Discriminating signal from noise in the fossil record of early vertebrates reveals cryptic evolutionary history

The fossil record of early vertebrates has been influential in elucidating the evolutionary assembly of the gnathostome bodyplan. Understanding of the timing and tempo of vertebrate innovations remains, however, mired in a literal reading of the fossil record. Early jawless vertebrates (ostracoderms) exhibit restriction to shallow-water environments. The distribution of their stratigraphic occurrences therefore reflects not only flux in diversity, but also secular variation in facies representation of the rock record. Using stratigraphic, phylogenetic and palaeoenvironmental data, we assessed the veracity of the fossil records of the jawless relatives of jawed vertebrates (Osteostraci, Galeaspida, Thelodonti, Heterostraci). Non-random models of fossil recovery potential using Palaeozoic sea-level changes were used to calculate confidence intervals of clade origins. These intervals extend the timescale for possible origins into the Upper Ordovician; these estimates ameliorate the long ghost lineages inferred for Osteostraci, Galeaspida and Heterostraci, given their known stratigraphic occurrences and stem–gnathostome phylogeny. Diversity changes through the Silurian and Devonian were found to lie within the expected limits predicted from estimates of fossil record quality indicating that it is geological, rather than biological factors, that are responsible for shifts in diversity. Environmental restriction also appears to belie ostracoderm extinction and demise rather than competition with jawed vertebrates.     

A partial skeleton of a new fossil loon (Aves, Gaviiformes) from the early Oligocene of Germany with preserved stomach content

A partial skeleton of a new fossil loon (Aves, Gaviiformes), ?Colymboides metzleri n.sp., is described from the early Oligocene (Rupelian) of Frauenweiler in Germany. The new species resembles the early Miocene species Colymboides minutus in size and overall morphology, but differs in several osteological details. The specimen represents the first associated remains of an early Tertiary loon. Preserved stomach content further provides the first direct evidence that early Tertiary loons were already specialized towards a piscivorous diet, hunting fishes in a marine environment.Communicated by F. Bairlein     

Scolecophidia (Serpentes) of the Late Oligocene and Early Miocene,North America,and a fossil history overview

An abundant fossil record of the snake clade Scolecophidia exists in Europe; however, the minute snake is noticeably absent in reports about the North American Paleogene and Neogene. Presented here are four localities from Florida, USA, that contain scolecophidian remains older than the Pleistocene: Thomas Farm (late Early Miocene, Hemingfordian Land Mammal Age, LMA), Live Oak (Oligocene-Miocene transition, latest Arikareean LMA), White Springs 3B (late Arikareean LMA), and Brooksville 2 (Late Oligocene, middle Arikareean LMA). These remains extend their known existence by about 26 m.y. and are now the oldest reported scolecophidian remains in North America. Molecular evidence on extant scolecophidians concludes that these tiny snakes have a Gondwanan origin. Interestingly, the oldest record of a scolecophidian is from Europe (Belgium) and dates back to the middle Paleocene (MP 1–5). The earliest African record of the snake clade comes from the Paleocene-Eocene boundary in Morocco. The clade is apparently absent from Europe and Middle East deposits dating from the latest Eocene through to the latest Oligocene (MP 19–30) and to the Early Miocene (MN 4). A portion of this time is known as the booid ‘Dark Period’ which represents an apparent response to global aridization and cooling. Scolecophidians appear to re-emerge into the southern Eurasian record in the Early Miocene (MN 4) and become widely dispersed throughout Europe and Middle East. The fossil record of these minute snakes is largely absent in southern Asia and South America. It is possible that the current lack of a decent fossil scolecophidian record outside of Europe and Middle East is due mainly to a bias in the methodology to recover fossils; wet sieving sediments through < 1.0 mm mesh is needed to recover the minuscule vertebrae.     

