Archaeopteryx - Paleoecology

Paleoecology

The richness and diversity of the Solnhofen limestones in which all specimens of Archaeopteryx have been found have shed light on an ancient Jurassic Bavaria strikingly different from the present day. The latitude was similar to Florida, though the climate was likely to have been drier, as evidenced by fossils of plants with adaptations for arid conditions and lack of terrestrial sediments characteristic of rivers. Evidence of plants, though scarce, include cycads and conifers while animals found include a large number of insects, small lizards, pterosaurs and Compsognathus.

The excellent preservation of Archaeopteryx fossils and other terrestrial fossils found at Solnhofen indicates that they did not travel far before becoming preserved. The Archaeopteryx specimens found are likely therefore to have lived on the low islands surrounding the Solnhofen lagoon rather than been corpses that drifted in from farther away. Archaeopteryx skeletons are considerably less numerous in the deposits of Solnhofen than those of pterosaurs, of which seven genera have been found. The pterosaurs included species such as Rhamphorhynchus belonging to the Rhamphorhynchidae, the group which dominated the niche currently occupied by seabirds, and which became extinct at the end of the Jurassic. The pterosaurs, which also included Pterodactylus, were common enough that it is unlikely that the specimens found are vagrants from the larger islands 50 km (31 mi) to the north.

The islands that surrounded the Solnhofen lagoon were low lying, semi-arid and sub-tropical with a long dry season and little rain. The closest modern analogue for the Solnhofen conditions is said to be Orca Basin in the northern Gulf of Mexico, though that is much deeper than the Solnhofen lagoons. The flora of these islands was adapted to these dry conditions and consisted mostly of low (3 m ) shrubs. Contrary to reconstructions of Archaeopteryx climbing large trees, these seem to have been mostly absent from the islands; few trunks have been found in the sediments and fossilized tree pollen is also absent.

The lifestyle of Archaeopteryx is difficult to reconstruct and there are several theories regarding it. Some researchers suggest that it was primarily adapted to life on the ground, while other researchers suggest that it was principally arboreal. The absence of trees does not preclude Archaeopteryx from an arboreal lifestyle as several species of extant bird live exclusively in low shrubs. Various aspects of the morphology of Archaeopteryx point to either an arboreal or ground existence, including the length of its legs and the elongation in its feet; some authorities consider it likely to have been a generalist capable of feeding in both shrubs and open ground, as well as alongside the shores of the lagoon. It most likely hunted small prey, seizing it with its jaws if it was small enough, or with its claws if it was larger.