Specialized springtail predation by Loricera beetles: An example of evolutionary stasis across the K-Pg extinction

Dear Editor,The Cretaceous-Paleogene(K-Pg)mass extinction precipitated one of the most profound restructurings of biodiversity in recent geological history.Despite the extinction of many iconic groups,particularly the non-avian dinosaurs,there is emerging evidence that previously overlooked taxa experienced stark morphological and evolutionary stasis.In this study,we report both adult and larva of beetles of the genus Loricera preserved in mid-Cretaceous Kachin amber(Figure 1),which display striking similarity to extant congeners,indicating a stasis of their specialized feeding behavior persisting at least 100 million years.

Jurassic integrative stratigraphy and timescale of China

The Jurassic stratigraphy in China is dominated by continental sediments. Marine facies and marine-terrigenous facies sediment have developed locally in the Qinghai-Tibet area, southern South China, and northeast China. The division of terrestrial Jurassic strata has been argued, and the conclusions of biostratigraphy and isotope chronology have been inconsistent.During the Jurassic period, the North China Plate, South China Plate, and Tarim Plate were spliced and formed the prototype of ancient China. The Yanshan Movement has had a profound influence on the eastern and northern regions of China and has formed an important regional unconformity. The Triassic-Jurassic boundary(201.3 Ma) is located roughly between the Haojiagou Formation and the Badaowan Formation in the Junggar Basin, and between the Xujiahe Formation and the Ziliujing Formation in the Sichuan Basin. The early Early Jurassic sediments generally were lacking in the eastern and central regions north of the ancient Dabie Mountains, suggesting that a clear uplift occurred in the eastern part of China during the Late Triassic period when it formed vast mountains and plateaus. A series of molasse-volcanic rock-coal strata developed in the northern margin of North China Craton in the Early Jurassic and are found in the Xingshikou Formation, Nandailing Formation, and Yaopo Formation in the West Beijing Basin. The geological age and markers of the boundary between the Yongfeng Stage and Liuhuanggou Stage are unclear. About 170 Ma ago, the Yanshan Movement began to affect China. The structural system of China changed from the near east-west Tethys or the Ancient Asia Ocean tectonic domain to the north-north-east Pacific tectonic domain since 170–135 Ma. A set of syngenetic conglomerate at the bottom of the Haifanggou or Longmen Fms. represented another set of molasse-volcanic rock-coal strata formed in the Yanliao region during the Middle Jurassic Yanshan Movement(Curtain A1). The bottom of the conglomerate is approximately equivalent to the boundary of the Shihezi Stage and Liuhuanggou Stage. The bottom of the Manas Stage creates a regional unconformity in northern China(about 161 Ma, Volcanic Curtain of the Yanshan Movement, Curtain A2). The Jurassic Yanshan Movement is likely related to the southward subduction of the Siberian Plate to the closure of the Mongolia-Okhotsk Ocean. A large-scale volcanic activity occurred in the Tiaojishan period around 161–153 Ma. Note that 153 Ma is the age of the bottom Tuchengzi Formation, and the bottom boundary of the Fifth Stage of the Jurassic terrestrial stage in China should have occurred earlier than this. This activity was marked by a warming event at the top of the Toutunhe Formation, and the change in the biological assembly is estimated to be 155 Ma. The terrestrial Jurassic-Cretaceous boundary(ca. 145.0 Ma) in the Yanliao region should be located in the upper part of Member 1 of the Tuchengzi Formation, the Ordos Basin in the upper part of the Anding Formation, the Junggar Basin in the upper part of the Qigu Formation, and the Sichuan Basin in the upper part of the Suining Formation The general characteristics of terrestrial Jurassic of China changed from the warm and humid coal-forming environment of the Early-Middle Jurassic to the hot, dry, red layers in the Late Jurassic. With the origin and development of the Coniopteris-Phoenicopsis flora, the Yanliao biota was developed and spread widely in the area north of the ancient Kunlun Mountains, ancient Qinling Mountains, and ancient Dabie Mountain ranges in the Middle Jurassic, and reached its great prosperity in the Early Late Jurassic and gradually declined and disappeared and moved southward with the arrival of a dry and hot climate.

The Early Cretaceous Hemeroscopid larva fossils from Beijing,China

More than 100 Hemeroscopid larva fossils were discovered from the Lower Cretaceous in Southwest Beijing, which effectively ends the discussion of morphology and makes it more complete. It is assigned within the Libellu-loidea, and shows close evolutionary correlations with modern Libellulidae. Although the wing characters of adult Hemeroscopus from the same formation indicates the close relationship to Aeschnoidea, we suggest that the larvae and the adults were the same species. Therefore, it probably shows the evolutionary ancestors of Libellulidae. Being the fundamental species discriminating Jehol Entomofauna and Lushangfen Entomofauna, Hemeroscopus bears great significance in the study of stratigraphy.

Gill rays of primitive vertebrate Yunnanozoon from Early Cambrian: a first record

Yunnanozoans(including Yunnanozoon and Haikouella)are important representatives of the primitive vertebrates in the Early Cambrian Chengjiang fauna.For Yunnanozoans,we know less about Yunnanozoon than about Haikouella due to the poor preservation of Yunnanozoon.Up to now,there have been some reports that Haikouella had developed gill rays,while there have been no reports on Yunnanozoon.In this paper,we described our new findings of the distinct gill rays of Yunnanozoon lividum based on new well-preserved material collected from the Lower Cambrian Maotianshan Shale in Xiaolantian of Yunnan Province,China.This study provides new data on the evolutionary relationship of the primitive vertebrates and their early evolution.

Minute clubbed beetles with cephalic horns in mid-Cretaceous amber from northern Myanmar(Coleoptera:Monotomidae)

A new fossil species of Monotomidae,Cretakarenni shaoi Li&Cai,sp.nov.,is reported from the mid-Cretaceous Burmese amber.The new species is attributed to the extinct genus Cretakarenni Peris&Delclòs,2015 primarily based on the paired setose projections on head,apparently 1-segmented antennal club,and transverse procoxal cavities with exposed trochantins.It differs from the previously reported C.birmanicus Peris&Delclòs from the same deposit in the more narrowly separated projections(cephalic horns)on vertex and the absence of elytral absutural lines.Our discovery of a new monotomid species from the mid-Cretaceous amber highlights the palaeodiversity and morphological disparity of the family in the late Mesozoic.