Combined phylogenetic analysis of a new North American fossil species confirms widespread Eocene distribution for stem rollers (Aves,Coracii)

We report a nearly complete skeleton of a new species of stem roller (Aves, Coracii) from the early Eocene Green River Formation of North America. The new species is most closely related to two species‐depauperate lineages, Coraciidae (rollers) and Brachypteraciidae (ground rollers), that form a monophyletic crown clade (Coracioidea) with an exclusively Old World extant distribution. Phylogenetic analysis utilizing a matrix of 133 morphological characters and sequence data from three genes (RAG‐1, c‐myc, and ND2) identifies the new species as a stem member of the Coracii more closely related to the crown clade than the only previously identified New World taxon, Primobucco mcgrewi. The phylogenetic placement of the new species and Primobucco mcgrewiindicates a widespread northern hemisphere distribution in the Eocene with subsequent restriction to Africa, Madagascar, Australia, and temperate to tropical parts of Europe and Asia. It provides evidence of further ecological diversity in early stem Coracii and convergence on crown morphologies. The new species contributes to mounting evidence that extant distributions for major avian subclades may be of comparatively recent origin. Further late Palaeogene sampling is needed to elucidate potential drivers for shifting avian distributions and disappearance of Coracii from North America. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 157 , 586–611.     

A reassessment of Eocene parrotlike fossils indicates a previously undetected radiation of zygodactyl stem group representatives of passerines (Passeriformes)

In the past years, various Eocene fossil birds were described as stem group representatives of the zygodactyl Psittaciformes (parrots). These birds show quite disparate morphologies, which cast some doubt on the correct assignment of all of them to the psittaciform stem group. A reassessment of their affinities is further needed, because it was recently proposed that among extant birds, Psittaciformes and Passeriformes (passerines) form a clade and that passerines possibly derived from a zygodactyl ancestor. Here, phylogenetic analyses are performed, which for the first time also include representatives of the Zygodactylidae, the extinct zygodactyl sister taxon of the Passeriformes. The early Eocene Psittacopes was originally described as a stem group representative of Psittaciformes. However, none of the present analyses supported psittaciform affinities for Psittacopes and instead recovered this taxon in a clade together with zygodactylids and passerines. Also part of this clade are the early Eocene taxa Pumiliornis and Morsoravis, and it is detailed that Psittacopes and the long‐beaked and presumably nectarivorous Pumiliornis, with which it has not yet been compared, are very similar in their postcranial osteology. The present analysis corroborates the hypothesis of a zygodactyl stem species of passerines. To account for these results, Psittacopes is here assigned to a new higher‐level taxon and a new name is also introduced for the clade including Zygodactylidae and Passeriformes.     

A South American snake lineage from the Eocene Greenhouse of North America and a reappraisal of the fossil record of “anilioid” snakes

“Anilioidea” is a likely paraphyletic assemblage of pipe snakes that includes extant Aniliidae from equatorial South America, Uropeltoidea from South and Southeast Asia, and a fossil record that consists primarily of isolated precloacal vertebrae ranging from the earliest Late Cretaceous and includes geographic distributions in North America, South America, Europe, and Africa. Articulated precloacal vertebrae from the middle Eocene Bridger Formation of Wyoming, attributed to Borealilysia nov. gen., represent an unambiguous North American aniliid record and prompts a reconsideration of described pipe snakes and their resultant biogeographic histories. On the basis of vertebral apomorphies, the vast majority of reported fossils cannot be assigned to “Anilioidea”. Instead, most records represent stem taxa and macrostomatans erroneously assigned to anilioids on the basis of generalized features associated with fossoriality. A revised fossil record demonstrates that the only extralimital distributions of fossil “anilioids” consist of the North American aniliid record, and there is no unambiguous fossil record of Old World taxa. The occurrence of aniliids in the mid-high latitudes of the late early Eocene of North America is consistent with histories of northward shifts in equatorial ecosystems during the early Paleogene Greenhouse.     

