Notharctine primates (Adapiformes) from the early to middle Eocene (Wasatchian-Bridgerian) of Wyoming: transitional species and the origins of Notharctus and Smilodectes

Notharctine adapiform primates are an abundant element of early (Wasatchian) and middle (Bridgerian) Eocene faunal assemblages from the western interior of North America. Early Eocene notharctine samples are dominated by Cantius with Pelycodus and Copelemur being much rarer and more restricted in their geographic distribution. Cantius is replaced in the middle Eocene by Notharctus and Smilodectes, both of which are common but less widespread, being best known from southwestern Wyoming. The origin of these two middle Eocene taxa has not been well understood, due to a lack of transitional Wasatchian-Bridgerian notharctine faunal samples or because known samples had not been adequately studied. Field work at South Pass in the Greater Green River Basin has produced a relatively large sample of earliest Bridgerian notharctines. Combining this sample with a large, but previously under-studied, sample of notharctines from the latest Wasatchian and earliest Bridgerian in the Wind River Basin has clarified the relationships among Notharctus,Smilodectes, and earlier occurring notharctines. Notharctus first appears in the latest Wasatchian (Wa7), represented by N. venticolus. Phylogenetic analysis supports a Notharctus clade that shares sister taxon status with Cantius nunienus and indicates that Notharctus arose through bifurcation of the lineage containing the last common ancestor of C. nunienus and Notharctus. The origins of Smilodectes are less clear. Phylogenetic analysis supports a clade consisting of Smilodectes and Copelemur, but the origins of both taxa are not established as yet. North American notharctines are typified by relatively low taxonomic diversity, but relatively high abundance and high dental morphological variation (disparity). These attributes are opposite to those of North American omomyids, reflecting differences in ecomorphospace between these two primate radiations.     

Jemezius,a new omomyid primate from the early Eocene of northwestern New Mexico

Recently collected omomyid primate fossils from the early Eocene Regina Member, San Jose Formation, San Juan Basin, New Mexico, add significant new information to our knowledge of the family in the southern part of the Rocky Mountain region during Wasatchian time. A total of seven specimens represent at least two omomyid species on the basis of size alone, but only the larger of these species, here described as Jemezius szalayi, gen. et sp. nov., is currently known from sufficient material to permit an adequate taxonomic assignment. Jemezius possesses several traits in common with Uintanius that clearly reflect a close phylogenetic relationship between these genera, but lacks the specialized premolar hypertrophy characteristic of that genus. The presence of uintaniinin omomyids in New Mexico during the middle Wasatchian, well before their first appearance in Wyoming during Bridgerian time, supports the hypothesis that several of the exotic mammals that first appear in Wyoming near the Wasatchian-Bridgerian boundary may be immigrant taxa from the south.     

Phylogenetic relationships among the Notharctinae of North America

Study of over 1,000 specimens representing all notharctine genera and species leads to the conclusion that current concepts about the relationships of genera within the Notharctinae are incorrect. The following describes the more probable relationships among these genera. 1) Smilodectes and Notharctus are more closely related to each other than either is to any known early Eocene notharctine. Synapomorphies linking these genera include relatively narrow upper and lower molars, a relatively low-crowned P4, and paraconid size reduction on M1-3. 2) Among known Wasatchian notharctines, a clade consisting of Copelemur tutus and Cop. praetutus shares several lower molar synapomorphies with the Notharctus-Smilodectes clade, and therefore appears to form the Wasatchian sister group of Bridgerian notharctines. Synapomorphies documenting this relationship include well-developed entoconid notches on P4-M2, an anteriorly placed paraconid on M2, and a long premetacristid on M2. 3) Copelemur and Pelycodus are independently derived from early North American Cantius. Recent suggestions that the European adapine taxa Leptadapis priscus and Microadapis sciureus share special phylogenetic relationships with Smilodectes are rejected. The reduced (or lack of a) paraconid and morphology of the paracristid and other features identified as synapomorphies linking these adapines with Smilodectes are also characteristic of most other adapines as well (e.g., other species of Leptadapis, Adapis, Europolemur, and Anchomomys). Such traits developed independently in Smilodectes, which is clearly a notharctine on the basis of many synapomorphies and thus are not evidence of a close phylogenetic relationship between Smilodectes and L. priscus or M. sciureus.     

