Positional specification in the segmental growth pattern of an early arthropod

Fusco, Giuseppe; Hong, Paul S.; Hughes, Nigel C.

doi:10.1098/rspb.2013.3037

Cited by 25 publications

(59 citation statements)

References 35 publications

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“…Several recent studies of trilobite growth have also been based on material from the site (Fusco et al 2004(Fusco et al , 2014Hughes & Chapman 1995) with a particular focus on the development of Aulacopleura koninckii (Barrande, 1846). To date, documentation of the palaeoecology and palaeoenvironment of the Na Černid-lech Hill site has largely been limited to lists of faunal occurrence (e.g.…”

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confidence: 99%

The depositional environment and taphonomy of the Homerian “Aulacopleura shales” fossil assemblage near Loděnice, Czech Republic (Prague Basin, Perunican microcontinent)

Hughes¹,

Kříž²,

Macquaker³

et al. 2014

Bull. Geosci.

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Excavation of Joachim Barrande's classic fossil locality of the "Aulacopleura shales" exposed on Na Černidlech Hill, near Loděnice reveals that most specimens were recovered from a 1.4 m interval exposed in "Barrande's pits". These are located at the eastern end of a 0.4 km trench dug in the mid 1800's to expose the interval along strike. Over an hundred bedding planes occur within the 1.4 m interval, and thousands of articulated trilobites have been collected at the site. Individual bed surfaces vary in the density, size, and taxonomic composition of the fossils contained. Some preserve a diverse benthic shelly fauna, others are almost exclusively dominated by the trilobite Aulacopleura koninckii, and a third variety is apparently barren of all shelly fossils. Isolated sclerites of A. koninckii are rare, and on almost all bedding surfaces exoskeletons are predominantly partially articulated and lack both alignment and sclerite fragmentation. The occurrence of A. koninckii conforms in many ways to the characteristics of a Type I trilobite lagerstätte of Brett et al. (2012). The presence of enrolled A. koninckii suggests that final burial may have resulted from relatively rapid obrution, although the condition of partial articulation indicates that many carcasses or exuviae partially disaggregated before burial. The mean size and density of A. koninckii specimens varies markedly among bedding planes, with some assemblages entirely comprised of juveniles, suggesting that notably dense trilobite clustering was not restricted only to reproductively mature individuals. The presence of multiple clusters of different mean specimen size partly accounts from the unusually comprehensive record of the articulated meraspid and holaspid ontogeny of this species at this locality. Limited bioturbation suggests a dysoxic substrate, and the olenimorphic form and distribution of A. koninckii, combined with a lack of encrustation or predation upon it, suggests that this species may have periodically bloomed in abundance at particular oxygen concentrations that largely excluded other skeletonized benthos. Some bedding plane assemblages might represent mass mortality events, perhaps as available oxygen passed below levels necessary to maintain the metabolism of A. koninckii. •

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confidence: 99%

The depositional environment and taphonomy of the Homerian “Aulacopleura shales” fossil assemblage near Loděnice, Czech Republic (Prague Basin, Perunican microcontinent)

Hughes¹,

Kříž²,

Macquaker³

et al. 2014

Bull. Geosci.

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“…In recent years, the combination of technologies from developmental biology and abundant genomic resources for a multitude of model and nonmodel organisms has greatly enriched our understanding of the genetic and developmental processes underlying organogenesis. This broad set of tools provides a new framework for testing hypotheses derived from paleontological findings, thereby forming an interdisciplinary research program with comparative genomics as well as genetic manipulation of embryonic development (12)(13)(14)(15).…”

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Organogenesis in deep time: A problem in genomics, development, and paleontology