Early Eocene fossil illuminates the ancestral (diurnal) ecomorphology of owls and documents a mosaic evolution of the strigiform body plan

We describe a partial skeleton of a fossil owl (Strigiformes) from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). The holotype of Ypresiglaux michaeldanielsi, gen. et sp. nov. is one of the most complete specimens of a Palaeogene owl and elucidates the poorly known ecomorphology of stem group Strigiformes. Whereas most of the postcranial bones show the characteristic strigiform morphology, the new species exhibits plesiomorphic features of the skull and cervical vertebrae that differ distinctly from extant owls. A well-developed supraorbital process of the lacrimal bone suggests that the eyes were not as greatly enlarged and forward-facing as in extant owls. A plesiomorphic quadrate morphology indicates differences in the otic region, and a proportionally longer axis suggests that the fossil species was not able to rotate its head to the degree found in crown group Strigiformes. Therefore, the fossil documents a mosaic evolution of the strigiform body plan, with owls developing raptorial adaptations before specializations of the visual and acoustic systems evolved. Because the latter relate to a crespuscular or nocturnal activity pattern, we hypothesize that Ypresiglaux was diurnal. Nocturnality in owls may have evolved in response to the emergence of evolutionary opportunities, which enabled owls to exploit new ecological niches, or owls may have been driven into nocturnal habits by ecological competition.     

New fossil materials of the earliest new world monkey, Branisella boliviana, and the problem of platyrrhine origins

Branisella boliviana, from the Late Oligocene of Salla, Bolivia, is the oldest fossil platyrrhine monkey discovered. To date, several fossil specimens of Branisella have been obtained, but most of them are fragmentary dentitions, so the animals craniodental morphology is still obscure. During the 1996 field season a pair of upper and lower jaw fragments and another nearly complete mandible were recovered. These new fossil materials reveal the following morphological features in Branisella: 1) P(2) is much smaller than P(3,4), whereas P(2) is relatively small but probably sexually dimorphic; 2) the zygomatic arch protrudes smoothly posterolaterally from the maxillary bone, as in extant Callicebus; 3) the mandibular arcade is nearly V-shaped and the symphysial angle, which is formed by the horizontal plane and the anterior face of mandibular symphysis, is about 40 degrees, i.e., it neither leans as far anteriorly as in callitrichines nor does it stand as vertically as Cebus; 4) upper and lower molars wore down rapidly in life, suggesting a herbivorous diet and the possibility of terrestriality; and 5) dental eruptive sequence is the same as in extant Aotus. As a whole, the dentition of Branisella is very similar to that of Proteopithecus from the Late Eocene of Fayum, Egypt, except in the lower canine morphology, suggesting a close phyletic relationship between them. The origin and early diversification of platyrrhine monkeys might have occurred on the African continent before crossing the Atlantic Ocean.     

Diets of fossil primates from the Fayum Depression of Egypt: a quantitative analysis of molar shearing

Over the last 90 years, Eocene and Oligocene aged sediments in the Fayum Depression of Egypt have yielded at least 17 genera of fossil primates. However, of this diverse sample the diets of only four early Oligocene anthropoid genera have been previously studied using quantitative methods. Here we present dietary assessments for 11 additional Fayum primate genera based on the analysis of body mass and molar shearing crest development. These studies reveal that all late Eocene Fayum anthropoids were probably frugivorous despite marked subfamilial differences in dental morphology. By contrast, late Eocene Fayum prosimians demonstrated remarkable dietary diversity, including specialized insectivory (Anchomomys), generalized frugivory (Plesiopithecus), frugivory+insectivory (Wadilemur), and strict folivory (Aframonius). This evidence that sympatric prosimians and early anthropoids jointly occupied frugivorous niches during the late Eocene reinforces the hypothesis that changes in diet did not form the primary ecological impetus for the origin of the Anthropoidea. Early Oligocene Fayum localities differ from late Eocene Fayum localities in lacking large-bodied frugivorous and folivorous prosimians, and may document the first appearance of primate communities with trophic structures like those of extant primate communities in continental Africa. A similar change in primate community structure during the Eocene-Oligocene transition is not evident in the Asian fossil record. Putative large anthropoids from the Eocene of Asia, such as Amphipithecus mogaungensis, Pondaungia cotteri, and Siamopithecus eocaenus, share with early Oligocene Fayum anthropoids derived features of molar anatomy related to an emphasis on crushing and grinding during mastication. However, these dental specializations are not seen in late Eocene Fayum anthropoids that are broadly ancestral to the later-occurring anthropoids of the Fayum's upper sequence. This lack of resemblance to undisputed Eocene African anthropoids suggests that the "progressive" anthropoid-like dental features of some large-bodied Eocene Asian primates may be the result of dietary convergence rather than close phyletic affinity with the Anthropoidea.     

