A three-dimensionally preserved 2-mm-long larva of the arthropod Leanchoilia illecebrosa from the 520-million-year-old early Cambrian Chengjiang biota of China represents the first evidence, to our knowledge, of such an early developmental stage in a shortgreat-appendage (SGA) arthropod. The larva possesses a pair of three-fingered great appendages, a hypostome, and four pairs of well-developed biramous appendages. More posteriorly, a series of rudimentary limb Anlagen revealed by X-ray microcomputed tomography shows a gradient of decreasing differentiation toward the rear. This, and postembryonic segment addition at the putative growth zone, are features of late-stage metanauplii of eucrustaceans. L. illecebrosa and other SGA arthropods, however, are considered representative of early chelicerates or part of the stem lineage of all euarthropods. The larva of an early Cambrian SGA arthropod with a small number of anterior segments and their respective appendages suggests that posthatching segment addition occurred in the ancestor of Euarthropoda.Cambrian radiation | 3D preservation | micro-CT | arthropod larva | Chengjiang biota

Mantodeans or praying mantises are flying insects and well known for their raptorial behaviour, mainly performed by their first pair of thoracic appendages. We describe here a new, exceptionally preserved specimen of the early mantodean Santanmantis axelrodi Grimaldi, 2003 from the famous 110 million years old Crato Formation, Brazil. The incomplete specimen preserves important morphological details, which were not known in this specific form before for this species or any other representative of Mantodea. Unlike in modern representatives or other fossil forms of Mantodea not only the first pair of thoracic appendages shows adaptations for predation. The femora of the second pair of thoracic appendages bear numerous strong, erect spines which appear to have a sharp tip, with this strongly resembling the spines of the first pair of thoracic appendages. This indicates that individuals of S. axelrodi likely used at least two pairs of thoracic appendages to catch prey. This demonstrates that the prey-catching behaviour was more diverse in early forms of praying mantises than anticipated.

Insects use different parts of their body to cling to mating partners, to catch prey, or to defend themselves, in most cases the mouthparts or the legs. However, in 400 million years of evolution [1, 2], specialized devices were independently acquired in several groups to adopt these tasks, as for instance modified legs in mantids, assassin bugs or stick insects [3-5], or clasping antennae of the globular springtails [6]. So far, no known species used the neck region between the head and thorax in one of these functional contexts. Here we describe females of †Caputoraptor elegans, a very unusual, presumably predacious insect discovered in approximately 100-million-year-old [7] Burmese amber. Based on several morphological features, we conclude that this species lived in the foliage of trees or bushes. A unique feature of the new taxon is a scissor-like mechanism formed by wing-like extensions on the posterior head and corresponding serrated edges of the dorsal sclerite of the first thoracic segment. Based on the specific structure of the apparatus, we conclude that it was probably used by females to hold on to males during copulation. A defensive or prey-catching function appears less likely. A similar mechanism did not evolve in any other known known group of extant or extinct insects.

Diatoms are encased within sophisticated stable lightweight silica cell walls. These frustules have the potential to protect the algal cell against the feeding tools of their most abundant metazoan predators, the copepods. We examined the mechanical strengths of the 3 North Sea diatom species Actinoptychus senarius, Thalassiosira punctigera and Coscinodiscus wailesii and their effect on feeding efficiency of copepods. (1) We determined the stability of the diatoms by means of 'micro-crush-tests' performed in the laboratory with calibrated microneedles. (2) In feeding experiments, we compared the ability and efficiency of the 3 North Sea copepod species Temora longicornis, Centropages hamatus and Acartia clausi to crush frustules. The results showed a remarkable correlation between mechanical properties and size of diatom frustules and feeding success of the copepods. The weakly silicified diatom T. punctigera was the least stable and best fed upon, whilst having the highest growth rate. The diatoms having the most complex frustule, A. senarius, exhibited the greatest stability, whilst being fed upon least. The largest diatom, C. wailesii, was partially protected by its size, but was nonetheless suitable as prey for the large copepods that, in the case of C. hamatus, seem to have developed special feeding techniques to overcome the size-mediated protection.

Joachim T. 2016. What nymphal morphology can tell us about parental investment-a group of cockroach hatchlings in Baltic amber documented by a multi-method approach.