Pieretti

Gehrke

Schneider

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The fossil record is a unique repository of information on major morphological transitions. Increasingly, developmental, embryological, and functional genomic approaches have also conspired to reveal evolutionary trajectory of phenotypic shifts. Here, we use the vertebrate appendage to demonstrate how these disciplines can mutually reinforce each other to facilitate the generation and testing of hypotheses of morphological evolution. We discuss classical theories on the origins of paired fins, recent data on regulatory modulations of fish fins and tetrapod limbs, and case studies exploring the mechanisms of digit loss in tetrapods. We envision an era of research in which the deep history of morphological evolution can be revealed by integrating fossils of transitional forms with direct experimentation in the laboratory via genome manipulation, thereby shedding light on the relationship between genes, developmental processes, and the evolving phenotype.fossil record | development | genomics | evolution | limb P aleontologists in recent decades have discovered a host of new taxa that reveal transitional stages in the evolution of birds, whales, mammals, tetrapods, frogs, salamanders, and arthropods (1-9). This pulse of discovery is not an accident, but the result of an elaboration of our ability to identify likely sites for fossil recovery by using increasingly refined phylogenies, stratigraphic maps, and geological records. Likewise, imaging techniques, such as highenergy CT, have opened up old and understudied fossil collections as new vehicles for discovery. With advances in both fieldwork and imaging, the discovery of the phenotypic basis for morphological innovation is at a critical moment in its long history: Novel perspectives on classical questions of anatomical evolution are within our reach.Fossils, when placed in a phylogenetic context, can reveal taxa with novel combinations of characters that could not be predicted by studying extant creatures alone. If we lacked fossil evidence of mammal-like reptiles, for example, then the physiological and morphological similarities of birds and mammals would likely be interpreted as homologies rather than examples of parallel evolution (e.g., the discredited "Haemothermia" clade) (10, 11). In addition to identifying solid taxonomic groupings, these same fossils reveal transitional series in the origin of the mammalian dentition, ear, and cranium (3). Our understanding of numerous other transformations, from the origin of birds to the origin of tetrapods, is seriously limited without the knowledge of extinct stem taxa.A rich fossil record permits us to document robustly supported transformation series in the evolution of an anatomical feature, organ system, or body plan. However, to understand the pattern and process of evolutionary transitions, paleontologists have increasingly turned their attention to development. In recent years, the combination of technologies from developmental biology and abundant genomic resources for a multitude of model and nonmodel organ...

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“…1A), which may reflect a gradient in growth rate along the trunk axis (9). The trunk is near parallel sided, tapering markedly only in the last three tergites (Fig.…”

Section: Significancementioning

confidence: 99%

Tiny individuals attached to a new Silurian arthropod suggest a unique mode of brood care

Sutton

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The ∼430-My-old Herefordshire, United Kingdom, Lagerstätte has yielded a diversity of remarkably preserved invertebrates, many of which provide fundamental insights into the evolutionary history and ecology of particular taxa. Here we report a new arthropod with 10 tiny arthropods tethered to its tergites by long individual threads. The head of the host, which is covered by a shield that projects anteriorly, bears a long stout uniramous antenna and a chelate limb followed by two biramous appendages. The trunk comprises 11 segments, all bearing limbs and covered by tergites with long slender lateral spines. A short telson bears long parallel cerci. Our phylogenetic analysis resolves the new arthropod as a stem-group mandibulate. The evidence suggests that the tethered individuals are juveniles and the association represents a complex brooding behavior. Alternative possibilities-that the tethered individuals represent a different epizoic or parasitic arthropod-appear less likely.arthropod | Silurian | brood care | juvenile | Herefordshire Lagerstätte

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Positional specification in the segmental growth pattern of an early arthropod

Cited by 25 publications

References 35 publications

The depositional environment and taphonomy of the Homerian “Aulacopleura shales” fossil assemblage near Loděnice, Czech Republic (Prague Basin, Perunican microcontinent)

The depositional environment and taphonomy of the Homerian “Aulacopleura shales” fossil assemblage near Loděnice, Czech Republic (Prague Basin, Perunican microcontinent)

Organogenesis in deep time: A problem in genomics, development, and paleontology

Tiny individuals attached to a new Silurian arthropod suggest a unique mode of brood care

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