A gravid fossil turtle from the Early Cretaceous reveals a different egg development strategy to that of extant marine turtles

Extant sea turtles develop and lay pliable (flexible) eggs; however, it is unknown whether they inherited this reproductive strategy from their closer fossil relatives or if it represents an evolutionary novelty. Here, we describe the first undisputable gravid marine fossil turtle ever found, from the early Cretaceous of Colombia, belonging to Desmatochelys padillai Cadena & Parham, which constitutes a representative of the Protostegidae. Using thin sectioning of one of the eggs, as well as scanning electron microscopy coupled with elemental characterization, cathodoluminescence, and computer tomography, we established that Desmatochelys padillai produced rigid eggs similar to those associated with some extant and fossil freshwater and terrestrial turtles. At least 48 spherical eggs were preserved inside this gravid turtle. We suggest that the development of rigid eggs in the extinct marine turtle Desmatochelys padillai resulted as an adaptation for egg‐embryo requirements dictated by the physical attributes of the nesting site.     

A new peculiar dinosaur egg,Sankofa pyrenaica oogen. nov. oosp. nov. from the Upper Cretaceous coastal deposits of the Aren Formation,south‐central Pyrenees,Lleida, Catalonia,Spain

Abstract: A new type of small, ovoid dinosaur egg, Sankofa pyrenaica oogen. nov. oosp. nov., with a prismatic type eggshell is described from upper Cretaceous (upper Campanian–Maastrichtian) deposits of the Montsec area, South Pyrenean Central Unit, Lleida, Catalonia, Spain. This egg type was sub‐vertically laid in only two rich monospecific sites of a single stratigraphic layer from coastal deposits of the Aren Formation, interpreted as an emerged beach ridge of a barrier island – lagoon depositional system. The size and shape of these eggs with their asymmetric poles are roughly similar to modern hen eggs, which is unusual in the Cretaceous fossil egg record. Its phylogenetic position clusters with bird and Troodontid eggs. A morphospace analysis of egg shapes shows the similarity of the new egg to a Campanian fossil bird egg from Argentina, both being intermediate between modern‐bird eggs and extinct nonavian theropod eggs. However, the eggshell microstructure of Sankofa pyrenaica differs from that of bird eggs in its incipient squamatic texture. It has a peculiar pattern of interlocking small crystals in the middle of the palisade layer, instead of the thick squamatic structure commonly present in modern avian eggshells. This new egg type is attributed to a small theropod, probably with a single oviduct like birds and whose mosaic distribution of features is a combination between that of birds and nonavian theropods. This enhances the arguments supporting the close phylogenetic relationships between both groups.     

Effects of intraclutch variation in egg size and hatching asynchrony on nestling development and survival in semi‐precocial Herring Gulls

Intraclutch egg size variation may non‐adaptively result from nutritional/energetic constraints acting on laying females or may reflect adaptive differential investment in offspring in relation to laying/hatching order. This variation may contribute to size hierarchies among siblings already established due to hatching asynchrony, and resultant competitive asymmetries often lead to starvation of the weakest nestling within a brood. The costs in terms of chick mortality can be high. However, the extent to which this mortality is egg size‐mediated remains unclear, especially in relation to hatching asynchrony which may operate concomitantly. I assessed effects of egg size and hatching asynchrony on nestling development and survival of Herring Gulls (Larus argentatus), where the smaller size and later hatching of c‐eggs may represent a brood‐reduction strategy. To analyze variation in egg size, I recorded the laying order and laying date of 870 eggs in 290 three‐egg clutches over a 3‐yr period (2010–2012). I measured hatchlings and monitored growth and survival of 130 chicks from enclosed nests in 2011 and 2012. The negative effect of laying date (β = ?0.18 ± SE 0.06, P = 0.002) on c‐egg size possibly reflected the fact that late breeders were either low quality or inexperienced females. The mass, size, and condition of hatchling Herring Gulls were positively related to egg size (all P < 0.0001). C‐chicks suffered from increased mortality risk during the first 12 d, identified as the brood‐reduction period in my study population. Although intraclutch variation in egg size was not directly related to patterns of chick mortality, I found that smaller relative egg size interactively increased differences in relative body condition of nestlings, primarily brought about by the degree of hatching asynchrony during this brood‐reduction period. Thus, the value of relatively small c‐eggs in Herring Gulls may lie in reinforcing brood reduction through effects on nestling body condition. A reproductive strategy Herring Gulls might have adopted to maintain a three‐egg clutch, but that also enables them to adjust the number of chicks they rear relative to the prevailing environmental conditions and to their own condition during the nestling stage.     