New notharctine (primates,adapiformes) skull from the Uintan (middle Eocene) of San Diego County,California

A new genus and species of notharctine primate, Hesperolemur actius, is described from Uintan (middle Eocene) aged rocks of San Diego County, California. Hesperolemur differs from all previously described adapiforms in having the anterior third of the ectotympanic anulus fused to the internal lateral wall of the auditory bulla. In this feature Hesperolemur superficially resembles extant cheirogaleids. Hesperolemur also differs from previously known adapiforms in lacking bony canals that transmit the internal carotid artery through the tympanic cavity. Hesperolemur, like the later occurring North American cercamoniine Mahgarita stevensi, appears to have lacked a stapedial artery. Evidence from newly discovered skulls of Notharctus and Smilodectes, along with Hesperolemur, Mahgarita, and Adapis, indicates that the tympanic arterial circulatory pattern of these adapiforms is characterized by stapedial arteries that are smaller than promontory arteries, a feature shared with extant tarsiers and anthropoids and one of the characteristics often used to support the existence of a haplorhine-strepsirhine dichotomy among extant primates. The existence of such a dichotomy among Eocene primates is not supported by any compelling evidence. Hesperolemur is the latest occurring notharctine primate known from North America and is the only notharctine represented among a relatively diverse primate fauna from southern California. The coastal lowlands of southern California presumably served as a refuge area for primates during the middle and later Eocene as climates deteriorated in the continental interior. Hesperolemur probably was an immigrant taxon that entered California from either the northern (Wyoming/Utah) or southern (New Mexico) western interior during the middle Eocene © 1995 Wiley-Liss, Inc.     

New early Eocene anaptomorphine primate (Omomyidae) from the Washakie Basin,Wyoming, with comments on the phylogeny and paleobiology of anaptomorphines

Recent paleontological collecting in the Washakie Basin, southcentral Wyoming, has resulted in the recovery of over 100 specimens of omomyid primates from the lower Eocene Wasatch Formation. Much of what is known about anaptomorphine omomyids is based upon work in the Bighorn and Wind River Basins of Wyoming. This new sample documents greater taxonomic diversity of omomyids during the early Eocene and contributes to our understanding of the phylogeny and adaptations of some of these earliest North American primates. A new middle Wasatchian (Lysitean) anaptomorphine, Anemorhysis savagei, n. sp., is structurally intermediate between Teilhardina americana and other species of Anemorhysis and may be a sister group of other Anemorhysis and Trogolemur. Body size estimates for Anemorhysis, Tetonoides, Trogolemur, and Teilhardina americana indicate that these animals were extremely small, probably less than 50 grams. Analysis of relative shearing potential of lower molars of these taxa indicates that some were primarily insectivorous, some primarily frugivorous, and some may have been more mixed feeders. Anaptomorphines did not develop the extremes of molar specialization for frugivory or insectivory seen in extant prosimians. Incisor enlargement does not appear to be associated with specialization in either fruits or insects but may have been an adaptation for specialized grooming or food manipulation. © 1994 Wiley-Liss, Inc.     

Evolution of the mandibular symphysis in Notharctinae (Adapidae,Primates)

The Eocene Notharctinae provide a record of increasing fusion of the mandibular symphysis. The two sympatric genera,Notharctus andSmilodectes, differed through time in two respects.Notharctus increased in body size and evolved a partially fused mandibular symphysis.Smilodectes changed little in body size and retained an unfused symphysis. Similarities in molar morphology between these two genera and extant leaf-eating mammals suggest thatNotharctus andSmilodectes were specialized for folivory, a dietary regime correlated with partial symphyseal fusion in many extant mammals. It is concluded that the presence and the extant of symphyseal fusion is a function of body size, diet, and jaw mechanics, complicated by lineagespecific factors that vary among higher mammalian taxa.     

Wasatchian (Early Eocene) pollen floras from the Red Hot Truck Stop, Mississippi, USA

Sediments at the Red Hot Truck Stop (RHTS), Mississippi, USA are important because they contain the lowest latitude record of both the earliest known Eocene plant and mammal fossils in North America. The RHTS contains the uppermost Tuscahoma Formation and the lowermost part of the basal Bashi and Hatchetigbee formations. The Tuscahoma Formation is composed of glauconitic sands and silts that represent estuarine to shallow marine sediments. Faunal remains indicate that the RHTS section belongs to the Wasatchian North American land mammal age and specifically to the lower Graybullian subdivision. Pollen and spore floras from the RHTS are moderately diverse (113 taxa) and contain families that today are associated with warm‐adapted vegetation types such as Annonaceae, Bombacaceae, Burseraceae and palms. Eocene first occurrences are represented by Brosipollis sp., Celtispollenites sp., Interpollis microsupplingensis, cf. Nuxpollenites psilatus, Platycarya spp., Retistephanocolporites sp. and Symplocos? contracta and by one genus of pteridophyte spore (Granulatisporites sp.). The overall composition and within‐sample diversity of the sporomorph flora is more similar to the Hatchetigbee Formation (early Eocene) than to the middle Tuscahoma Formation (late Palaeocene) but among‐sample diversity remains unchanged across the Palaeocene/Eocene boundary. The distinct composition of the RHTS demonstrates that floral change across the Palaeocene/Eocene boundary is complex and composed of several phases of floral change.     

