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Ecatepec, Mexico

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Ecatepec, Mexico
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Ortega-Hernandez J.,University of Cambridge | Lerosey-Aubril R.,University Claude Bernard Lyon 1 | Kier C.,Back to the Past Museum | Bonino E.,Back to the Past Museum
Palaeontology | Year: 2015

We describe a weakly biomineralized non-trilobite artiopodan arthropod from the Guzhangian Weeks Formation of Utah. Falcatamacaris bellua gen. et sp. nov. is typified by a thin calcitic cuticle, broad cephalon without eyes or dorsal ecdysial sutures, an elongate trunk with distinctively sickle-shaped pleural spines and a long tailspine with a bifurcate termination. The precise affinities of Falcatamacaris gen. nov. are problematic due to the presence of unique features within Artiopoda, such as the peculiar morphology of the pleural and posterior regions of the trunk. Possible affinities with aglaspidid-like arthropods and concilitergans are discussed based on the possession of 11 trunk tergites, edge-to-edge articulations and overall body spinosity. The new taxon highlights the importance of the Weeks Formation Konservat-Lagerstätte for further understanding the diversity of extinct arthropod groups in the upper Cambrian. © The Palaeontological Association.

Lerosey-Aubril R.,University Claude Bernard Lyon 1 | Ortega-Hernandez J.,University of Cambridge | Kier C.,Back to the Past Museum | Bonino E.,Back to the Past Museum
Geological Magazine | Year: 2013

The Guzhangian Weeks Formation preserves a diverse, yet virtually unstudied, non-trilobite arthropod fauna. Here we describe Tremaglaspis vanroyi sp. nov., the oldest representative of an enigmatic group of extinct arthropods, the Aglaspidida. Tremaglaspis was previously known from the Lower Ordovician and its morphology was regarded as particularly derived within the clade. Its occurrence in the Cambrian of Utah suggests that much of the early evolutionary history of the Aglaspidida remains unknown. A review of the environmental settings of previous aglaspidid findings suggests that these arthropods preferentially inhabited shallow-water environments, which may partially explain their limited fossil record. Copyright © Cambridge University Press 2013.

Lerosey-Aubril R.,Senckenberg Institute | Hegna T.A.,Yale University | Hegna T.A.,Western Illinois University | Kier C.,Back to the Past Museum | And 3 more authors.
PLoS ONE | Year: 2012

Despite being internal organs, digestive structures are frequently preserved in Cambrian Lagerstätten. However, the reasons for their fossilisation and their biological implications remain to be thoroughly explored. This is particularly true with arthropods - typically the most diverse fossilised organisms in Cambrian ecosystems - where digestive structures represent an as-yet underexploited alternative to appendage morphology for inferences on their biology. Here we describe the phosphatised digestive structures of three trilobite species from the Cambrian Weeks Formation Lagerstätte (Utah). Their exquisite, three-dimensional preservation reveals unique details on trilobite internal anatomy, such as the position of the mouth and the absence of a differentiated crop. In addition, the presence of paired pygidial organs of an unknown function is reported for the first time. This exceptional material enables exploration of the relationships between gut phosphatisation and the biology of organisms. Indeed, soft-tissue preservation is unusual in these fossils as it is restricted to the digestive structures, which indicates that the gut played a central role in its own phosphatisation. We hypothesize that the gut provided a microenvironment where special conditions could develop and harboured a source of phosphorus. The fact that gut phosphatization has almost exclusively been observed in arthropods could be explained by their uncommon ability to store ions (including phosphorous) in their digestive tissues. However, in some specimens from the Weeks Formation, the phosphatisation extends to the entire digestive system, suggesting that trilobites might have had some biological particularities not observed in modern arthropods. We speculate that one of them might have been an increased capacity for ion storage in the gut tissues, related to the moulting of their heavily-mineralised carapace. © 2012 Lerosey-Aubril et al.

Lerosey-Aubril R.,CNRS Geological Laboratory of Lyon: earth, planets and environment | Hegna T.A.,Western Illinois University | Babcock L.E.,Ohio State University | Babcock L.E.,Lund University | And 2 more authors.
Bulletin of Geosciences | Year: 2014

The Guzhangian Weeks Formation (House Range, Utah, USA) contains a virtually unstudied but diverse assemblage of "soft-bodied" organisms. This fauna includes several enigmatic appendages of arthropods that are described in this contribution. Six appendages (two isolated and four paired appendages) are interpreted as frontal appendages of a probably new species of Anomalocaris. They are characterized by a slender morphology, 14 podomeres, ventral spines alternating in size, up to three auxiliary spines per ventral spine, and only two dorsal spines. Another isolated appendage is also tentatively assigned to Anomalocaris, but it exhibits a more robust morphology, a stronger distal tapering, and apparently simple ventral spines, suggesting that it may represent a distinct taxon. These frontal appendages represent the youngest occurrence of anomalocaridids in Laurentia and demonstrate the persistence of older, Burgess Shale-type taxa in the Weeks Formation. An assemblage of four antenniform and six robust and heavily-armed appendages is also described. These are interpreted as the serially arranged, anterior appendages of a single individual of an undetermined arthropod species. This association of three pairs of robust, spiny appendages with two pairs of antenniform structures in a Cambrian arthropod is unique.

Here we describe a new species of the subgenus Acanthopyge (Belenopyge) from Morocco and we also mention all the species belonging to the same subgenus. Specifically, Acanthopyge (Belenopyge) estevei sp. nov. from the Ihandar Formation, Lower Devonian (Pragian) of El Achana, Mader region; A. (Belenopyge) basssei Chatterton & Gibb, 2010 from the El Otfal Formation, Middle Devonian (Eifelian) of Jbel Issoumour; two specimens of A. (Belenopyge) estevei sp. nov. from the Ihandar Formation, Lower Devonian (Pragian) of Jbel Oufatene and Jbel El Mrakib; and finally another species (that we leave under open nomenclature) form the Mdâouer el Kbîr Formation, Lower Devonian (Pragian) of Mdaouer el Kbir. All these outcrops are located in the Anti-Atlas region (southeast of Morocco).

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