The diversification of Bees.

Bees (Anthophila) are generally accepted to have arisen during the Mesozoic, but estimates of exactly when vary considerably. The group are not well known in the fossil record (at least in part because many early palaeontologists tended to ignore Insect fossils in Mesozoic beds, happily destroying them in the quest for Dinosaurs and other large, glamorous Vertebrates), with the earliest putative Bee being Melittosphex burmensis, from 100-110 million-year-old Burmese Amber, which some palaeoentomologists  argue is a Crabronid Wasp (the group of Wasps most closely related to Bees), while the oldest universally accepted Bee is Cretotrigona prisca, a 65-million-year-old probable Stingless Bee from New Jersey Amber. Attempts to date the origin of the group using genetic molecular dating techniques have, to date, been equally problematic, with origin dates varying from 275 million years ago (early Permian) to 147 million years ago (Late Jurassic).

An artists impression of Cretotrigona prisca, from the Late Cretaceous, the oldest universally accepted Bee. Michael Rothman in Engel (2000).

This lack of knowledge about the timing of the origin and diversification of Bees presents difficulties for palaeoecologists trying to understand Cretaceous ecosystems. Between 78% and 94% of all modern Flowering Plants (Angiosperms) are pollinated by Animals, with Bees being one of the most important groups. The exact date of origin for the Angiosperms is equally obscure, but the group is known to have existed by the Early Cretaceous and undergone a dramatic radiation during the middle part of the period, so that Late Cretaceous floras are dominated by Flowering Plants. Logically it would be expected that such an outburst of diversity and ecological success would be accompanied by a similar rise in some associated group of pollinators, with Bees being the primary candidate, but to date evidence for this has been lacking.

In a paper published in the Proceedings of the Royal Society: Series B Biological Sciences on 30 January 2013, Sophie Cardinal of the Canadian National Collection of Insects at Agriculture and Agri-Food Canada and Bryan Danforth of the Department of Entomology at Cornell University, publish the results of a new genetic study of the phylogeny of Bees, which examines seven different gene groups and uses a relaxed molecular clock to calibrate this phylogeny from the fossil record (this assumes that any group must have originated before its first occurrence in the fossil record). Since Melittosphex burmensis is not universally accepted as a Bee it was not used in the study, and since Cretotrigona prisca is not universally accepted as a member of the modern Meliponini (Stingless Bees) it is treated only as a Bee, not a Stingless Bee.

Cardinal & Danforth produced a dated molecular phylogeny which suggested that the Bees arose in the Early Cretaceous, around 140 million years ago, and differentiated into the modern Bee groups (except the Leaf-cutter Bees, Megachilini) during the Middle Cretaceous, with a latest common ancestor of all modern bees living between 113 and 132 million years ago. This supports the idea that Bees underwent a major evolutionary radiation at the same time as Flowering Plants, and that the diversification of both groups was driven by the plant/pollinator relationship.

Time calibrated phylogeny of bees based on analysis 3 (age of the root node sampled from a normal distribution with a mean of 140 and a s.d. of five and tree constrained to have the same relationships as the MRBAYES produced tree at the subfamily and taxonomically higher levels). Horizontal bars indicate 95% HPD of estimated divergence times. Posterior probabilities are shown at the right of each node. Cardinal & Danforth (2013).

Cardinal & Danforth did not include trace fossils in their calculations, nevertheless they do observe that their results do confirm the existence of Halictid Bees by the Late Cenomanian, when putative burrows made by the group have been found in Arizona. Conversely their results suggest that the last common ancestor of all modern Leaf-cutter Bees (Megachilini) lived more recently than the Mid-Eocene Messel Shale, where putative damage to leaves caused by members of this group has been found. Cardinal and Danforth suggest that this does not rule out a Leaf-cutter Bee as the cause of this damage, as the group could potentially have existed before the last common ancestor of all its modern members.

See also…

 A Stingless Bee from Colombian copal.

 A new species of Oil Bee from northeast Brazil.

 A new species of Solitary Bee from Peru.

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Predation of Freshwater Mussels in the Early Cretaceous of Spain.

Unionoid Bivalves (Freshwater Mussels) appeared before the beginning of the Triassic, and became the dominant freshwater invertebrates in many freshwater ecosystems early in the Mesozoic, particularly in the Northern Hemisphere. Like marine Molluscs they are subject to a variety of predation, but this has not been widely studied in the fossil record.

