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Despite the status of the eye as an 'organ of extreme perfection' (1), theory suggests that complex eyes can evolve very rapidly (2). The fossil record has, until now, been inadequate in providing insight into the early evolution of eyes during the initial radiation of many animal groups known as the Cambrian explosion. This is surprising because Cambrian Burgess-Shale-type deposits are replete with exquisitely preserved animals, especially arthropods, that possess eyes (3-5). However, with the exception of biomineralized trilobite eyes, virtually nothing is known about the details of their optical design. Here we report exceptionally preserved fossil eyes from the Early Cambrian (~515 million years ago) Emu Bay Shale of South Australia, revealing that some of the earliest arthropods possessed highly advanced compound eyes, each with over 3,000 large ommatidial lenses and a specialized 'bright zone'. These are the oldest nonbiomineralized eyes known in such detail, with preservation quality exceeding that found in the Burgess Shale and Chengjiang deposits. Non-biomineralized eyes of similar complexity are otherwise unknown until about 85 million years later (6,7). The arrangement and size of the lenses indicate that these eyes belonged to an active predator that was capable of seeing in low light. The eyes are more complex than those known from contemporaneous trilobites and are as advanced as those of many living forms. They provide further evidence that the Cambrian explosion involved rapid innovation in fine-scale anatomy as well as gross morphology, and are consistent with the concept that the development of advanced vision helped to drive this great evolutionary event (8)., The anatomy of many Early and Middle Cambrian (-520-500 million years (Myr) ago) organisms is known in considerable detail from numerous Burgess-Shale-type deposits worldwide (3-5), but the fine structure of [...]

New and previously described 'Sphinctozoan' taxa have been collected from six different localities in northern Spain, all of them dated as Late Carboniferous, from Moskovian to Kasimovian in age. The sphinctozoans in the collection are all assigned to the Demospongiae: a new species of polyglomerate type, Cystothalamia vandegraaffi n. sp., and known species Amblysiphonella barroisi Steinmann, 1882, Arnblysiphonella carbonaria (Steinmann, 1882), Discosiphonella mammilosa (King, 1943), Discosiphonella major (Van de Graaff, 1969), and Sollasia ostiolata Steinmann, 1882. Some of these specimens present interesting paleoecological features, such as the use of a piece of calcareous algae as a hard substrate in a soft muddy bottom and a possible branching pattern determined by photophilic or negative geotaxic growth.

New collections of fossil sponges have been recovered from Devonian to Upper Carboniferous sections of Spain. These include two new hexactinellids from Devonian rocks of northwestern Spain: the small globular protospongiid Iberospongia globulara new genus and species, and the much larger, bowl-shaped, pelicaspongiid Asturiaspongia aqualiforma new genus and species. The three specimens of Asturiaspongia n. gen. were collected from the calcareous member of the Aguion Formation, of late Emsian age, at Arnao Beach, Asturias. This member has been interpreted as a developing patch reef. The single specimen of Iberospongia n. gen. was collected from late Zlichovian (Emsian) beds of the Cortes Member of the Abadia Formation, near Polentinos, Palencia. These beds represent the beginning of the transition to deeper water that took place during the Emsian and which lasted throughout the Devonian. Lower Carboniferous sponges have been collected from southern Spain. The hexactinellid Estrellaspongia irregulara new genus and species, is a thick-walled, basin-shaped pelicaspongiid with irregular, branched, inhalant canals and coarser irregular canals in a skeleton of irregularly oriented and spaced small hexactines. It is from late Visean rocks of Sierra de la Estrella, near Espiel in Cordoba. The reticulosid Stereodictyum orthoplectum Finks, 1960 was collected from Visean beds at Las Pilitas 2, Badajoz. It has a body wall of alternating layers of regularly spaced vertical and horizontal bundles of spicules in the quadrate-appearing skeleton. This is the first report of the genus from Europe and it is the oldest known occurrence of the genus. Upper Carboniferous sponges, Bashkirian to Moscovian-Kasimovian, have been collected from northern Spain. Demosponges include: Heliospongia excavata King, 1933; Coelocladia spinosa Girty, 1908; small generically unidentifiable anthaspidellids; Haplistion Girty, 1908 sp. 1 and sp. 2; and a small fragmentary monaxonid demosponge of uncertain taxonomic assignment. Hexactinellida include the reticulosids, Stioderma perforata new species, and Stioderma Finks, 1960 sp. A, and the new amphidiscosids, Ascospongiella capdevilae new genus and species and Hadrophragmos soleniscus new genus and species. Root tufts A, B, and C are of uncertain taxonomic assignment.

Author(s): Diego C. García-Bellido [1, 2]; Desmond H. Collins (corresponding author) [1] Until now, the existence of ecdysis (moulting) in early arthropods has been based solely on inference. Here we [...]