Attractive blue‐green egg coloration and cuckoo−host coevolution

Recent evidence suggests that blue‐green coloration of bird eggshells may be related to female and/or egg phenotypic quality, and that such colour may affect parental effort and therefore the nutritional environment of developing nestlings. Here we suggest that these relationships and the signal function of eggshell coloration would affect the outcome of coevolution between avian brood parasites and their hosts in at least three different non‐exclusive evolutionary pathways. First, by laying blue‐green coloured eggs, cuckoo females may exploit possible sensory biases of their hosts, constraining the evolution of parasitic egg recognition, and thus avoid rejection. Second, because of the relatively high costs of laying blue eggs, cuckoo females may be limited in their ability to mimic costly blue‐green eggs of their hosts because cuckoo females lay many more eggs than their hosts. Furthermore, costs associated with foreign egg recognition errors would be relatively higher for hosts laying blue eggs. Third, cuckoos may use coloration of host eggs for selecting individuals or specific hosts of appropriate phenotypic quality (i.e. parental abilities). We here explored some predictions emerging from the above scenarios and found partial support for two of them by studying egg coloration of European cuckoos (Cuculus canorus) and that of their 25 main hosts, as well as parasitism and rejection rate of hosts. Cuckoo hosts parasitized with more blue, green, and ultraviolet cuckoo eggs, or those laying more blue‐green eggs, were more prone to accept experimental parasitism with artificial cuckoo eggs. In addition, coloration of cuckoo eggs is more variable when parasitizing hosts laying bluer‐greener eggs, even after controlling for the effect of host egg coloration (i.e. degree of egg matching). Globally, our results are consistent with the proposed hypothesis that host egg traits that are related to phenotypic quality of hosts, such as egg coloration, may have important implications for the coevolutionary interaction between hosts and brood parasites. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 154–168.     

Wing morphology of a new Cretaceous praying mantis solves the phylogenetic jigsaw of early‐diverging extant lineages

The extremely derived morphology and behaviour of extant praying mantises combined with a scarce record of fossil relatives introduce significant challenges to tracing their evolution from Palaeozoic stem‐dictyopterans. Extant members of Chaeteessidae, Mantoididae and Metallyticidae could be invaluable to resolving the mantodean tree, yet their inclusion in phylogenetic analyses led to conflicting hypotheses due to their highly disparate respective morphologies. In this contribution, we present Labradormantis guilbaulti gen. et sp.n. , a new fossil species described from both fore‐ and hind‐wing imprints discovered in the Redmond Mine locality (Late Cretaceous, Cenomanian, Redmond Formation; Labrador, Canada). The examination of its hind‐wing AA2* supports the hypothesis that this structure, unique to Chaeteessidae among extant mantises, is a true vein and that its occurrence represents a plesiomorphy for Mantodea. A parsimony analysis including newly coded wing‐related characters further established that L. guilbaulti gen. et sp.n. displays a unique combination of plesiomorphic and apomorphic character states that situates it within the extinct family Baissomantidae. This dataset resolved the phylogenetic relationships of early‐diverging extant lineages as (Chaeteessidae (Mantoididae (Metallyticidae, Artimantodea))), and suggested that the Eocene Lithophotina floccosa Cockerell might be a close relative of extant metallyticids. It also indicated a trend towards increased modularity within mantis fore‐wings, in contrast with a trend towards increased morphological integration in their hind‐wings, both of which are potentially associated with improved flight performance for modern mantises. This study emphasizes the importance of fossils for resolving phylogenetic relationships and for introducing transitional phenotypes to infer ancient evolutionary trends of extant derived clades.     