Deciduous premolars of Eocene Equidae and their phylogenetic significance

Abstract

The deciduous premolars of early Eocene Equidae from North America, conventionally attributed to ‘Hyracotherium’, are described and compared, based primarily on a sample of >60 specimens from the early Eocene Willwood Formation of the Bighorn Basin, Wyoming. The sample represents six to nine species assigned to multiple genera by some other authors, but in the absence of diagnostic characters of the deciduous dentition, species assignments remain ambiguous for most specimens. Consequently it is not clear which generic names should be applied, and we employ the widespread name ‘Hyracotherium’ (acknowledging that the type species may not be an equid). We observed considerable variation in our sample, but most differences are minor and are largely inconsistent with respect to time or taxa, hindering attempts to characterise deciduous premolar anatomy of particular species. Comparisons were also made to Bridgerian Orohippus and Uintan Epihippus, to other early perissodactyls, and to non-perissodactyls that have been considered close to the origin of Perissodactyla (phenacodontid condylarths and Cambaytherium). Based on these comparisons, we confirm Butler’s observation that the deciduous premolars of equids show increasing molarization and lophodonty through the Eocene. However, our evidence suggests that there was little directed change through most of the Wasatchian until Wa-7.     

Diversity starts early: notharctid primates from the Sandcouleean (Early Eocene) of the Powder River Basin,Wyoming, USA

Abstract

Abundant specimens, mostly isolated teeth, of the Primate family Notharctidae occur in the Early Eocene rocks of the Powder River Basin of northeastern Wyoming, USA. Very early in the North American history of the family, the notharctid species diversified and this diversity may have been widespread, and not restricted to more southerly areas in the Rocky Mountains. The diversity is shown by detailed analysis of the molar dentition. Two new genera are established: Megaceralemur with Megaceralemur trigonodus as its type and Megaceralemur matthewi sp. nov. as a Sandcouleean species and Pinolophus, with Pinolophus meikei sp. nov. as its type, for a form with an entoconid notch on lower molar 1. Megaceralemur has a prominent nannopithex-fold which dominates the posterior cingulum of upper molars 1–2 and a cristid obliqua on lower molar 1 which attaches to the metaconid, not the metalophid as it does in Cantius and other genera. A small species, Cantius lohseorum sp. nov., is named for a derived lineage the size of Cantius torresi.

urn:lsid:zoobank.org:pub:066DC515-A2DD-40AF-AD8A-3834E2AFD0FB     

New omomyid primates (Haplorhini, Tarsiiformes) from middle Eocene rocks of west-central Hot Springs County, Wyoming.

Three new genera and four new species of omomyid primates constitute the first record of the Primates from upland middle Eocene rocks of Wyoming. One of these, Strigorhysis, gen. nov., possesses broadly basined molars with highly crenulated enamel which probably indicates a good deal of tough vegetable matter in its diet. Each of the new genera could have descended from known Wasatchian or early middle Eocene anaptomorphines: Aycrossia, gen. nov., is a plausible derivative of Tetonius or Chlororhysis; Strigorhysis, gen. nov., is most similar to Absarokius noctivagus; and Gazinius, gen. nov., most closely resembles Absarokius and Anaptomorphus. The anaptomorphines were probably equally as diverse as the better documented omomyines in the middle Eocene, but may have preferred upland environments at the margins of the Tertiary basins of the Rocky Mountain Interior.     

New adapiform primate of Old World affinities from the Devil's Graveyard Formation of Texas

Most adapiform primates from North America are members of an endemic radiation of notharctines. North American notharctines flourished during the Early and early Middle Eocene, with only two genera persisting into the late Middle Eocene. Here we describe a new genus of adapiform primate from the Devil’s Graveyard Formation of Texas. Mescalerolemur horneri, gen. et sp. nov., is known only from the late Middle Eocene (Uintan) Purple Bench locality. Phylogenetic analyses reveal that Mescalerolemur is more closely related to Eurasian and African adapiforms than to North American notharctines. In this respect, M. horneri is similar to its sister taxon Mahgarita stevensi from the late Duchesnean of the Devil’s Graveyard Formation. The presence of both genera in the Big Bend region of Texas after notharctines had become locally extinct provides further evidence of faunal interchange between North America and East Asia during the middle Eocene. The fact that Mescalerolemur and Mahgarita are both unknown outside of Texas also supports prior hypotheses that low-latitude faunal assemblages in North America demonstrate increased endemism by the late middle Eocene.     