A new interpretation of the bee fossil Melitta willardi Cockerell (Hymenoptera,Melittidae) based on geometric morphometrics of the wing

Although bees are one of the major lineages of pollinators and are today quite diverse, few well-preserved fossils are available from which to establish the tempo of their diversification/extinction since the Early Cretaceous. Here we present a reassessment of the taxonomic affinities of Melitta willardi Cockerell 1909, preserved as a compression fossil from the Florissant shales of Colorado, USA. Based on geometric morphometric wing shape analyses M. willardi cannot be confidently assigned to the genus Melitta Kirby (Anthophila, Melittidae). Instead, the species exhibits phenotypic affinity with the subfamily Andreninae (Anthophila, Andrenidae), but does not appear to belong to any of the known genera therein. Accordingly, we describe a new genus, Andrenopteryx gen. n., based on wing shape as well as additional morphological features and to accommodate M. willardi. The new combination Andrenopteryx willardi (Cockerell) is established.     

The ontogeny of the entocytherid ostracod Uncinocythere occidentalis (Kozloff & Whitman, 1954) Hart, 1962 (Crustacea)

The Entocytheridae is a cytheroidean family that is known for its commensal mode of life on other crustaceans. However, due to their small size and large sexual dimorphism in the sizes of the carapace, the ontogeny of the entocytherids is poorly understood. This paper documents the basic body plans and pore systems of the entocytherid Uncinocythere occidentalis (Kozloff & Whitman, 1954) Hart, 1962 through ontogeny and compares them with other podocope groups. U. occidentalis has seven juvenile stages, one less than other cytheroidean groups. The general appearance of the limbs during the ontogeny of U. occidentalis is similar to that of other podocope ostracods, such as Limnocythere inopinata (Cytheroidea) Loxoconcha japonica (Cytheroidea),Eucypris virens (Cypridoidea), and Neonesidea oligodentata (Bairdioidea) with the exception of the maxillula. The adult maxillula of U. occidentalis is reduced to just a palp and third masticatory lobe (endite), and the third masticatory lobe and branchial plate of this appendage form later in the ontogeny compared with other podocope species (i.e., these features show post displacemental ontogenetic development). The number of the pore systems of the earliest juvenile (A-7) of U. occidentalis is 10, and is different from that of the corresponding stage of other cytheroidean groups which have 9. This fact, together with the different mode of development of the maxillula, indicates that the entocytherids are not only highly specialized to their commensal mode of life but that they are also phylogenetically distant from most other cytheroidean families, possibly differentiating from the others during the early evolution of the cytherids.     

Postembryonic development of the sea spider Ammothella biunguiculata (Pycnogonida,Ammotheidae) endoparasitic to an actinian Entacmaea quadricolor (Anthozoa,Stichodactylidae) in Izu Peninsula,Japan

Postembryonic developmental stages of an endoparasitic pycnogonid, Ammothella biunguiculata in Izu Peninsula, Japan are described. Eleven stages were identified beginning with a protonymphon larva attached to the male oviger. We found endoparasitic individuals in the host actinian from the second to tenth instar, and forms in the ninth stage to adult were found free-living. This indicates a transition from being endoparasitic to free-living during the ninth to tenth instar stages. The first instar protonymphon attached to the adult male oviger has a gland duct on the anterior margin of each chelifore scape which completely disappears with the second instar. The disappearance of the chelifore gland duct coincides with the beginning of an endoparasitic stage in the development of this species. Although the larval morphology and the postembryonic development of pycnogonids have been summarized by several authors, the present study concludes that much remains to be learnt.     

Exceptionally well-preserved early Eocene fossil reveals cranial and vertebral features of a stem group roller (Aves: Coraciiformes)

Three-dimensionally preserved skulls of small Paleogene land birds are very rare. Here, we describe a cranium and associated partial postcranial remains of an early Eocene stem group roller (Aves: Coraciiformes) from the London Clay of the Isle of Sheppey (England). The fossil shows features of the skull and vertebral column in great detail. It is distinguished from extant Coraciidae and Brachypteraciidae in several presumably plesiomorphic characteristics, which are likely to reflect differences in diet and/or foraging strategy between Eocene and extant rollers. Preserved stomach contents in other early Eocene fossils indicate that fruits were a regular part of the diet of stem group rollers. The extant Coraciidae and Brachypteraciidae, by contrast, almost exclusively feed on larger-sized invertebrates and small vertebrates, which are usually dispatched by beating before being swallowed. Stronger biting forces as well as the characteristic prey manipulation behavior of extant rollers may account for some of the observed differences in the cranial and vertebral morphology of the fossil and extant taxa, but the exact functional correlations remain elusive. We furthermore identify a previously undescribed cranial feature of rollers: a very large foramen for the ramus occipitalis of the arteria ophthalmica externa, which is of unknown functional significance and constitutes a potentially promising research target for future studies.     