New specimens of the early Eocene bird Vastanavis and the interrelationships of stem group Psittaciformes

We describe new skeletal elements of Vastanavis from the early Eocene Cambay Shale Formation of western India, including a small coracoid that represents an unnamed new species, and comment on the relationships between this avian taxon and the recently described Avolatavis from the early Eocene Green River Formation in North America. Like the previously described ones, the new Vastanavis bones resemble those of the late Eocene Quercypsittidae, thus strengthening psittaciform affinities of the Indian taxon. Vastanavis differs from Avolatavis in the presence of a crista medianoplantaris on the tarsometatarsus and in claw morphology, but a fossil from the early Eocene London Clay, which was previously assigned to Vastanavidae, closely resembles Avolatavis in these features and all other osteological aspects. We show that most branches in a recent phylogeny of stem group Psittaciformes collapse after modification of a single erroneous character scoring for Vastanavis. We further describe a morphologically distinctive distal humerus of a small bird resembling the stem group nyctibiid Paraprefica, which was discovered in the most recent excavation in Vastan Lignite Mine.     

Seed morphology of modern and fossil Ampelocissus (Vitaceae) and implications for phytogeography

Seeds are useful in distinguishing among extant genera of Vitaceae and provide a good basis for interpretation of fossil remains in reconstructing the evolutionary and phytogeographic history of this putatively basal Rosid family. Seeds of Ampelocissus s.l. including Pterisanthes and Nothocissus are distinguished from those of all other vitaceous genera by long, parallel ventral infolds and a centrally positioned oval chalazal scar. Principal component analysis facilitates recognition of four Ampelocissus s.l. seed morphotypes differentiated by dorsiventral thickness, width of ventral infolds, chalazal depth, and degree of dorsal surface rugosity. While these intergrade, their end-member morphologies are distinctive and coincide well with inflorescence morphology, extant geographic distribution, and ecology. Seven fossil morphospecies are recognized. Ampelocissus parvisemina sp. n. (Paleocene of North Dakota; Eocene of Oregon) and A. auriforma Manchester (Eocene of Oregon) resemble extant Central American species; A. bravoi Berry (Eocene of Peru) is similar to one group of Old World extant species; and A. parachandleri sp. n. (Eocene of Oregon) and the three European fossil species A. chandleri (Kirchheimer) comb. n., A. lobatum (Chandler) comb. n., and A. wildei sp. n. (Eocene to Miocene) resemble another group of extant Old World Ampelocissus. All these fossils occur outside the present geographic range of the genus, reflecting warmer climates and former intercontinental links.     

Fossil penguin (Aves: Sphenisciformes) cranial material from the Eocene of Seymour Island (Antarctica)

Our knowledge of the cranial morphology of early penguins remains poor, particularly for Paleogene taxa. This paper describes a partial penguin skull and additional isolated cranial elements from the Eocene La Meseta Formation of Seymour Island, Antarctica. These specimens cannot be assigned to named taxa at present, but there is a strong possibility they belong to La Meseta penguins known only from postcranial elements. The skull shares extensive dorsal development of the temporal fossae with extant and fossil Spheniscus and the fossil penguins Paraptenodytes and Marplesornis, indicating the adductor complex was powerful in early penguins. Partial mandibles belonging to a much larger penguin are similar to Paraptenodytes and differ from all living penguins in the lack of a hooked medial process of the articular and the presence of a foramen anterior to the mandibular cotyles. Given the rarity of penguin cranial remains, these specimens provide important new insight into early penguin evolution.     

