These are not the Paleogene Penguins you are Looking for

New late Eocene and Oligocene remains of the flightless, penguin-like plotopterids (Aves, Plotopteridae) from western Washington State, U.S.A.

Authors:

Mayr et al

Abstract:

We describe new plotopterids (Aves, Plotopteridae) from late Eocene and Oligocene strata in western Washington State, U.S.A. The specimens belong to four new species of these flightless, wing-propelled seabirds, three of which are named and assigned to two new supraspecific taxa, Olympidytes, gen. nov., and Klallamornis, gen. nov. We confirm previous observations on a high diversity of plotopterids in the Paleogene of North America, but because the fossils are from different formations, it remains elusive how many of the six currently recognized species from western Washington actually coexisted. Tonsala, the only previously described plotopterid taxon from the Olympic Peninsula, is likely to occupy a more basal phylogenetic position than the other plotopterids of this geographic area. Olympidytes and Klallamornis may be successive sister taxa of Copepteryx and Hokkaidornis from the late Oligocene of Japan, but a determination of the exact affinities of the new taxa requires the discovery of further fossils. Notably, the geochronologically youngest plotopterid, the early Miocene Plotopterum, differs from earlier taxa in plesiomorphic features and is here considered to be among the phylogenetically most basal plotopterids. The late Eocene basal Phocavis likewise temporally overlaps with more derived plotopterid taxa. The coexistence of basal and more derived plotopterids in the late Eocene may indicate a rapid evolution of plotopterids towards the late Eocene. The factors that allowed the persistence of basal taxa into the Miocene remain, however, elusive, and so are those that triggered the evolution of wing-propelled diving in these highly specialized birds.

Predictable evolution toward flightlessness in volant island birds

Predictable evolution toward flightlessness in volant island birds

Authors:

Wright et al

Abstract:

Birds are prolific colonists of islands, where they readily evolve distinct forms. Identifying predictable, directional patterns of evolutionary change in island birds, however, has proved challenging. The “island rule” predicts that island species evolve toward intermediate sizes, but its general applicability to birds is questionable. However, convergent evolution has clearly occurred in the island bird lineages that have undergone transitions to secondary flightlessness, a process involving drastic reduction of the flight muscles and enlargement of the hindlimbs. Here, we investigated whether volant island bird populations tend to change shape in a way that converges subtly on the flightless form. We found that island bird species have evolved smaller flight muscles than their continental relatives. Furthermore, in 366 populations of Caribbean and Pacific birds, smaller flight muscles and longer legs evolved in response to increasing insularity and, strikingly, the scarcity of avian and mammalian predators. On smaller islands with fewer predators, birds exhibited shifts in investment from forelimbs to hindlimbs that were qualitatively similar to anatomical rearrangements observed in flightless birds. These findings suggest that island bird populations tend to evolve on a trajectory toward flightlessness, even if most remain volant. This pattern was consistent across nine families and four orders that vary in lifestyle, foraging behavior, flight style, and body size. These predictable shifts in avian morphology may reduce the physical capacity for escape via flight and diminish the potential for small-island taxa to diversify via dispersal.

New Remains of Late Cretaceous Giant Bird Gargantuavis philoinos Found in France

New remains of the giant bird Gargantuavis philoinos from the Late Cretaceous of Provence (south-eastern France)

Authors:

Buffetaut et al

Abstract:

Two incomplete pelves of the giant bird Gargantuavis philoinos are described from Late Cretaceous deposits at Fox-Amphoux (Var, south-eastern France). They consist of synsacra with attached parts of the ilia. One of them has undergone considerable dorsoventral compression, which makes it very similar in appearance to the holotype pelvis of Gargantuavis philoinos from Campagne-sur-Aude (Aude, southern France). The second specimen has suffered some lateral distortion but is uncrushed dorsoventrally. Because of this, its avians characters (including an arched synsacrum and widespread pneumatisation) are especially clear. These new specimens confirm the avian nature of Gargantuavis and reveal new details about its pelvic anatomy, but provide little new evidence about its systematic position within Aves. The geographical distribution and general rarity of Gargantuavis are discussed.