Body size and premolar evolution in the early‐middle eocene euprimates of Wyoming

The earliest euprimates to arrive in North America were larger‐bodied notharctids and smaller‐bodied omomyids. Through the Eocene, notharctids generally continued to increase in body size, whereas omomyids generally radiated within small‐ and increasingly mid‐sized niches in the middle Eocene. This study examines the influence of changing body size and diet on the evolution of the lower fourth premolar in Eocene euprimates. The P₄ displays considerable morphological variability in these taxa. Despite the fact that most studies of primate dental morphology have focused on the molars, P₄ can also provide important paleoecological insights. We analyzed the P₄ from 177 euprimate specimens, representing 35 species (11 notharctids and 24 omomyids), in three time bins of approximately equal duration: early Wasatchian, late Wasatchian, and Bridgerian. Two‐dimensional surface landmarks were collected from lingual photographs, capturing important variation in cusp position and tooth shape. Disparity metrics were calculated and compared for the three time bins. In the early Eocene, notharctids have a more molarized P₄ than omomyids. During the Bridgerian, expanding body size range of omomyids was accompanied by a significant increase in P₄ disparity and convergent evolution of the semimolariform condition in the largest omomyines. P₄ morphology relates to diet in early euprimates, although patterns vary between families. Am J Phys Anthropol 153:15–28, 2014. © 2013 Wiley Periodicals, Inc.     

Lunulichnus Tuberosus Ichnogen. and Ichnosp. Nov. from the Early Eocene Wasatch Formation,Fossil Butte National Monument,Wyoming: An Arthropod-Constructed Trace Fossil Associated with Alluvial Firmgrounds

A new trace fossil, Lunulichnus tuberosus, is described from fluvial deposits of the Wasatch Formation (early Eocene) at Fossil Butte National Monument, southwestern Wyoming, USA. L. tuberosus are straight, vertical to obliquely oriented, unlined cylindrical burrows with pronounced crescent-shaped wall sculptings. In situ examples of these trace fossils are most commonly preserved as sand-filled casts emanating from the erosional bases of fluvial channel sandstone bodies into underlying floodplain mudstone/siltstone beds. L. tuberosus is interpreted as the dwelling trace of a stream-dwelling decapod crustacean. Excellent preservation of fine detail, particularly their diagnostic crescent-shaped wall sculptings, support the hypothesis that L. tuberosus were excavated in firm substrata subjacent to fluvial erosional surfaces. As such, they are interpreted as constituents of alluvial Glossifungites trace fossil assemblages.     

Myrtaceae fossil leaves from the Río Turbio Formation (Middle Eocene), Santa Cruz Province,Argentina

Myrtaceae, the gum tree family, is a large angiosperm clade of 5671 species mostly distributed in tropical and subtropical regions of the world. In the southernmost tip of South America (Santa Cruz province) where the fossils analysed in this study come from (Río Turbio Formation), this family is virtually absent and the extant vegetation is largely dominated by deciduous Nothofagus pumilio and Nothofagus antarctica. During the early Paleogene, however, the Myrtaceae were an important element in southern Patagonian floras. Here, we report and describe ten taxa related to the extant genera Eugenia, Myrcia, Psidium, Myrcianthes and possible Eucalyptus and Campomanesia. The presence of a high diversity of Myrtaceae during the Eocene in one of the southernmost regions of the world could be thought as unusual. However, during this period of time (45 Ma), a number of other tropical lineages also reached these high latitudes probably as a consequence a warming climatic trend. In fact, through the Paleocene–Early Eocene interval, climatic conditions were the warmest of the Cenozoic. After this period of time, a progressive decline in temperature forced the migration of megathermal elements towards lower latitudes and, at the same time, led to the expansion of forest dominated by Nothofagus which predominate the region today.     

