The L1-type transmembrane protein Echinoid [1] is essential for the proper spatial patterning of the compound eye in the fruitfly Drosophila. Two recent papers [2,3] report that, in echinoid mutant flies, the primary defect is in patterning a specific cell type, the R8 photoreceptor cell. During normal eye development in Drosophila, a single R8 cell founds each ommatidium, but in echinoid mutan...

Precisely regulated Egfr activity is essential for normal development and cell differentiation. We demonstrate that the transmembrane protein Echinoid is required to downregulate Egfr activity in the developing Drosophila eye, ensuring a normal array of R8 photoreceptor neurons. Echinoid is an L1-type transmembrane molecule that is expressed in all cells of the eye imaginal discs and, unlike ma...

The Notch intercellular signalling pathway is important throughout development, and its components are modulated by a variety of cellular and molecular mechanisms. Ligand and receptor trafficking are tightly controlled, although context-specific regulation of this is incompletely understood. We show that during sense organ precursor specification in Drosophila, the cell adhesion molecule Echino...

Specification of the germ cell lineage is required for sexual reproduction in all animals. However, the timing and mechanisms of germ cell specification is remarkably diverse in animal development. Echinoderms, such as sea urchins and sea stars, are excellent model systems to study the molecular and cellular mechanisms that contribute to germ cell specification. In several echinoderm embryos te...

The Permian-Triassic bottleneck has long been thought to have drastically altered the course of echinoid evolution, with the extinction of the entire echinoid stem group having taken place during the end-Permian mass extinction. The Early Triassic fossil record of echinoids is, however, sparse, and new fossils are paving the way for a revised interpretation of the evolutionary history of echino...

Two new echinoid genera and species, Salvaster roberti gen. et sp. nov. and Pygolampas edita gen. et sp. nov. are described. They were collected in the Calcaires à Spatangues Formation (CSF) that consists of limestone and clay sediments deposited in the southeast of the Paris Basin (France) during the Early Hauterivian (Early Cretaceous). The CSF is dated from the Acanthodiscus radiatus chronoz...

EGF receptor signalling plays diverse inductive roles during development. To achieve this, its activity must be carefully regulated in a variety of ways to control the time, pattern, intensity and duration of signalling. We show that the cell surface protein Echinoid is required to moderate Egfr signalling during R8 photoreceptor selection by the proneural gene atonal during Drosophila eye deve...

This dataset inventories occurrence records of fossil echinoid specimens collected in the Calcaires à Spatangues Formation (CSF) that crops out in the southeast of the Paris Basin (France), and is dated from the Acanthodiscus radiatus chronozone (ca. 132 Ma, early Hauterivian, Early Cretaceous). Fossil richness and abundance of the CSF has attracted the attention of palaeontologists since the m...

In the present study, Kabir kuh Section, related to the Seymareh or Lopha Limestone member (Gurpi Formation) have been Selected. The member has yielded a rich echinoid fauna and 21 species of Echinoid belonging to 14 genera are recognized and described. The Kabir Kuh section yielded two regular echinoid taxa: Salenia nutrix and Goniopygus superbus, one holectypoid taxa: Coptodiscus noemiae, two...

Echinoids, or sea urchins, are rare in the Palaeozoic fossil record, and thus the details regarding the early diversification of crown group echinoids are unclear. Here we report on the earliest probable crown group echinoid from the fossil record, recovered from Permian (Roadian-Capitanian) rocks of west Texas, which has important implications for the timing of the divergence of crown group ec...