Late Oligocene mousebird converges on parrots in skull morphology

A new fossil stem group representative of Coliiformes (mousebirds) with a remarkable skull morphology is described from the late Oligocene of Germany. Oligocolius psittacocephalon sp. nov. for the first time preserves the skull of a post‐Eocene fossil mousebird. This exhibits a combination of skull features unknown from any other bird and converges on the skull of parrots in that the beak is separated from the cranium by a marked nasofrontal hinge and in that the interorbital part of the frontal bones is very wide. In addition, the mandible of the new species exhibits long retroarticular processes, which are unexpected because unlike in other coliiform birds exhibiting this feature, the short beak was probably not used for probing in substrate. It is hypothesized that the retroarticular processes of O. psittacocephalon instead served for a particular wide and forceful opening of the beak. Eight large fruit stones are situated in the area of the digestive tract of the new species. Preservation of most of these in a well‐delimited cluster in the region of the upper oesophagus suggests that, unlike in modern mousebirds, O. psittacocephalon had a crop. The new fossil shows that late Oligocene European stem group Coliiformes significantly differed from their extant relatives in morphology and probably also in feeding ecology.     

A specimen of Eocuculus Chandler, 1999 (Aves, ? Cuculidae) from the early Oligocene of France

A postcranial skeleton of a small bird from the early Oligocene locality Pichovet in Southern France is described and identified as Eocuculus cf. cherpinae Chandler, 1999. It is the second fossil record of Eocuculus which was hitherto known from a postcranial skeleton from the late Eocene of North America only. Although Eocuculus shares some derived similarities with Cuculidae (cuckoos), it distinctly differs in a number of osteological features from crown group members of this taxon. If future, more complete skeletons prove its cuculiform affinities, Eocuculus is a stem lineage representative of this taxon and not within the crown group. Recognition of Eocuculus in the early Oligocene of France provides evidence for the presence of an extinct late Eocene/early Oligocene avian taxon with an intercontinental Northern Hemisphere distribution.     

New spiders in Upper Cretaceous amber from New Jersey in the American Museum of Natural History (Arthropoda: Araneae)

The oldest described fossils of the extant spider family Araneidae (Araneinae; gen. et sp. indet.), the extant genus Orchestina (Oonopidae; O. sp. indet.) and the new fossil genus Palaeosegestria (Segestriidae; P. lutzzii gen. et sp. nov.) are presented from Upper Cretaceous amber of New Jersey. The known fossil range of the extant family Araneidae is extended approximately 50 myr from the previously oldest described araneid from the Middle Eocene oil shales of the Messel pit in Hesse, Germany. The fossil range of the extant genus Orchestina is also extended 50 myr from the previously oldest described specimen in Eocene Baltic amber.     

Oldest known Eucalyptus macrofossils are from South America

The evolutionary history of Eucalyptus and the eucalypts, the larger clade of seven genera including Eucalyptus that today have a natural distribution almost exclusively in Australasia, is poorly documented from the fossil record. Little physical evidence exists bearing on the ancient geographical distributions or morphologies of plants within the clade. Herein, we introduce fossil material of Eucalyptus from the early Eocene (ca. 51.9 Ma) Laguna del Hunco paleoflora of Chubut Province, Argentina; specimens include multiple leaves, infructescences, and dispersed capsules, several flower buds, and a single flower. Morphological similarities that relate the fossils to extant eucalypts include leaf shape, venation, and epidermal oil glands; infructescence structure; valvate capsulate fruits; and operculate flower buds. The presence of a staminophore scar on the fruits links them to Eucalyptus, and the presence of a transverse scar on the flower buds indicates a relationship to Eucalyptus subgenus Symphyomyrtus. Phylogenetic analyses of morphological data alone and combined with aligned sequence data from a prior study including 16 extant eucalypts, one outgroup, and a terminal representing the fossils indicate that the fossils are nested within Eucalyptus. These are the only illustrated Eucalyptus fossils that are definitively Eocene in age, and the only conclusively identified extant or fossil eucalypts naturally occurring outside of Australasia and adjacent Mindanao. Thus, these fossils indicate that the evolution of the eucalypt group is not constrained to a single region. Moreover, they strengthen the taxonomic connections between the Laguna del Hunco paleoflora and extant subtropical and tropical Australasia, one of the three major ecologic-geographic elements of the Laguna del Hunco paleoflora. The age and affinities of the fossils also indicate that Eucalyptus subgenus Symphyomyrtus is older than previously supposed. Paleoecological data indicate that the Patagonian Eucalyptus dominated volcanically disturbed areas adjacent to standing rainforest surrounding an Eocene caldera lake.     

