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  • 1
    In: Geobios, Elsevier BV, ( 2023-8)
    Type of Medium: Online Resource
    ISSN: 0016-6995
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 2098288-4
    SSG: 13
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  • 2
    In: Papers in Palaeontology, Wiley, Vol. 7, No. 2 ( 2021-05), p. 839-859
    Abstract: Trilobite development has been intensively explored during the past decades, but information on ancestral character combinations in the early developmental stages of trilobites remains unknown. Trilobites of the superfamily Olenelloidea are one of the earliest diverging groups. Study of their development coupled with the development of other early diverging trilobite groups can provide information on the ancestral morphology of trilobite early stages. Herein we describe numerous well‐preserved specimens of the olenelloid trilobite Fritzolenellus lapworthi . The earliest stages have circular cephala bearing intergenal spines and lacking genal spines. During subsequent development, morphological changes involve the modification of the cephalic shape from circular to semicircular, expansion of the frontal glabellar lobe, gradual shortening of intergenal spines and origin and prolongation of genal spines. Trunk development of Fritzolenellus suggests that macropleurae and macrospine development are two independent processes and that the origin of the opisthotrunk is linked with the onset of phase 5 of cephalic development. The morphology of the early developmental stages of Fritzolenellus and of some related taxa differs in many aspects from the morphology of equivalent stages of some other members of Olenelloidea. Consequently, two basic morphotypes are recognized during the early development of Olenelloidea: the Fritzolenellus and the Olenellus morphotypes. Comparison with Fallotaspidoidea and Redlichiina indicates that early developmental stages of these taxa share character combinations that are typical for the Fritzolenellus morphotype. Such a comparison suggests that characters defining the Fritzolenellus morphotype are ancestral for Trilobita. The Olenellus morphotype is probably a derived condition within Olenelloidea and might be related to predator deterrence.
    Type of Medium: Online Resource
    ISSN: 2056-2799 , 2056-2802
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2807178-5
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  • 3
    Online Resource
    Online Resource
    Frontiers Media SA ; 2023
    In:  Frontiers in Ecology and Evolution Vol. 11 ( 2023-10-3)
    In: Frontiers in Ecology and Evolution, Frontiers Media SA, Vol. 11 ( 2023-10-3)
    Abstract: Euchelicerata is a diverse group encompassing Xiphosura, Chasmataspidida, Eurypterida, and Arachnida. Xiphosura represents an extant group with a rich fossil record dating back to the Ordovician period. Xiphosurans are often referred to as “living fossils” due to their seemingly unchanged morphology over millions of years. Numerous studies have contributed to the understanding of xiphosuran development, revealing changes in the timing and rate of their growth. These changes have been mainly associated with the freshwater invasion of early xiphosuran forms. However, limited research has been conducted to compare the developmental patterns of xiphosurans with other euchelicerates inhabiting aquatic environments. Methods This study compares the developmental patterns of xiphosurans with that of the fossil clades of eurypterids and chasmataspidids. By incorporating environmental and phylogenetic information within ancestral state reconstruction analyses, and then testing different evolutionary scenarios, the influence of the environment on the evolution of developmental patterns of euchelicerates is examined. Results The results confirm that the developmental changes in Xiphosura throughout their evolutionary history are correlated with the exploitation of different environments. However, the inclusion of eurypterids and chasmataspidids indicates that the entirety of changes seen for Xiphosura represent only a small portion of the total variability recovered for euchelicerates. Discussion Our results emphasize the importance of considering phylogenetic relationships and outgroup comparisons to understand the evolutionary dynamics of Xiphosura.
