Testing models of macroevolution, and especially the sufficiency of microevolutionary processes, requires good collaboration between molecular biologists and paleontologists. We report such a test for events around the Late Cretaceous by describing the earliest penguin fossils, analyzing complete mitochondrial genomes from an albatross, a petrel, and a loon, and describe the gradual decline of pterosaurs at the same time modern birds radiate. The penguin fossils comprise four naturally associated skeletons from the New Zealand Waipara Greensand, a Paleocene (early Tertiary) formation just above a well-known Cretaceous/Tertiary boundary site. The fossils, in a new genus (Waimanu), provide a lower estimate of 61-62 Ma for the divergence between penguins and other birds and thus establish a reliable calibration point for avian evolution. Combining fossil calibration points, DNA sequences, maximum likelihood, and Bayesian analysis, the penguin calibrations imply a radiation of modern (crown group) birds in the Late Cretaceous. This includes a conservative estimate that modern sea and shorebird lineages diverged at least by the Late Cretaceous about 74 +/- 3 Ma (Campanian). It is clear that modern birds from at least the latest Cretaceous lived at the same time as archaic birds including Hesperornis, Ichthyornis, and the diverse Enantiornithiformes. Pterosaurs, which also coexisted with early crown birds, show notable changes through the Late Cretaceous. There was a decrease in taxonomic diversity, and small- to medium-sized species disappeared well before the end of the Cretaceous. A simple reading of the fossil record might suggest competitive interactions with birds, but much more needs to be understood about pterosaur life histories. Additional fossils and molecular data are still required to help understand the role of biotic interactions in the evolution of Late Cretaceous birds and thus to test that the mechanisms of microevolution are sufficient to explain macroevolution.

Early Penguin Fossils, Plus Mitochondrial Genomes, Calibrate Avian Evolution

Due to regional glacio-isostatic uplift of land during the Holocene period, a large number of penguin populations from several rookeries began to nest on the newly formed beaches and emerged rocks, leaving previously colonized higher cliffs. Chronology and extent of raised beaches, lichenometric age estimation of Usnea antarctica and radiocarbon-dating of guano and subfossil penguin bones in the abandoned nesting sites suggest the progress of the downward movement of many rookeries about 2500 years ago, accelerated during the last millennium, when wide bands of 4 to 6 m raised beaches were formed. Patterns of relic ornithogenic soil formation in the abandoned rookeries (focussed on leaching, erosion processes and humus horizon creation), as well as the succession of vegetation in the age sequence of abandoned nesting sites, were investigated in detail at Stranger Point, King George Island. The chemical composition of Deschampsia antarctica growing in the area of active, abandoned rookeries and in control sites provides direct and indirect evidence of current and past ornithogenic manuring on nutrition of vegetation.

Formation of abandoned penguin rookery ecosystems in the maritime Antarctic

The phylogeny of the living and fossil Sphenisciformes (penguins)

Background
Debate regarding the monophyly and relationships of the avian order Pelecaniformes represents a classic example of discord between morphological and molecular estimates of phylogeny. This lack of consensus hampers interpretation of the group's fossil record, which has major implications for understanding patterns of character evolution (e.g., the evolution of wing-propelled diving) and temporal diversification (e.g., the origins of modern families). Relationships of the Pelecaniformes were inferred through parsimony analyses of an osteological dataset encompassing 59 taxa and 464 characters. The relationships of the Plotopteridae, an extinct family of wing-propelled divers, and several other fossil pelecaniforms (Limnofregata, Prophaethon, Lithoptila, ?Borvocarbo stoeffelensis) were also assessed. The antiquity of these taxa and their purported status as stem members of extant families makes them valuable for studies of higher-level avian diversification.

Phylogenetic analysis of pelecaniformes (aves) based on osteological data: implications for waterbird phylogeny and fossil calibration studies.

One of the most significant global climatic events in the Cenozoic was the transi− tion from greenhouse to icehouse conditions in Antarctica. Tectonic evolution of the region and gradual cooling at the end of Eocene led to the first appearance of ice sheets at the Eocene/Oligocene boundary (ca. 34 Ma). Here we report geological record of mountain gla− ciers that preceded major ice sheet formation in Antarctica. A terrestrial, valley−type tillite up to 65 metres thick was revealed between two basaltic lava sequences in the Eocene- Oligocene Point Thomas Formation at Herve Cove - Breccia Crag in Admiralty Bay, King George Island, South Shetland Islands. K−Ar dating of the lavas suggests the age of the gla− ciation at 45-41 Ma (Middle Eocene). It is the oldest Cenozoic record of alpine glaciers in West Antarctica, providing insight into the onset of glaciation of the Antarctic Peninsula and South Shetland Islands. Key wor ds: Antarctica, King George Island, Eocene, mountain glaciers.

First Cenozoic glaciers in West Antarctica

Eocene penguin remains from Seymour Island (Antarctica) are so far the old− est−known record of extinct Sphenisciformes. Rich Argentine and Polish collections of pen− guin bones from the La Meseta Formation are taxonomically revised on tarsometatarsal morphology. Two genera and four species are erected: Mesetaornis polaris gen. et sp. n., Marambiornis exilis gen. et sp. n., Delphinornis arctowskii sp. n. and D. gracilis sp. n. Moreover, the diagnoses of already described species: Anthropornis nordenskjoeldi, A. grandis, Palaeeudyptes klekowskii, P. gunnari, Archaeospheniscus wimani and Delphi− nornis larseni are revised as well. Gradual cooling of climate, changes of environment and trophic relationships, that lasted several millions years, were most probably responsible for the intense speciation and taxonomic diversification of the Middle-Late Eocene La Meseta penguins.

R.A. Del Valle

Papers

Taxonomic revision of Eocene Antarctic penguins based on tarsometatarsal morphology

Numbers of Adelie penguins breeding at Hope Bay and Seymour Island rookeries (West Antarctica) in 1985