In a paper published in the January 2013 edition of the journal Lethaia, David Bermúdez-Rocha of the Universidad de Cantabria, Graciela Delvene of the Museo Geominero at the Instituto Geológico y Minero de España and Ignacio Ruiz-Omeñaca of the Museo del Jurásico de Asturias and the Departamento de Geología at the Universidad de Oviedo describe a series of shells of the Freshwater Mussel Protopleurobema numantina from the Early Cretaceous of the Cameros Basin in northern Spain, showing rounded depressions which they interpret as signs of predation damage.

These depressions do not appear to have been made by any known predator of freshwater Bivalves. They lack the scape marks associated with Gastropod predation, and in addition no shells belonging to carnivorous Gastropods have been found at the locality. The depressions also are a different shape to those associated with Turbelarian Flatworms, and are to large to have been caused by nematodes.

Left valve of a Protopleurobema numantina shell showing damage 

in external (A), posterior (B) and internal (C) views. Bermúdez-Rocha et al. (2013).

 
Bermúdez-Rocha et al. interpret this damage as having been caused by crushing by the tooth of a large vertebrate, and furthermore suggest that these teeth much have been blunt and conical in profile to have produced indentations of this profile. The beds that produced the shells also produce fragmentary remains of Ganoid Fish, however the teeth of these are two small and tightly packed to have caused this damage, suggesting that a non-Fish predator was probably responsible. Theropod Dinosaurs typically have sharp teeth with a flattened profile, which would again be unlikely to produce damage to shells in this way.

Crocodyliforms have blunted, conical teeth, and a number of species are known to have been present in the Cameros Basin during the Early Cretaceous, with one species, Goniopholis, producing teeth of the right proportions to cause the shell damage seen. Small Bivalves are not an obvious prey item for a large Crocodyliform, however several modern species, including the Chinese Alligator (Alligator sinensis), the Mugger Crocodile (Crocodylus palustris) and the Gharial (Gavialis gangeticus) are known to seek out and consume Freshwater Bivalves when other prey is scarce, and Bermúdez-Rocha et al. suggest that similar behavior in a Jurassic Crocodyliform would not be surprising.

Schematic diagram showing the formation of dents and perforations in bivalve shells affected by perpendicular point loading by a 

tooth. (A1–A2) formation of a dent, without the development of adjacent fractures. (B1–B2) development of a dent with inward fractures and 

partial displacement of the shell. (C1–C2), formation of a perforation with complete detachment of the shell affected by point loading, with formation 

of inward-diverging fractures in the perforation’s perimeter. (D1–D2) development of a perforation with adjacent spall marks. 

Bermúdez-Rocha et al. (2013).

See also Opportunistic Bivalves during the Early Jurassic Toarcian Oceanic Anoxic Event, A new species of Pea Clam from the Miocene of Bosnia and Herzegovina, Iceberg damage in an Antarctic Clam, The evolution of Galeommatoid Bivalves and Symbiosis and the success of Galeommatoid Bivalves.

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New Ommatid Beetles from the Mesozoic of China.

The Ommatidae are generally considered to be one of the most primitive groups of Beetles, possibly close to the origin of the group. There are six known extant species in two genera, restricted to arid subtropical regions of Australia and South America. A number of fossil species have also been described, from Mesozoic sites across Eurasia; since Beetles are known to have been in existence by the late Carboniferous, if the Ommatidae are close to the origin of the group, then the fossil record of the earliest members is apparently missing.

The extant Ommatid Beetle, Omma rutherfordi, from the Twin Creeks Community Conservation Reserve in Western Australia. Farhan Bokhari.

In a paper published in the journal BMC Evolutionary Biology on 9 July 2012, a team of scientists led by Jingjing Tan of the Key Laboratory of Zoological Systematics and Evolution at the Institute of Zoology of the Chinese Academy of Sciences, and the College of Life Sciences at Capital Normal University describe four new species of Ommatid Beetles from the Mesozoic of China.

The first new species described is placed in the genus Pareuryomma, which already contains one species (Pareuryomma tylodes) from the Early Cretaceous Jehol Biota of northeast China. This is Pareuryomma ancistrodonta, where ancistrodonta means 'curved tooth', in reference to the shape of the mandible. This comes from the Middle Jurassic Jiulongshan Formation at Daohugou Village in Inner Mongolia.

Pareuryomma ancistrodonta, a new Ommatid Beetle from the Middle Jurassic of Inner Mongolia. Tan et al. (2012).

