Info

Rasnitsyn, 1988a

and various other orders with 1% or less. Among the more impressive insects are diverse odonates, roaches with long ovipositors (which is one of the latest occurrences of this feature in the fossil record), beautiful Kalligrammatidae (Figure 9.25) and Raphidioptera (Neuropterida) (Figure 9.7), diverse Brachycera, and some early Apocrita (Figures 11.10, 11.16). Karatau is a testament to how views of insect evolution can be dramatically affected by the discovery of just one exceptional fossil deposit.

North America. Though no Jurassic insect deposits were indicated from eastern North America in the map by Eskov (2002), the earliest such records from this continent were from the Early Jurassic of Massachusetts (Hitchcock, 1858). Sparse insects occur in lacustrine sediments of the ancient rift lakes of the Newark Supergroup, which is nicely reviewed and discussed by Huber et al. (2003). These include beetle elytra, a roach, abundant larvae (Mormolucoides), and various undetermined fragments. One type of beetle is Holcoptera, which is a dytiscid with distinctive patterning on the elytra and occurs from the Late Triassic to the Early Cretaceous. Assorted localities from western North America include two mid- and one Late Jurassic site. The Late Jurassic

2.51. A small outcrop of the Late Jurassic-aged Karabastau Formation at Karatau, central Kazakhstan. The Karabastau Formation is the world's most prolific source of Jurassic insects. Seventy years of study of the insects from Karatau by specialists at the Paleontological Institute in Moscow have revealed most of what we know about Jurassic insect life. Photo: Paleontological Institute, Moscow.

2.51. A small outcrop of the Late Jurassic-aged Karabastau Formation at Karatau, central Kazakhstan. The Karabastau Formation is the world's most prolific source of Jurassic insects. Seventy years of study of the insects from Karatau by specialists at the Paleontological Institute in Moscow have revealed most of what we know about Jurassic insect life. Photo: Paleontological Institute, Moscow.

(Kimmeridgian: 152 mya) Morrison Formation has preserved rare caddisfly cases. The Toldito Formation (Callovian: 160 mya) of northern New Mexico has preserved nymphs of two species of predatory nepomorphan water bugs (Polhemus, 2000). The Sundance Formation of northern Wyoming and southern Montana (also Callovian) is probably the most diverse Jurassic deposit in North America for insects, albeit they are poorly preserved. They include about 15 species of aquatic Hemiptera (nepomorphs), Coleoptera (Dytiscidae, including Holcoptera), and rare trichopteran cases (Santiago-Blay et al., 2001).

Antarctica. Jurassic insects from Antarctica are of great bio-geographic interest because they should help reveal the nature of nonglaciated Antarctica, at a time when it was joined to the other southern continents. Isolated insect specimens have been recovered from strata of undetermined Jurassic ages at Mount Flora, Grahamland (Zeuner, 1959), and two sites in southern Victoria Land (Carapace Nunatak and Beardmore Glacier area) (Carpenter, 1969; Tasch, 1973, 1987).

The only other gondwanan Jurassic insects are found in a deposit from the Early Jurassic (Kota Formation) of Andhra Pradesh in central India (e.g., Rao and Shah, 1959) (India was connected to Africa and Antarctica in the Jurassic), scattered occurrences from southern South America, and one locality each in Africa and New Zealand. Insects from the Jurassic of India are the most diverse yet known from Gondwana, and they include Auchenorrhyncha, Blattodea, Coleoptera, Diptera, Ephemeroptera, Heteroptera, Hymenoptera, and Neuropterida (Tasch, 1987; Mostovski and Jarzembowski, 2000).

0 0

Post a comment