Changes to the Fossil Record of Insects through Fifteen Years of Discovery

The first and last occurrences of hexapod families in the fossil record are compiled from publications up to end-2009. The major features of these data are compared with those of previous datasets (1993 and 1994). About a third of families (>400) are new to the fossil record since 1994, over half of the earlier, existing families have experienced changes in their known stratigraphic range and only about ten percent have unchanged ranges. Despite these significant additions to knowledge, the broad pattern of described richness through time remains similar, with described richness increasing steadily through geological history and a shift in dominant taxa, from Palaeoptera and Polyneoptera to Paraneoptera and Holometabola, after the Palaeozoic. However, after detrending, described richness is not well correlated with the earlier datasets, indicating significant changes in shorter-term patterns. There is reduced Palaeozoic richness, peaking at a different time, and a less pronounced Permian decline. A pronounced Triassic peak and decline is shown, and the plateau from the mid Early Cretaceous to the end of the period remains, albeit at substantially higher richness compared to earlier datasets. Origination and extinction rates are broadly similar to before, with a broad decline in both through time but episodic peaks, including end-Permian turnover. Origination more consistently exceeds extinction compared to previous datasets and exceptions are mainly in the Palaeozoic. These changes suggest that some inferences about causal mechanisms in insect macroevolution are likely to differ as well

On the polymorphism of the bryozoan order Rhabdomesonida

The order Rhabdomesonida includes the following unusual and poorly investigated families : Arthrostylidae, Rhabdomesonidae, Hyphasmoporidae and a new one. Comparable study of gemmation peculiarities and astogeny stages of Rhabdomesonida colonies for the first time made it possible to expose specific types of gemmation and polymorphism development. The latter results in the development of several types of zooecia in every colony, which appear to be frame residues of zooids with different morphological and functional characters. This is the most important feature of the order in question. The historical development of the order was accompanied by parallel modification of gemmation types within every family, from primitive spiral type, present in the older genera, to more complicated one connected with the differentiation of zooids. Spiral and complex types of gemmation are the most characteristic ones of all families. Astogenetic development of the colonies with their complex type of gemmation is divided into four stages : 1. Ancestrula 2. Gemmation of primary zooecia 3. Gemmation of secondary zooecia 4. Mature stage Zooecia. Apparent primary and secondary zooecia are distinguished not only by the sequence of their emergence in the colonies but also by their morphology. Acanthopores. Acanthopores of Rhabdomesonida and those of Trepostomida show sharp morphological distinction. Within the order of Rhabdomesonida, two types of acanthopores were established. One of them is typical for the colonies with complex gemmation and the second one for spiral gemmation. Metapores. On the last stage of astogenetic formation of rhabdomesonid colonies metapores appeared in the intervals between zooecia. The polymorphism or zooid differentiation in the colonies of most rhabdomesonid genera appear as a result of specialization and functional division within the whole colony and should be considered as the rise of colonial individuality, from one side, and attenuation of zooid individuality from the other.L'ordre des Rhabdomesonida comprend les familles suivantes peu communes et mal connues : Arthrostylidae, Rhabdomesonidae, Hyphasmoporidae et une nouvelle famille. L'étude comparative des particularités de la gemmation et des étapes de l'astogenèse des colonies de Rhabdomesonida pour la première fois fait qu'il est possible d'exposer des types spécifiques de gemmation et de développement polymorphe. Le dernier résulte dans le développement de plusieurs types de zoécies dans chaque colonie, qui apparaissent être des reliquats de zoécies avec différents caractères morphologiques et fonctionnels. Ceci est le caractère le plus important de l'ordre en question. Le développement historique de l'ordre s'est accompagné de modifications parallèles des types de gemmation à l'intérieur de chaque famille : du type spiral primitif présent dans les plus anciens genres, jusqu'au type plus compliqué connecté avec la différenciation des zoécies. Les types de gemmation (spiral et complexe) sont les caractéristiques principales de toutes les familles. Le développement astogénique des colonies avec leur type complexe de gemmation est divisé en 4 étapes : 1. ancestrule 2. gemmation des zoécies primaires 3. gemmation des zoécies secondaires 4. âge mûr Zoécies. Les zoécies apparentes primaires et secondaires se distinguent non seulement par la séquence de leur apparition dans la colonie, mais aussi par leur morphologie. Acanthopores. Les acanthopores de Rhabdomesonida et ceux des Trepostomida montrent des distinctions morphologiques nettes. À l'intérieur de l'ordre des Rhabdomesonida, deux types d'acanthopores sont établis. L'un d'eux est typique des colonies à gemmation complexe et le second des colonies à gemmation spirale. Métapores. Dans la dernière phase de la formation astogénique des colonies de Rhabdomesonida les métapores apparaissent dans les intervalles entre les zoécies. Le polymorphisme ou la différenciation des zoécies dans les colonies de la plupart des genres de Rhabdomesonida apparaît comme un résultat de spécialisation et division fonctionnelle à l'intérieur de la colonie toute entière et pourrait être considéré comme l'accroissement de l'individualité coloniale, d'une part, et comme l'atténuation de l'individualité zoïdiale d'autre part.Gorjunova R. V. On the polymorphism of the bryozoan order Rhabdomesonida. In: Documents des Laboratoires de Géologie de la Faculté des Sciences de Lyon. Hors série n°3, 1975. Bryozoa 1974 – Proceedings of the third Conference International Bryozoology Association – Lyon (fasc. 1) pp. 59-64