The second new species described is also placed in the genus Pareuryomma. This is Pareuryomma cardiobasis, where cardiobasis means 'heart-shaped' a reference to a marking on the Beetle's thorax. Pareuryomma cardiobasis comes from the Early Cretaceous Yixian Formation at Chaomidian Village in Liaoning Province, the same locality as Pareuryomma tylodes.

Pareuryomma cardiobasis, a new Ommatid Beetle from the Early Cretaceous of Liaoning Province. Tan et al. (2012).

The third new species is placed in the genus Omma; this species is still extant, with four known species in Australia, as well as eleven previously described species from the Late Triassic to Early Cretaceous of England, Kyrgyzstan, Mongolia, Kazakhstan, Germany and Russia. This new species is named as Omma delicata, where delicata means 'delicate' a reference to the small size of the fossil. It comes from the Middle Jurassic Jiulongshan Formation of Daohugou Village in Inner Mongolia.

Omma delicata, a new Ommatid Beetle from the Middle Jurassic of Inner Mongolia. Tan et al. (2012).

The final new species described is placed in the genus Tetraphalerus, a genus that includes two extant species from South America and 23 previously described fossil species from the Mesozoic of Eurasia. It is named Tetraphalerus decorosus, where decorosus means 'well-preserved'. It also comes from the Middle Jurassic Jiulongshan Formation of Daohugou Village in Inner Mongolia.

Tetraphalerus decorosus, a new Ommatid Beetle from the Middle Jurassic of Inner Mongolia. Tan et al. (2012).

See also Two new species of Rove Beetle from Zhejiang Province, China and New species of Bess Beetle from Guatemala.

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Two new species of True Bug from the Mesozoic of China.

The Hemiptera, or True Bugs, are one of the most numerous and widespread groups of Insects, but there taxonomy is poorly understood. Modern genetic studies have suggested that many long established taxonomic relationships are in fact incorrect, but have not been able to propose alternative models for the taxonomy of the group. An alternative method of determining the relationship between living groups of animals is to study their fossil record, though this can be difficult with Insects, as fossils are often fragmentary, and, until fairly recently, were often overlooked in favor of larger, more spectacular fossils.

To this end a team of scientists led by Yunzhi Yao of the Key Laboratory of Insect Evolution and Environmental Changes at Capital Normal University and the State Key Laboratory of Palaeobiology and Stratigraphy at the Nanjing Institute of Geology and Palaeontology have been collecting fossil Bugs from a number of sites in China noted for their exceptionally preserved Insect faunas. In a paper published in the journal PLoS One on 24 May 2012, they describe two new species of True Bug from the Late Jurassic to Early Cretaceous, Yixian Formation of Liaoning Province, China, and the implications of these new species for the classification of the group.

The first of these new species is Venicoris solaris, the Solar Vein-bug. It is a ~10 mm Bug from Chaomidian Village, near Beipiao City, described from 85 male and 125 female specimens.

Photographs of Venicoris solaris from the Yixian Formation of Liaoning Province, China. (A) Male under ethanol. (B) Male, dry. (C & D) Females under ethanol. Scale bar is 2 mm. Yao et al. (2012).

Interpretive drawings of Venicoris solaris. (A) Male. (B) Female. Scale bar is 2 mm. Yao et al. (2012).

The second species is named as Clavaticoris zhengi, Zheng's Claval Bug, in honor of Dr. Leyi Zheng of the Institute of Entomology at the College of Life Science at Nankai University. It is an 18.5 mm bug from the same locality as Venicoris solaris, named from two female and one male specimens.

Photographs of Clavaticoris zhengi. (A & B) Female under air; two halves of same specimen, obverse and reverse from rock that has been split. (C) Male under ethanol. (D) Female under air. Scale bar is 4 mm. Yao et al. (2012).

Interpretive drawing of female Clavaticoris zhengi (A, above). Scale bar is 2 mm. Yao et al. (2012).

The two new species are together placed in a new Family, the Venicoridae, which Yao et al. suggest may be ancestral to the Trichophora (Sheild Bugs, Chust Bugs, Stink Bugs, Broad-headed Bugs, Leaf-footed Bugs, Squash Bugs, Scentless Plant Bugs, Spurgebugs, Stilt Bugs, True Seed Bugs, Atypical Seed Bugs and several other groups).

See also New species of Leaf-Mining Moth from northern Chile, An Assassin Bug from the Palaeocene of Spitsbergen Island, A fossil termite from the Late Oligocene of northern Ethiopia, New species of moth from Yunnan Province and New species of Owlfly from Morocco.

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