    Type of Medium: Online Resource
    ISSN: 2296-701X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
    detail.hit.zdb_id: 2745634-1
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  • 4
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 2015
    In:  Paleobiology Vol. 41, No. 4 ( 2015-09), p. 554-569
    In: Paleobiology, Cambridge University Press (CUP), Vol. 41, No. 4 ( 2015-09), p. 554-569
    Abstract: Arthropods are known to display a variable number of eye lenses and this number mostly increases during their development. In trilobites, most species possessing schizochroal eyes exhibit a notable intraspecific variation in the number of dorso ventral files of eye lenses that can be age related (i.e., growth) or not (i.e., living environment). Several previous studies have shown that some trilobite groups (e.g. phacopids) tend to have fewer lenses/files in representatives from the deeper habitats than those from shallower habitats. In this study, we analyzed the pattern of variation in the number of dorso ventral files of eye lenses in two Devonian phacopid trilobites from the Prague Basin of the Czech Republic. We quantified their intraspecific variability. To better understand the patterning, we compared more than 120 individuals. Data first reveal evidence of a bimodal distribution of lens/file number without intermediate forms among each of two studied populations of Prokops prokopi (Chlupáč, 1971) and throughout the ontogeny of Pedinopariops insequens (Chlupáč, 1977). Our results indicate that caution must be taken for taxonomical affiliation and biodiversity analyses of taxa in which the intraspecific variability is unclear. Additionally, we investigated possible relations of these bimodalities to the stratigraphical position of studied populations and to the paleoenvironment. In Prokops prokopi , a slightly different age of both populations, together with supposed differences in the local environments can be responsible for observed variability. In Pedinopariops insequens , stress conditions possibly related to the approaching onset of the Basal Choteč Event can be responsible for surprising intrapopulation variability. We speculate that the stress conditions could cause a bimodal selection and possibly also the change of ontogenetic trajectory within this species. Pedinopariops insequens was the only phacopid in the Prague Basin that crosses the Lower/Middle Devonian boundary and survived also the onset of Basal Choteč Event.
    Type of Medium: Online Resource
    ISSN: 0094-8373 , 1938-5331
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2015
    detail.hit.zdb_id: 2052186-8
    SSG: 12
    SSG: 13
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  • 5
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 2018
    In:  Paleobiology Vol. 44, No. 4 ( 2018-11), p. 638-659
    In: Paleobiology, Cambridge University Press (CUP), Vol. 44, No. 4 ( 2018-11), p. 638-659
    Abstract: A large sample of postembryonic specimens of Dalmanitina proaeva elfrida and D. socialis from the Upper Ordovician (Sandbian to Katian) Prague Basin allows for the first reasonably complete ontogenetic sequence of Dalmanitoidea (Phacopina). The material provides an abundance of morphological information, including well-preserved marginal spines in protaspides and meraspides, and hypostome external surfaces throughout. The development of D. proaeva elfrida is unusual due to variability in timing of the first trunk articulation. This broadens our developmental understanding of Phacopina, a diverse group of phacopid trilobites, and also allows us to study the evolution of their specializations in exoskeletal molting behavior. Adult phacopines, unlike most other trilobites, had fused facial sutures. This means that rather than molting through the sutural gape mode, characterized by opening of the facial sutures and separation of the librigenae, they disarticulated the entire cephalon in Salter’s mode of molting. For other phacopine clades (Phacopoidea) the transition to Salter’s mode occurs during the meraspid period or at the onset of holaspis, and its developmental timing is intraspecifically fixed. However, owing to the large sample size, we can see that facial suture fusion likely occurred later in Dalmanitina , usually during the holaspid period, and was intraspecifically variable with holaspides of varying sizes showing unfused sutures. Further, D. proaeva elfrida specimens showed an initial librigenal–rostral plate fusion event, where the librigenae began as separate entities but appear fused with the rostral plate as one structure (the “lower cephalic unit”) from M1, and are discarded as such during molting. Dalmanitoidea is considered to represent the first phacopine divergence, occurring earliest in the fossil record. This material therefore provides insight into how linked morphologies and behaviors evolved, potentially suggesting the timing of facial suture fusion in Phacopina moved earlier during development and became more intraspecifically fixed over geological time.
    Type of Medium: Online Resource
    ISSN: 0094-8373 , 1938-5331
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2018
    detail.hit.zdb_id: 2052186-8
    SSG: 12
    SSG: 13
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  • 6
    Online Resource
    Online Resource
    National Museum, Czech Republic ; 2016
    In:  Fossil Imprint Vol. 72, No. 3-4 ( 2016-12-30), p. 161-171
    In: Fossil Imprint, National Museum, Czech Republic, Vol. 72, No. 3-4 ( 2016-12-30), p. 161-171
    Abstract: The discovery of the partially enrolled specimens of large, late holaspid specimens of paradoxidid trilobites Paradoxides paradoxissimus gracilis, Hydrocephalus minor and Acadoparadoxides cf. sacheri, together with the investigation of functional morphology of their thorax suggest that these arthropods were able to enclose their bodies. The different morphology of thoracic tergites and different outline of the trunk implies different enrollment styles in these species. Consequently, it is possible to distinguish four styles of enrollment within the family Paradoxididae. This variability of enrollment styles not only extends our knowledge about enrollment of paradoxidid trilobites, but also widens our view to diverse protective adaptations in closely related taxa of one family.