Floral development of Hydrocera and Impatiens reveals evolutionary trends in the most early diverged lineages of the Balsaminaceae

Background and Aims

Balsaminaceae consist of two genera, the monospecific Hydrocera and its species-rich sister Impatiens. Although both genera are seemingly rather similar in overall appearance, they differ in ecology, distribution range, habitat preference and morphology. Because morphological support for the current molecular phylogenetic hypothesis of Impatiens is low, a developmental study is necessary in order to obtain better insights into the evolutionary history of the family. Therefore, the floral development of H. triflora and I. omeiana was investigated, representing the most early-diverged lineage of Impatiens, and the observations were compared with the literature.

Methods

Flowers at all developmental stages were examined using scanning electron microscopy and light microscopy.

Key results

In Hydrocera, two whorls of five free perianth primordia develop into a less zygomorphic perianth compared with its sister genus. The androecial cap originates from five individual stamen primordia. Post-genital fusion of the upper parts of the filaments result in a filament ring below the anthers. The anthers fuse forming connivent anther-like units. The gynoecium of Hydrocera is pentamerous; it is largely synascidiate in early development. Only then is a symplicate zone formed resulting in style and stigmas. In I. omeiana, the perianth is formed as in Hydrocera. Five individual stamen primordia develop into five stamens, of which the upper part of the filaments converge with each other. The gynoecium of I. omeiana is tetramerous; it appears annular in early development.

Conclusions

Comparison of the present results with developmental data from the literature confirms the perianth morphocline hypothesis in which a congenital fusion of the parts of the perianth results in a shift from pentasepalous to trisepalous flowers. In addition, the development of the androecial cap and the gynoecium follows several distinct ontogenetic sequences within the family.     

Margolisius abditus n. gen., n. sP. (Copepoda: Lernaeopodidae) from gill lamellae of a remora (Remora remora) collected in the Gulf of California

Margolisius abditus n. gen., n. sp. (Copepoda: Lernaeopodidae) is described from female specimens collected from gill lamellae of a remora, Remora remora (L.), captured in the Gulf of California near Punta Arena, Baja California. Comparison of this species with 13 lernaeopodid genera with which it shares (a) absence of posterior trunk processes; (b) presence of a relatively long cylindrical cephalothorax, usually reflected along the dorsal surface of the trunk; and (c) a marine habitat showed that it cannot be placed in any of them, thus necessitating establishment of a new genus. Margolisius abditus n. sp. is the smallest known lernaeopodid species, its ovigerous females measuring about 0.5 mm in total length.     

An evolutionary approach reveals a high protein-coding capacity of the human genome

We developed a new evolutionary method for identifying exons from genomic sequences and found 19000 potential coding exons that are absent from all existing annotations of the human genome. Of these, 13700 satisfied very stringent criteria and can with confidence be considered as novel exons. Evidently, a large number of new human genes can be identified using evolutionary approaches.     

Mitogenomic evaluation of the unique facial nerve pattern as a phylogenetic marker within the percifom fishes (Teleostei: Percomorpha)

