Alexander Lukeneder

Bio: Alexander Lukeneder is an academic researcher from Naturhistorisches Museum. The author has contributed to research in topics: Cretaceous & Ammonite. The author has an hindex of 18, co-authored 76 publications receiving 1303 citations. Previous affiliations of Alexander Lukeneder include American Museum of Natural History & University of Vienna.

Pelagic palaeoecology: the importance of recent constraints on ammonoid palaeobiology and life history

Abstract: A review of fossil evidence supports a pelagic mode of life (in the water column) of ammonoids, but they may have spent their life close to the seabottom (demersal), planktonically, or nektonically depending upon the ontogenetic stage and taxon. There are good indications for a planktonic mode of life of ammonoid hatchlings, but a broad range of reproductive strategies might have existed (egg-laying, fecundity). Isotope and biogeographical studies indicate that some forms migrated or swam for considerable distances, whereas others may have been primarily transported by oceanic currents during early and/or late ontogeny. Diverse ammonoid habitats are also supported by evidence from predator–prey relationships derived from characteristic injuries and exceptional fossil finds, which indicate chiefly predatory or scavenging lifestyles. Sublethal injuries preserved in some ammonoid shells, as well as rare stomach and coprolite contents, provide evidence of predation by other cephalopods, arthropods and various jawed vertebrates. Various lines of evidence suggest that different groups of ammonoids had quite different ecologies, but shell shape alone can only give upper constraints on ammonoid capabilities, a matter that needs to be considered when interpreting their diversity and evolutionary history.

The Cretaceous Period

Abstract: The breakup of the former Pangea supercontinent culminated in the modern drifting continents. Increased rifting caused the establishment of the Atlantic Ocean in the middle Jurassic and significant widening in Cretaceous. An explosion of calcareous nannoplankton and foraminifers in the warm seas created massive chalk deposits. A surge in submarine volcanic activity enhanced supergreenhouse conditions in the middle Cretaceous with high CO2 concentrations. Angiosperm plants bloomed on the dinosaur-dominated land during late Cretaceous. The Cretaceous dramatically ended with an asteroid impact, which resulted in a mass extinction.

The Cretaceous Period

Abstract: IN NATURE of Jan. 19, a letter appeared from Prof. Wyville Thomson defending the expressions, “we are still living in the Cretaceous epoch,” “the chalk is being formed at present in the bed of the Atlantic.” When first this announcement was made, it was followed up by various strong comments implying that the similarity of the Atlantic mud to the chalk in lithological character, and in many of the imbedded organisms* “would seem to unsettle much that has generally been accredited to geological science,” would, in fact, revolutionise geological classification.