Ilbandornis woodburnei: A New Species of Oligocene/Miocene Flightless Mihirung

The extinct flightless mihirungs (Aves, Dromornithidae): cranial anatomy, a new species, and assessment of Oligo-Miocene lineage diversity

Authors:

Worthy et al

Abstract:

Giant flightless fowl (Aves, Dromornithidae) similar to the Northern Hemisphere gastornithids and weighing up to 350–650 kg evolved on Gondwana and existed in what is now Australia from the Eocene to the late Quaternary. Understanding cranial morphology of dromornithids has until now been based almost wholly on species of Dromornis, with that of species in three other genera either previously unknown or very fragmentary. Here we rectify this deficiency and describe a well-preserved cranium from the middle Miocene Bullock Creek Local Fauna referred to Ilbandornis woodburnei, rich, fragmentary crania, quadrates, pterygoids, and mandibles for the Oligo-Miocene Barawertornis tedfordi Rich, and additional material of the species of Ilbandornis. The morphological similarity of this cranial material suggests that the emu-sized B. tedfordi is a smaller precursor to and differs little from species of Ilbandornis. Dromornis murrayi, n. sp., from late Oligocene–Early Miocene sites at Riversleigh, based on cranial and postcranial elements, is the oldest and smallest species in its genus. Placed in the context of other data, these observations suggest that the dromornithids comprised only two lineages throughout the Oligo-Miocene. The Barawertornis-Ilbandornis lineage attained maximum diversity in the middle Miocene Bullock Creek and late Miocene Alcoota local faunas (LF), with two species in each, but the Dromornis lineage seems to have been monotypic throughout its temporal range. The low diversity of these giant galloanseres in Australia mirrors that of the giant herbivorous ratites (ostriches and kin), which similarly have low diversity where they coevolved with diverse mammalian faunas.

Palaeotis: A Flightless Bird From Eocene Paleogene Europe may NOT be a Ratite

The middle Eocene European “ratite” Palaeotis (Aves, Palaeognathae) restudied once more

Author:

Mayr

Abstract:

Palaeotis weigelti is a flightless, “ratite”-like palaeognathous bird, which occurs in the Middle Eocene of the German fossil sites Messel and the Geisel Valley. The species is known from several specimens, most of which are, however, very fragmentary or poorly preserved. Its phylogenetic affinities are controversial, with earlier authors especially considering close affinities to Struthionidae and Rheidae, and some skeletal features were only briefly described. Moreover, recent molecular analyses congruently indicate that a “ratite” morphology evolved multiple times within palaeognathous birds. The skeletal morphology and phylogenetic affinities of Palaeotis are therefore reanalyzed, and the taxon is subjected to a phylogenetic analysis based on one of the most comprehensive published data sets for palaeognathous birds. In addition to the primary analysis, further analyses were run that were constrained to a backbone topology reflecting the results of sequence-based studies. In none of these analyses was a well-supported placement of Palaeotis obtained, and it is concluded that current data do not convincingly resolve the affinities of this taxon. Palatal morphology of Palaeotis most closely resembles that of lithornithids, another group of palaeognathous birds from the Eocene of the Northern Hemisphere, and there remains a possibility that the “ratite” features of Palaeotis evolved independently from those of the extant taxa.

The Giant Flightless Birds of Paleogene Europe

Stratigraphic distribution of large flightless birds in the Palaeogene of Europe and its palaeobiological and palaeogeographical implications

Authors:

Buffetaut et al

Abstract:

The stratigraphic distribution of the three main groups of large flightless birds known from the Palaeogene of Europe, Gastornithidae, Phorusrhacidae and Ratitae, is reviewed. The huge, herbivorous gastornithids, represented by the single genus Gastornis, are known from the Selandian (Middle Palaeocene) to the late Lutetian (Middle Eocene), being recorded from reference levels MP5 to MP13. The carnivorous phorusrhacids are represented by a single species, Eleutherornis cotei, from the late Lutetian (MP14, late Middle Eocene). The ratites have a patchy distribution, being represented by two species of moderate size, Remiornis heberti from the Thanetian (MP6, Late Palaeocene) and Palaeotis weigelti from the Lutetian (MP11 to MP13, Middle Eocene). The stratigraphic distributions of large eggs referred to gastornithids in the Late Palaeocene and Early Eocene of southern Europe and the occurrence of enigmatic large avian footprints in the Late Eocene of France are discussed. Whereas gastornithids and ratites co-existed in both the Palaeocene and the Middle Eocene, phorusrhacids seem to have been the only large ground birds in Europe at the end of the Middle Eocene. The palaeobiogeographical and evolutionary implications of the stratigraphic distributions of those groups of large birds in Europe are discussed. As Gastornis first appears in North America and in Asia in the Early Eocene, it is likely that gastornithids originated in Europe and later spread to other land masses during a dispersal event close to the Palaeocene–Eocene boundary. Prior to that, gastornithids evolved on the European “island continent”, where they were the largest terrestrial tetrapods during the Palaeocene. Gastornithids do not seem to have been significantly affected by the PETM. Ratitae have a more patchy record and relationships between Remiornis and Palaeotis remain unclear. Nevertheless, those European forms are among the earliest known ratites and this should not be overlooked in discussions of ratite evolution and palaeobiogeography. Phorusrhacids appear to have been present in Europe for only a short time and are interpreted as the result of dispersal from Africa followed by local extinction.

Gastornis: A Giant Flightless Bird Found in Ypresian Eocene Paleogene Europe (as well as NorAm)

The birds (Aves) from the Early Eocene of La Borie, southern France

Authors:

Bourdon et al

Abstract:

The Early Eocene locality of La Borie is located in the village of Saint-Papoul, in southern France. These Eocene fluvio-lacustrine clay deposits have yielded numerous vertebrate remains. Mammalian taxa found in the fossiliferous levels indicate an age near the reference level MP 8–9, which corresponds to the middle Ypresian, Lower Eocene. Here we provide a detailed description of the avian remains that were preliminarily reported in a recent study of the vertebrate fauna from La Borie. A maxilla, a quadrate, cervical vertebrae, a femur and two tibiotarsi are assigned to the giant ground bird Gastornis parisiensis Hébert, 1855 (Gastornithidae). These new avian remains add to the fossil record of Gastornis, which is known from the Upper Paleocene to Middle Eocene of Europe, Early Eocene of Asia, and Early Eocene of North America. Gastornis parisiensis differs from the North American Gastornis giganteus (Cope, 1876) in several features, including the more ventral position of the external nares and the slender orbital process of quadrate. Two tibiotarsi and one tarsometatarsus are assigned to a new genus and species of Geranoididae, Galligeranoides boriensis gen. nov, sp. nov. So far, this family was known only from the Early and Middle Eocene of North America. The fossils from La Borie constitute the first record of the Geranoididae in Europe. We show that Gastornis coexisted with the Geranoididae in the Lower Eocene of both Europe (La Borie) and North America (Willwood formation). The presence of Geranoididae and the large flightless bird Gastornis on either side of the present-day North Atlantic provides further evidence that a high-latitude land connection existed between Europe and North America in the Early Eocene.

Was Archaeopteryx in the Process of Becoming the Earliest Known Flightless Bird?

Although it has long been debated whether the proto-bird Archaeopteryx was able to actually fly or merely evolving toward that ability, to date nobody had yet seriously suggested that it could have been instead in the midst of losing its ability to fly. But that is precisely what Michael Habib, a biologist at the University of Southern California proposed last week to a packed hall at the annual meeting of the Society of Vertebrate Paleontology in Los Angeles.

With the skeleton of a dinosaur and the feathers of a bird, Archaeopteryx has long been hailed as marking the transition from dinosaurs to birds.

The idea that it was instead evolving to lose its flight and becoming flightless again, or 'secondarily flightless', occurred to Habib while he was calculating limb ratios and degrees of feather symmetry in Archaeopteryx, and comparing the values to those of living birds, to better understand its flying ability. In doing so, he found that the creature's traits were surprisingly similar to those of modern flightless birds such as rails and grebes that frequently dwell on islands.

“We know Archaeopteryx was living on an archipelago during the Jurassic. And with its feathers and bones looking so much like modern flightless island birds, it just makes me wonder,” says Habib.

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