Percomorpha has been described as the “(unresolved) bush at the top” of the teleostean phylogenies and its intrarelationships are intrinsically difficult to solve because of its huge diversity (>15,000 spp.) and ill-defined higher taxa. Patterns of facial nerves, such as those of the ramus lateralis accessorius (RLA), have been considered as one of the candidate characters to delimit a monophyletic group within the percomorphs. Six families of the suborder Percoidei (Arripidae, Dichistiidae, Kyphosidae, Terapontidae, Kuhliidae, and Oplegnathidae) and suborder Stromateoidei (including six families) share the unique pattern 10 of RLA and it has been suggested that those fishes form a monophyletic group across the two perciform suborders. To evaluate the usefulness of the RLA pattern 10 as a phylogenetic marker within the percomorphs, we newly determined whole mitochondrial genome (mitogenome) sequences for the 13 species having RLA pattern 10 and their putatively, closely-related species (5 spp.). Unambiguously aligned sequences (14,263 bp) from those 18 species plus 50 percomrphs and two outgroups (total 70 species) were subjected to partitioned maximum likelihood and Bayesian analyses. The resulting trees clearly indicated that there were at least two independent origins of the unique facial nerve pattern: one in a common ancestor of Kyphosidae, Terapontidae, Kuhliidae, and Oplegnathidae and another one in that of the percoid Arripidae and Stromateoidei. Thus further detailed anatomical studies are needed to clarify the homology of this character between the two lineages. It should be noted that the latter two taxa (Arripidae and Stromateoidei) formed an unexpected, highly-supported monophyletic group together with Scombridae and possibly Chiasmodontidae and Bramidae, all lacking RLA pattern 10 (the former two are members of other perciform suborders Scombroidei and Trachinoidei, respectively). This novel, trans-subordinal clade has never been suggested by any morphological studies, although they share a common ecological characteristic, dwelling in the pelagic realm and often associated with long-distance migrations.     

The morphology of Cercophora palmicola (Lasiosphaeriaceae)

A detailed study of ascomal morphology and development in Cercophora palmicola showed that ontogeny is ascohymeniaceous, giving rise to an ostiolate perithecium. Ascomal initials consist of a coiled ascogonium surrounded by several layers of hyphae whose cells become pseudoparenchymatous. The centrum of the young ascoma is composed of a few rows of large, thin-walled pseudoparenchymatous cells that line the ascomal wall, with the central region filled by tightly packed, filamentous paraphyses. The ascogenous system forms along the inside of the layer of pseudoparenchymatous cells at the base of the paraphyses and gives rise to unitunicate asci that grow up among the paraphyses. The wall of the mature perithecium is greatly thickened. It is composed of three regions: a thin outer region of darkly pigmented, angular cells with thickened walls; a broad central region of cells with gelatinized walls; and a thin inner region of flattened cells. Ascomal ontogeny in C. palmicola conforms well to the Sordaria type of development, as defined by Huang.     

Anatomical changes and evolutionary trends in the foliar epidermis of extant and fossil Euro-Mediterranean oaks (Fagaceae)

The differentiation of foliar epidermis structures, cuticles, stomata, and indumentum of most of the extant Euro-Mediterranean taxa ofQuercus have been studied by light and scanning electron microscopy, and compared with other genera and fossil material. Results allow the recognition of the subgg.Sclerophyllodrys, Cerris andQuercus, and of various sections and even individual species. The cyclocytic stomata type, regarded as plesiomorphic, is found in the geologically oldest representatives of the familiy (Dryophyllum, resp.Eotrigonobalanus) and in the relatively old, evergreen to semi-evergreen species ofQuercus subgg.Sclerophyllodrys andCerris. These taxa also have relatively thick and smooth cuticles. Anomocytic stomata, thinner cuticles and the presence of crystalline wax flakes are regarded as apomorphic features and characterize the deciduous taxa of subg.Quercus. These changes are interpreted as ecological adaptations to the changing climates from the Tertiary to the present. An analysis of the various character combinations found in macrofossils and the often poor species separation inQuercus suggest that hybridization has played a major role in the evolution of the Euro-Mediterranean oaks.     