Report of a cohesive gelatinous egg mass produced by a tropical marine bivalve

Abstract. Gelatinous egg masses are common in a number of animal phyla. However, they are virtually unknown in marine bivalves, with structures that could be thought of as gelatinous egg masses being reported for only five species. We describe the gelatinous egg mass and intracapsular development in the tropical lucinid Phacoides pectinatus. The embryos developed within individual capsules embedded in a large flimsy, spherical mass. Swimming veligers hatch at 198 μm shell length. They did not feed, settled within several days of hatching, and metamorphosis was completed within 2 weeks of hatching. Gelatinous egg masses might be detected in members of more lucinid species if studies of development included field or in vivo observations of reproduction in addition to producing embryos by stripping the gonads.     

The anatomy of the upper cretaceous snake Najash rionegrina Apesteguía & Zaher, 2006, and the evolution of limblessness in snakes

Najash rionegrina Apesteguía & Zaher, 2006 , a terrestrial fossil snake from the Upper Cretaceous of Argentina, represents the first known snake with a sacrum associated with robust, well‐developed hind limbs. Najash rionegrina documents an important gap in the evolutionary development towards limblessness, because its phylogenetic affinities suggest that it is the sister group of all modern snakes, including the limbed Tethyan snakes Pachyrhachis, Haasiophis, and Eupodophis. The latter three limbed marine fossil snakes are shown to be more derived morphologically, because they lack a sacrum, but have articulated lymphapophyses, and their appendicular skeleton is enclosed by the rib cage, as in modern snakes.     

A well‐preserved ‘charadriiform‐like’ fossil bird from the Early Eocene Fur Formation of Denmark

Abstract: We describe a new, exceptionally well‐preserved fossil bird recovered from marine deposits of the Early Eocene Fur Formation of Denmark. Morsoravis sedilis gen. et sp. nov. is known by a single specimen that consists of a three‐dimensional skull, vertebral column, ribs, pelvis, and left hindlimb and associated parts of the right hindlimb. Comparisons based on overall morphology and particularly characters of the skull, vertebrae and pelvis indicate that the new specimen is morphologically similar to charadriiform birds (the shorebirds and relatives). This similarity is also expressed by a phylogenetic analysis of higher neornithine (modern birds) taxa, which supports a close relationship between the new fossil and modern charadriiforms. The morphology of the hindlimbs, in particular, shows that the new fossil corresponds to a new taxon that is distinguishable from modern charadriiform clades. One interesting aspect of its morphology is the presence of hindlimb specializations that are most commonly found among perching birds – these suggest that ecologically the new Danish fossil bird may have differed from the wading habits typical of most charadriiforms.     

Effects of embryonic responses to clutch mates on egg hatching patterns of Pentatomidae (Heteroptera)

Stink bugs and shield bugs of the family Pentatomidae (Heteroptera) generally produce a clutch of densely deposited eggs. In a few species of this family, embryos hatch in response to some form of cues associated with the preceding hatching to synchronize egg hatching with clutch mates. The aim of the present study is to obtain a family‐wide understanding of the extent to which the hatching response to clutch mates accelerates hatching within egg clutches. Accordingly, the hatching patterns in intact egg clutches and eggs individually detached from egg clutches are compared in eight species among different genera. In Halyomorpha halys, hatching is significantly and highly synchronized by the effect of the hatching response: when eggs are not attached to each other, the hatching rate is only 3.8% at 15 min and exceeds 95% at 200 min. By contrast, when eggs are attached to each other, the hatching rate reaches more than 95% at 15 min. Hatching is also significantly synchronized by the hatching response in Nezara viridula (which shows relatively high hatching synchronization) and in Piezodorus hybneri and Plautia stali (both of which show milder hatching synchronization). Synchronization of hatching is not found to be promoted by a hatching response in Aelia fieberi, Dolycoris baccarum, Eurydema rugosum or Palomena angulosa. These findings reveal that the hatching response varies depending on the species in Pentatomidae, with a wide spectrum of effects on the hatching patterns of the egg clutches.     