Avian higher level biogeography: Southern Hemispheric origins or Southern Hemispheric relicts?

A recent analysis of a comprehensive phylogenetic data set suggested Southern Hemispheric origins for various higher level taxa of neornithine (crown group) birds. These results contrast with hypotheses derived from the fossil record, with the occurrence of successively branching stem group representatives of many “Southern Hemispheric” bird groups in the early Cenozoic of Europe and North America suggesting relict extant distributions. However, a selective consideration of the fossil record and the merging of extant ranges may have resulted in a skewed picture of the past biogeographical history of birds. For future studies, it is proposed that multiple taxa of successively branching Northern Hemispheric stem group representatives are considered to narrow down the ancestral areas of the crown group representatives.     

Melanosome diversity and convergence in the evolution of iridescent avian feathers—Implications for paleocolor reconstruction

Some of the most varied colors in the natural world are created by iridescent nanostructures in bird feathers, formed by layers of melanin‐containing melanosomes. The morphology of melanosomes in iridescent feathers is known to vary, but the extent of this diversity, and when it evolved, is unknown. We use scanning electron microscopy to quantify the diversity of melanosome morphology in iridescent feathers from 97 extant bird species, covering 11 orders. In addition, we assess melanosome morphology in two Eocene birds, which are the stem lineages of groups that respectively exhibit hollow and flat melanosomes today. We find that iridescent feathers contain the most varied melanosome morphologies of all types of bird coloration sampled to date. Using our extended dataset, we predict iridescence in an early Eocene trogon (cf. Primotrogon) but not in the early Eocene swift Scaniacypselus, and neither exhibit the derived melanosome morphologies seen in their modern relatives. Our findings confirm that iridescence is a labile trait that has evolved convergently in several lineages extending down to paravian theropods. The dataset provides a framework to detect iridescence with more confidence in fossil taxa based on melanosome morphology.     

CHATTAWAYA (STERCULIACEAE): A NEW GENUS OF WOOD FROM THE EOCENE OF OREGON AND ITS IMPLICATIONS FOR XYLEM EVOLUTION OF THE EXTANT GENUS PTEROSPERMUM

A new sterculiaceous wood, Chattawaya paliformis gen. et sp. n., was collected from a Middle Eocene locality in the type area of the Clamo Formation of north central Oregon. The wood differs from all known extant woods in having very large and irregularly shaped tile cells. However, other features of the xylem indicate a close natural relationship between Chattawaya and the extant paleotropical genus, Pterospermum. It is suggested that the xylem organization of the Eocene fossil represents a more primitive condition than that observed in Pterospermum. Comparative xylotomy indicates three evolutionary trends within the complex to which Chattawaya and Pterospermum belong: development of storied structure, increased uniformity in shape and size of tile cells and loss of multiseriate rays. Chattawaya is part of a growing body of paleobotanical evidence indicating that the Sterculiaceae was well differentiated by the early Tertiary, but that the lineages leading to extant genera have undergone an appreciable amount of evolutionary change since the Eocene.     

