Page 395 - Introduction to Paleobiology and The Fossil Record

382 INTRODUCTION TO PALEOBIOLOGY AND THE FOSSIL RECORD

Box 14.7 Insects take to the airways

Fossil insects with functional wings are first reported from Mid Carboniferous strata. These insects

were extraordinary (Fig. 14.20); the dragonfl y Meganeura had an incredible wingspan of 70 cm.
Intense aerobic activity such as powered flight suggests that atmospheric oxygen levels at the time

were unusually high. But how effective was Meganeura as a flyer? Robin Wootton and his colleagues

(1998) have identified so-called smart features that capitalized on both upstroke and downstroke
movements of the animal’s large wings. This form of smart engineering helps depress the trailing

edges of the wings, rather like an aircraft’s flaps during takeoff and landing, and helps wing twisting.
It is unlikely that the giant Mid Carboniferous dragonflies could actually hover like modern forms

but they had good maneuvrability. These winged giants had already developed a predatory lifestyle
and, being about the size of a seagull, would have made a highly visible addition to terrestrial life
in the forests of the Carboniferous (see p. 488).

Figure 14.20 Giant Carboniferous dragonflies from Ayr, Scotland. p, prothoracic lobe; r, rostrum.
Scale bar is in millimeters. (Courtesy of Ed Jarzembowski.)

The cirripedes or barnacles have shells, or The malacostracans include two subclasses,
capitula (singular, capitulum), consisting of the phyllocarids and the eumalacostracans.
several plates and these animals are adapted The phyllocarids have large bivalved cara-
to an encrusting lifestyle. Two groups, the paces, seven abdominal somites and a telson
acorn barnacles and goose barnacles, have with a pair of furcae (forked extensions; sin-
contrasting life strategies. The acorn barna- gular, furca), extending posteriorly. Canadas-
cles, such as Balanus, have capitula consisting pis from the Burgess Shale may be one of
of overlapping plates and they are attached to the first crustaceans. Living phyllocarids are

rocks and other shells. The group rapidly usually minute, in contrast to their larger
diversified from an origin during the Late Cre- Paleozoic ancestors. The eumalacostracans

taceous and are locally common. The goose include decapods – shrimps, lobsters and
barnacles are pseudoplankton, living attached crabs – together with the less common

to floating debris, that have a relatively poor branchiopods. Some of the most spectacular
fossil record. Carboniferous eumalacostracans have been