Non‐actualistic wood‐fall associations from Middle Jurassic of Poland

Kaim, A. 2010: Non‐actualistic wood‐fall associations from Middle Jurassic of Poland. Lethaia, Vol. 44, pp. 109–124. The oldest modern‐type wood‐fall (sunken wood) associations so far known, were reported from the Upper Cretaceous of Japan. Here, four Middle Jurassic fossil associations collected from logs of sunken driftwood are documented from clay and silt sediments of the Cz?stochowa Ore‐bearing Clay Formation in Poland. The associations are composed of almost entirely different set of molluscs when compared to modern examples of wood‐fall communities. The exceptions are leptochitonid polyplacophorans and alleged cocculinoid gastropods, both of which are typical of modern sunken wood communities. It is hypothesized here that the associations represent Jurassic wood‐fall communities, which in contrast to their modern counterparts do not contain associated chemosymbiotic animals. This disparity results from the absence of xylophagain wood‐boring bivalves, which since the Cretaceous have produced significant amounts of faecal pellets, the decomposition of which increases the amount of sulphide around sunken driftwoods. The associations are considered as benthic rather than pseudoplanktonic because the wood logs were colonized only on their upper side, the abundant crinoids belong to benthic genera rather than to pseudoplanktonic, associations include numerous infaunal organisms, and there are too many clingers in the associations. The most typical and numerous members of the investigated associations are the gastropods Cosmocerithium and Astandes, both having uncertain taxonomic positions. It is suggested here that Cosmocerithium could be a grazer of bacterial mats, and represents an ecological counterpart of modern Provannidae. □chitons, cocculinoids, deep sea, ecology, evolution, Wood‐fall communities.     

Early evolution of Nemopteridae illuminated with the first and oldest thread‐winged lacewing in Cretaceous amber

Nemopteridae are a charismatic family of lacewings distinguished by specialization of morphology in both larvae and adults as well as in their biology and behaviour. The evolutionary history of Nemopteridae is largely unknown due to the scarcity of fossil records. Here we report a new genus and species of Nemopteridae (Cretocroce xiai gen. et sp.n.) based on an exquisitely preserved adult specimen in mid‐Cretaceous Burmese amber. We place the new genus in the subfamily Crocinae, which is characterized by filamentous hindwings with a sensory function as an adaptation to their cavernicolous habitats. The new genus represents the first nemopterid in amber and the oldest crocine known to date. The new fossil crocine is nearly morphologically unchanged over 99 Ma compared with its modern counterparts. Moreover, it is estimated to be closely related to some extant crocines endemic to South America based on morphological phylogenetic analysis. The new finding provides direct evidence to demonstrate the antiquity of Crocinae morphological innovation and related biology, such as pollenophagous habits, and further corroborates Gondwanan origin of the subfamily. The published work has been registered on ZooBank: http://zoobank.org/urn:lsid:zoobank.org:pub:3D29DE48‐DBD8‐4614‐8387‐D9FCF90B0640 .     

Reidentification of Avian Embryonic Remains from the Cretaceous of Mongolia

Embryonic remains within a small (4.75 by 2.23 cm) egg from the Late Cretaceous, Mongolia are here re-described. High-resolution X-ray computed tomography (HRCT) was used to digitally prepare and describe the enclosed embryonic bones. The egg, IGM (Mongolian Institute for Geology, Ulaanbaatar) 100/2010, with a three-part shell microstructure, was originally assigned to Neoceratopsia implying extensive homoplasy among eggshell characters across Dinosauria. Re-examination finds the forelimb significantly longer than the hindlimbs, proportions suggesting an avian identification. Additional, postcranial apomorphies (strut-like coracoid, cranially located humeral condyles, olecranon fossa, slender radius relative to the ulna, trochanteric crest on the femur, and ulna longer than the humerus) identify the embryo as avian. Presence of a dorsal coracoid fossa and a craniocaudally compressed distal humerus with a strongly angled distal margin support a diagnosis of IGM 100/2010 as an enantiornithine. Re-identification eliminates the implied homoplasy of this tri-laminate eggshell structure, and instead associates enantiornithine birds with eggshell microstructure composed of a mammillary, squamatic, and external zones. Posture of the embryo follows that of other theropods with fore- and hindlimbs folded parallel to the vertebral column and the elbow pointing caudally just dorsal to the knees. The size of the egg and embryo of IGM 100/2010 is similar to the two other Mongolian enantiornithine eggs. Well-ossified skeletons, as in this specimen, characterize all known enantiornithine embryos suggesting precocial hatchlings, comparing closely to late stage embryos of modern precocial birds that are both flight- and run-capable upon hatching. Extensive ossification in enantiornithine embryos may contribute to their relatively abundant representation in the fossil record. Neoceratopsian eggs remain unrecognized in the fossil record.     

