Cambrian from the Mediterranean subprovince. Both show different morphological novelties very useful to enrol and interlock the trilobite body. The morphological
study allows us to recognize coaptative devices that show the possibility of a tight encapsulation enrolment. The coaptative devices are analyzed in cephalons, pigidia and almost completed outstretched trilobites of Bailiella levyi, Bailiaspis souchoni and Parabailiella languedocensis belonging to the same family. The coaptative structures analyzed show enough variability in cephalons and pigidia that allow suggesting several enrolment types within conocoryphids.

Lower and Middle Cambrian trilobites of selected localities in Cadenas Ibéricas (NE Spain)

Fourth International Trilobite Conference. Trilo 08. Toledo, Spain, 2008. Post-Conference Field Trip. Lower and Middle Cambrian trilobites of selected localities in Cadenas Ibéricas (NE Spain), 2008

Primera edición, primera impresión 52 pp.; 22 il.; 15,0 x 21,0 cm ISBN: 978-84-92522-01-9 Ficha c... more Primera edición, primera impresión 52 pp.; 22 il.; 15,0 x 21,0 cm ISBN: 978-84-92522-01-9 Ficha catalográfica Ninguna parte de este libro puede ser reproducida o transmitida en cualquier forma o por cualquier medio sin el previo permiso por escrito del editor. / No part of this book may be reproduced or transmitted by any mean without the previous, written permission from the publisher. Cover: view to the Southwest of Middle Cambrian outcrops at Rambla de Valdemiedes, near the village of Murero (Zaragoza, Aragón, NE Spain). Title page: sketch of the basal Middle Cambrian trilobite Acadoparadoxides mureroensis Sdzuy, 1959. Impreso en España (U. E.) -Printed in Spain CDU: 56 (460.224) (036) 565.393 56.017.2 56.017.4