Biphasic assembly of the murine intestinal microbiota during early development

The birth canal provides mammals with a primary maternal inoculum, which develops into distinctive body site-specific microbial communities post-natally. We characterized the distal gut microbiota from birth to weaning in mice. One-day-old mice had colonic microbiota that resembled maternal vaginal communities, but at days 3 and 9 of age there was a substantial loss of intestinal bacterial diversity and dominance of Lactobacillus. By weaning (21 days), diverse intestinal bacteria had established, including strict anaerobes. Our results are consistent with vertical transmission of maternal microbiota and demonstrate a nonlinear ecological succession involving an early drop in bacterial diversity and shift in dominance from Streptococcus to Lactobacillus, followed by an increase in diversity of anaerobes, after the introduction of solid food. Mammalian newborns are born highly susceptible to colonization, and lactation may control microbiome assembly during early development.     

The earliest fossil record of a modern-type piciform bird from the late Oligocene of Germany

Summary Presented here is a record of a piciform bird from a late Oligocene fissure filling from Germany. This is the earliest known fossil record of a modern-type piciform bird and the only one from deposits earlier than Miocene. The specimen, an isolated tarsometatarsus, is similar in size and proportions to the tarsometatarsus of the recent Cardinal-Woodpecker (Dendropicos fuscescens, Picidae). However, owing to its fragmented state a reliable assignment to any of the recent piciform families is not possible.

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Der älteste Nachweis eines modernen Spechtvogels aus dem späten Oligozän Deutschlands

Zusammenfassung Ein Nachweis eines Spechtvogels wird aus einer spätoligozänen Spaltenfüllung Deutschlands beschrieben. Es ist der bisher älteste Nachweis eines modernen Spechtvogels und der einzige aus vor-miozänen Ablagerungen. Das Exemplar, ein isolierter Tarsometatarsus, ähnelt in Größe und Proportionen dem Tarsometatarsus des rezenten Kardinalspechts (Dendropicos fuscescens, Picidae). Aufgrund seiner fragmentarischen Erhaltung ist jedoch keine zuverlässige Zuordnung zu einer der rezenten Familien spechtartiger Vögel möglich.

     

Intralacustrine movements of Galaxias maculatus (Galaxiidae) and Ondontesthes microlepidotus (Atherinidae) during their early life history

Synopsis Galaxias maculatus and Odontesthes microlepidotus undertook significant habitat shifts in a small Araucanian lake during their early life history. After hatching in the littoral zone, free embryos migrate to the limnetic zone. Later, larvae return to the littoral. A third movement, littoral-limnetic, is suggested through acoustic records of fish in the limnetic zone which correspond with the growth curve of littoral sampled juveniles.     

Studies on skeleton formation in reptiles, v. Patterns of ossification in the skeleton of Alligator mississippiensis DAUDIN (Reptilia, Grocodylia)

Patterns of ossification are described in the endo-and exoskeleton of Alligator mississippiensis. The occurrence of a dermo-supraoccipital is discussed in light of the independence of dermal and endochondral bone. The development of the bony secondary palate is discussed in light of Haeckelian recapitulation. The sequence of ossification in the limb skeleton is shown to differ from the sequence of chondrification of the cartilaginous precursors. Patterns of ossification in Alligator are compared to lepidosaurs in terms of sequence and timing. Important differences relate to ossification patterns in the limb skeleton: lepidosaurs show a dominance of digit III > IV > II > I > V, whereas Alligator shows a dominance of digits III > II> IV > I > V in the ossification process. Ontogenetic repatterning in the ossification of the axial skeleton is discussed as it bears on the serial homology of dorsal ribs, sacral ribs and caudal ribs (transverse processes).     

Taxonomy and evolutionary patterns in the fossil Hyaenidae of Europe

We review the larger pattern of appearance of the Hyaenidae in Europe and outline their part in the turnover of the guild of larger Carnivora that occurs across the Miocene-Pliocene boundary. The earliest record of the family is in MN4, although the patchy nature of the earliest records makes it difficult to be certain about the continent of origin. There is a clear pattern of morphological evolution over that long timespan, from the earliest viverrid- and herpestid-like forms through dog-like and more cursorial taxa to the larger, bone-crunching animals of the later Miocene and the Pliocene-Pleistocene epochs. Miocene dog-like hyaenas may indicate that social hunting had emerged by that time, while the appearance of larger species means that hyaena-accumulated bone assemblages may potentially occur in any late Miocene to Pleistocene locality.