Phylogeny of split‐footed lacewings (Neuroptera,Nymphidae), with descriptions of new Cretaceous fossil species from China

A phylogeny of the lacewing family Nymphidae based on morphology and DNA sequences is presented including representatives of all living genera and selected fossil genera. Widely distributed Jurassic and Cretaceous genera gave rise to recent taxa now restricted to Australasia. Two previously defined clades (i.e. Nymphinae and Myiodactylinae) were recovered and reflect the diverging adult and larval morphology of members of these two subfamilies. From Chinese Cretaceous deposits, a new genus (Spilonymphes gen. nov.) is described with one new species, as well as new species described in the genera Baissoleon Makarkin and Sialium Westwood.     

Combining geometric morphometrics,molecular phylogeny,and micropaleontology to assess evolutionary patterns in Mallomonas (Synurophyceae: Heterokontophyta)

Synurophytes, also known as scaled chrysophytes, are ecologically important algae that produce an array of siliceous structures upon which their taxonomy is based. Despite occupying a key position within the photosynthetic heterokonts, the evolutionary history of synurophytes remains poorly constrained. Here, modern and Middle Eocene siliceous scales of the morphotaxon Mallomonas insignis are used as a model to investigate synurophyte evolutionary patterns. Structural details of scale morphology were examined comparatively with scanning electron microscopy and scored for geometric morphometric analyses to assess the stability of shape characters. Although consistent size differences exist (modern scales are larger than Eocene counterparts), the populations cannot be differentiated on the basis of shape or microstructural detail, implying considerable evolutionary stasis in scale morphology. A time‐calibrated relaxed molecular clock analysis using a three‐gene concatenated data set (27 strains) suggests that the M. insignis lineage predates the available fossil record, having diverged from closest congeneric taxa in the Cretaceous (≥94 Ma). However, the molecular analysis also implies that considerable genetic variability is present within several morphotaxa of Mallomonas, implying that substantial genetic variability has arisen despite the retention of uniform scale morphologies, and resulting in the widespread occurrence of cryptic taxa. Results from the synurophyte lineage are consistent with the notion of protracted ghost ranges (>10 Ma) implied by the molecular phylogenies of other algal groups, together pointing to the paucity of the fossil record of these organisms on these timescales.     

Yellow mutant of the Neotropical green lacewing Chrysoperla externa: trait inheritance and predator performance

The Neotropical green lacewing Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) is a key predator of various small soft‐bodied pest species. Chrysopidae species are known as ‘green lacewings’ due to their overall green body coloration. However, yellow mutant individuals were observed emerging from our lacewing rearing colony. Thus, the mode of inheritance of the yellow trait was studied and the hypothesis of an autosomal recessive allele for yellow color was tested using hybridization and backcrossing techniques. Furthermore, the possible implications of this color variation on specific life‐history characteristics of C. externa and the predation rates of each morph were evaluated. In both yellow and green morphs, basic life‐history characteristics were monitored, including time to hatching and viability of eggs, duration, and viability of larval and pupal stages, emergence rate and survivorship of adults, and fecundity and longevity of females. The yellow and green morphs were indistinguishable with respect to all life‐history traits evaluated and the predation rate of their larvae. Crossing experiments revealed the yellow color to be caused by a homozygous recessive allele, without sex‐linked expression. We conclude that the allele for yellow color is occurring at high frequency in the laboratory colony, supporting the existence of a genetic polymorphism for body ground color.     