    Type of Medium: Online Resource
    ISSN: 2533-4069 , 2533-4050
    Language: English
    Publisher: National Museum, Czech Republic
    Publication Date: 2016
    detail.hit.zdb_id: 2889036-X
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  • 7
    Online Resource
    Online Resource
    Elsevier BV ; 2021
    In:  Arthropod Structure & Development Vol. 63 ( 2021-07), p. 101059-
    In: Arthropod Structure & Development, Elsevier BV, Vol. 63 ( 2021-07), p. 101059-
    Type of Medium: Online Resource
    ISSN: 1467-8039
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 2001498-3
    SSG: 12
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  • 8
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2022
    In:  Biological Journal of the Linnean Society Vol. 136, No. 1 ( 2022-04-22), p. 155-172
    In: Biological Journal of the Linnean Society, Oxford University Press (OUP), Vol. 136, No. 1 ( 2022-04-22), p. 155-172
    Abstract: Records of evolutionary stasis over time are central to uncovering large-scale evolutionary modes, whether by long-term gradual change or via enduring stability punctuated by rapid shifts. The key to this discussion is to identify and examine groups with long fossil records that, ideally, extend to the present day. One group often regarded as the quintessential example of stasis is Xiphosurida, the horseshoe crabs. However, when, how and, particularly, why stasis arose in xiphosurids remain fundamental, but complex, questions. Here, we explore the protracted history of fossil and living xiphosurids and demonstrate two levels of evolutionary stability: developmental stasis since at least the Pennsylvanian and shape stasis since the Late Jurassic. Furthermore, shape and diversity are punctuated by two high-disparity episodes during the Carboniferous and Triassic – transitions that coincide with forays into habitation of marginal environments. In an exception to these general patterns, body size increased gradually over this period and, thus, cannot be described under the same, often-touted, static models of evolution. Therefore, we demonstrate that evolutionary stasis can be modular and fixed within the same group at different periods and in different biological traits, while other traits experience altogether different evolutionary modes. This mosaic in the tempo and mode of evolution is not unique to Xiphosurida but likely reflects variable mechanisms acting on biological traits, for example transitions in life modes, niche occupation and major evolutionary radiations.
    Type of Medium: Online Resource
    ISSN: 0024-4066 , 1095-8312
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 1461865-5
    detail.hit.zdb_id: 220623-7
    SSG: 12
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  • 9
    Online Resource
    Online Resource
    Polska Akademia Nauk Instytut Paleobiologii (Institute of Paleobiology, Polish Academy of Sciences) ; 2021
    In:  Acta Palaeontologica Polonica Vol. 66 ( 2021)
    In: Acta Palaeontologica Polonica, Polska Akademia Nauk Instytut Paleobiologii (Institute of Paleobiology, Polish Academy of Sciences), Vol. 66 ( 2021)
    Type of Medium: Online Resource
    ISSN: 0567-7920
    Language: Unknown
    Publisher: Polska Akademia Nauk Instytut Paleobiologii (Institute of Paleobiology, Polish Academy of Sciences)
    Publication Date: 2021
    detail.hit.zdb_id: 2161118-X
    SSG: 13
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  • 10
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 12, No. 1 ( 2022-12-13)
    Abstract: The Fezouata Biota (Morocco) is a unique Early Ordovician fossil assemblage. The discovery of this biota revolutionized our understanding of Earth’s early animal diversifications—the Cambrian Explosion and the Ordovician Radiation—by suggesting an evolutionary continuum between both events. Herein, we describe Taichoute, a new fossil locality from the Fezouata Shale. This locality extends the temporal distribution of fossil preservation from this formation into the upper Floian, while also expanding the range of depositional environments to more distal parts of the shelf. In Taichoute, most animals were transported by density flows, unlike the in-situ preservation of animals recovered in previously investigated Fezouata sites. Taichoute is dominated by three-dimensionally preserved, and heavily sclerotized fragments of large euarthropods—possibly representing nektobenthic/nektic bivalved taxa and/or hurdiid radiodonts. Resolving whether this dominance reflects a legitimate aspect of the original ecosystem or a preservational bias requires an in-depth assessment of the environmental conditions at this site. Nevertheless, Taichoute provides novel preservational and palaeontological insights during a key evolutionary transition in the history of life on Earth.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2615211-3
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