3D Morphometric Analysis Reveals Similar Ecomorphs for Early Kangaroos (Macropodidae) and Fanged Kangaroos (Balbaridae) from the Riversleigh World Heritage Area,Australia

Understanding feeding ecology of extinct kangaroos is fundamental to understanding the evolution of kangaroos and the Australia paleoenvironment during the Oligo-Miocene. Comparisons with extant species have suggested that the macropodiforms of the Oligo/Miocene (kangaroos and allies) from the Riversleigh World Heritage Area, northern Australia, were predominantly folivorous browsers or fungivores, unlike the majority of extant species. To further test this hypothesis, we investigate the relationship between variation in cranial and mandibular shape of extant and extinct macropodiforms and ecological factors such as diet, locomotion, and body mass using 3D geometric morphometric analysis of 42 living species and eight extinct species from two radiations (the extinct clade of Balbaridae and some early representatives of the extant Macropodidae. Dietary class (fungivore, browser, grazer, and mixed feeder) correlated strongly with variation in cranial shape (20–25% of variance explained). There was also significant association between cranial shape, and both locomotor mode and body mass. In a principal component analysis of shape variation for crania (including the shape of the molar row), Riversleigh macropodiforms cluster with extant folivorous browsers on principal components (PC) 1 and 3, providing support for previous interpretations of these species as browsing kangaroos. However, as a group and regardless of phylogenetic association, the shape centroid of extinct species differs significantly from that of extant species. Riversleigh macropodiforms cluster with regular hoppers or arboreal tree kangaroos, but this may be a result of the correlation between diet and locomotor mode in kangaroos. Their similarity to extant browsers supports previous interpretations of rainforest and woodland environments at Riversleigh during the early and middle Miocene, respectively. Procrustes ANOVA Analysis of the full shape dataset and diet also shows that diet accounts for a significant portion of variation; however, when phylogeny is taken into account these results become nonsignificant. In analyses of dentary shape, some balbarid species cluster with extant mixed feeders, although this may reflect phylogenetic differences rather than ecological signal.

     

Early evolution and biogeography of lorisiform strepsirrhines

This brief review summarizes new paleontological and molecular data that together support a late middle Eocene Afro-Arabian origin for crown Lorisiformes. Phylogenetic analysis indicates that late Eocene Karanisia is a possible stem lorisiform, late Eocene Saharagalago and Wadilemur and Miocene Komba are stem galagids, and early Miocene Mioeuoticus and Progalago may be crown lorisids. Character evolution along the lorisid and galagid stem lineages is reconstructed as having occurred primarily in postcranial and dental morphology, respectively. These patterns have important implications for interpreting an early lorisiform fossil record that is still composed primarily of jaws and isolated teeth.     

Middle Eocene Pelagornithidae and Gaviiformes (Aves) from the Ukrainian Paratethys

Abstract: We describe avian remains from Novopskov, a new middle Eocene marine locality in Ukraine. The fossils constitute the most substantial collection of Palaeogene bird bones from Eastern Europe and contribute to a better knowledge of the Paratethyan seabird fauna. Most of the specimens belong to Pelagornithidae (bony‐toothed birds), and two species of very different size can be distinguished. The larger of these is tentatively referred to Dasornis sp., the smaller to Odontopteryx toliapica. The specimens include skeletal elements that were not described for Palaeogene bony‐toothed birds and document previously unknown morphological differences between Palaeogene and Neogene Pelagornithidae. It is argued that the purported crane Eobalearica tugarinovi, from the middle Eocene of Kyrgyzstan, is probably also a bony‐toothed bird. A new genus and species of small Gaviiformes, Colymbiculus udovinchenkoi, is described, which is the earliest fossil record of a loon from Europe, preceding the next oldest specimens by more than 10 myr. The Ukrainian fossils document profound differences between middle Eocene and extant marine avifaunas of Europe, and whereas the middle Eocene Paratethyan avifauna appears to have been similar to that of the North Sea with regard to pelagornithid diversity, the absence of prophaethontids and relative abundance of Gaviiformes may indicate faunistic differences concerning the remaining seabirds.