Acute toxic effects of 8‐epidiosbulbin E,a 19‐norclerodane diterpene from yam Dioscorea antaly,on medaka Oryzias latipes embryos

The fractionation of an aqueous extract of yam Dioscorea antaly from Madagascar led to the isolation of terpenoids and flavonoids. Compounds were identified on the basis of modern mass spectrometry and two‐dimensional nuclear magnetic resonance (2D‐NMR). Toxicological effects of the most abundant isolated compound, 8‐epidiosbulbin E were studied on medaka Oryzias latipes embryo‐larval development. The lethal concentration (killing 50%; LC₅₀) to embryos treated 24 h before hatching and for 3 days after hatching was estimated to be 0·56 mg ml^?1 (P< 0·05). No mortality was observed with O. latipes larvae exposed after hatching until day 4. Anatomo‐pathological studies of embryos exposed to 0·56 mg ml^?1 showed development anomalies of the central nervous system, liver, muscle and intestine. The present data thus extend the model of O. latipes embryos as a useful animal model to analyse the effects of food toxins.     

Reassessing the endemic European Upper Cretaceous dinosaur egg Cairanoolithus

The fossil record of dinosaur eggs and eggshells from the uppermost Cretaceous strata of south-western Europe is composed of both worldwide-distributed and endemic egg types. In this study, we are reviewing the enigmatic European oogenus Cairanoolithus, which after analysing abundant material from classic and new localities it is reassigned to a new oofamily (Cairanoolithidae oofam. nov.) in the light of the unique combination of structural characters. The new oofamily includes one oogenus and two oospecies. Cairanoolithid eggs share several features with other ornithopod egg types indeed. Furthermore, our phylogenetic analysis places Cairanoolithus as the sister ootaxon of the ornithopod ootaxa, being considered the most basal ornithischian egg type known so far. Although neither embryonic nor bones remains are known in association with cairanoolithid eggs so far, several taxonomic attributions have been proposed for this egg type over time. On the basis of microstructural features, phylogenetic results and anatomical constrains, we discuss in this paper previous taxonomic attributions and provide new evidence for suggesting a plausible nodosaurid affinity.     

Lesser double‐collared sunbirds Nectarinia chalybea do not compensate for hatching asynchrony by adjusting egg mass or yolk androgens

Substantial amounts of maternal androgens are found in birds’ eggs and have been shown to benefit offspring development. Within‐clutch patterns of increasing androgen concentrations over the laying sequence are often hypothesized to compensate for the negative effects of hatching asynchrony. However, detrimental effects to offspring fitness of exposure to high yolk androgen levels have also been demonstrated. This suggests that mothers should forego these costs to their offspring when the need for compensation for hatching asynchrony is low or when alternative compensatory strategies, e.g. in terms of increasing egg mass, are available. Here we show that in the south‐temperate lesser double‐collared sunbird Nectarinia chalybea, a species with hatching asynchrony but also with high survival of last‐hatched chicks, mothers do not deposit resources differentially in terms of either yolk androgen concentration or egg mass across the laying sequence. We discuss to what extend this challenges the original explanation of within‐clutch variation in these egg parameters and offer some explanation for their between‐clutch variation which was related to female body mass.     

Crocodylomorph eggs and eggshells from the Adamantina Formation (Bauru Group), Upper Cretaceous of Brazil

Abstract: Compared with crocodylomorph body fossils, the record of fossil crocodiloid eggs is scarce and poorly understood, a gap partially attributed to their typically thin eggshell, which is not conducive to preservation. A remarkable new association of well‐preserved eggs and eggshells from the Adamantina Formation (Bauru Group, Upper Cretaceous) is described and compared to other known materials, while the significance of their unique oological features is discussed. These eggs constitute a new ootaxon, Bauruoolithus fragilis oogen. et oosp. nov., diagnosed by the following characteristics: elongate and elliptical egg with blunt ends; length‐to‐diameter ratio of 1:0.55; outer surface slightly undulating; shell thickness ranging from 0.15 to 0.25 mm; pore openings elliptical or teardrop‐shaped, ranging from 30 to 80 μm in diameter; and shell units wider than higher, with the interstices forming an obtuse triangle. Specimens of Bauruoolithus also show only slight signs of extrinsic degradation that, coupled with the evidence that some of them constitute hatched eggs, suggests that the egg‐laying taxon had a different pattern of egg incubation, in which the hatchling could break through the rather thin eggshell relatively easily and that the extrinsic degradation of the eggshell was not necessary. This contrasts with the pattern of incubation for all other known crocodylomorphs and crocodiloid eggs, where extrinsic degradation is a key component of the hatching process.