The first species of Sinopa (Hyaenodontida,Mammalia) from outside of North America: implications for the history of the genus in the Eocene of Asia and North America

The first Sinopa species, S. jilinia sp. nov., from outside of North America is described. It comes from the Huadian Formation, locality Gonglangtou, Jilin Province, north‐east China. The new species represents the northernmost and one of the latest and most complete Asian Prototomus‐like hyaenodontidans known. It also represents one of the youngest specimens of Sinopa, because the age of the Huadian Formation is correlated to the later Uintan and only one doubtful citation of North American Sinopa younger than the early Uintan exists. S. jilinia sp. nov. is characterized by having m3 clearly smaller than m1, very strong and extended labial molar cingulids, backward leaning protoconids in all molars and its m3 cristid obliquum joining the postvallid very labially. With S. jilina, Sinopa is the first hyaenodontidan genus known to be present on two continents during the time interval between the earliest Eocene (c. 55.0 Ma) and latest middle Eocene (40 Ma). Its occurrence in the Huadian Formation supports the idea of a faunal exchange between North America and Asia in the early middle Eocene, a hypothesis formerly based mainly on the presence of the omomyid primate Asiomomys in the Huadian Formation, on a small radiation of East Asian trogosine tillodonts and on a couple of perissodactyl genera shared between the middle Eocene of North America and the Irdinmanhan of East Asia. As with the new Sinopa species, these Asian taxa had their closest relatives in North America.     

Phylogeny and biogeography of tetralophodont rodents of the tribe Oryzomyini (Cricetidae: Sigmodontinae)

Oryzomyini is the richest tribe among the Sigmodontine rodents, encompassing 32 living and extinct genera and including an increasing number of recently described species and genera. Some Oryzomyini are tetralophodont showing a reduction in the number of molar folds to four, while most taxa in this tribe retain the plesiomorphic pentalophodont state. We applied phylogenetic methods, molecular dating techniques and ancestral area analyses to members of an oryzomyini clade informally named ‘D’ in former studies and included related fossil tetralophodont forms. Based on 98 morphological characters and sequences of five gene fragments, we found that the tetralophodont condition is paraphyletic. Among living taxa, Pseudoryzomys is sister to Holochilus, and Lundomys is derived from a basal divergence. A clade formed by living Holochilus and the fossils Noronhomys and Carletonomys is sister to Holochilus primigenus, making Holochilus paraphyletic. Therefore, we describe a new genus that accommodates the fossil H. primigenus. Because trans‐Andean taxa currently share a common ancestor with taxa of cis‐Adean distribution, the northern Andes uplift may have worked as a postdispersal barrier. The tetralophodont lineages diverged during the Pliocene from a cis‐Andean ancestor, and the Great Plains in South America may have favoured the diversification of tetralophodont forms adapted to open habitats during the Pliocene.     

FRUITS AND SEEDS OF TRIBE GORDONIEAE (THEACEAE) FROM THE EOCENE OF NORTH AMERICA

A new genus and species Gordoniopsis polysperma and two new species of Gordonia (Gordonieae, Camellioideae, Theaceae) are described based on fossil fruit and seed remains. These specimens are part of a large flora consisting of various plant organs from the middle Eocene Claiborne Formation in western Kentucky and Tennessee. Gordoniopsis is a five-valved loculicidally dehiscent capsule similar to capsules of Gordonia but differing in having unwinged seeds and a greater number of seeds per locule. The two Gordonia species are among the earliest unequivocal records of the genus and two of only four fossil Gordonia species known with in situ seeds. Two extinct genera, Gordoniopsis and Andrewsiocarpon, and the extant genus Gordonia in the tribe Gordonieae are known from the middle Eocene Claiborne flora, suggesting an early radiation within the tribe. Based on a survey of Recent fruits and seeds we concur with Keng's proposal to merge Laplacea with Gordonia.     

The Fossil Record of the Epacridaceae

Fossil pollen and macrofossils of Epacridaceae are uncommonand are mainly known from Tasmania and other parts of south-easternAustralia. Most epacrids have generalized ericalean pollen althoughthe pollen of some genera is distinctive. Ericalean pollen isknown from the late Cretaceous. The first occurrence ofParipollisorchesis pollen, which is consistent with some extantEpacrisspecies,probably means that Epacridaceae, and possibly the tribe Epacrideae,had differentiated by the Middle Eocene. The fossil record at present provides minimum ages of the firstoccurrences of major subfamilial taxa. Macrofossils of subfamilyRicheoideae and of several morphotypes of the tribe Epacrideaeare known from the Early Oligocene. Tribe Cosmelieae pollenand macrofossils are known from the Early Pleistocene, and areprobablySprengelia. The oldest Australasian fossils of tribeStyphelieae are leaves in latest Oligocene–Early Mioceneparts of the Latrobe Valley coal. Endocarps identified as Epacridaceaefrom the Eocene of England need further investigation. PollenofMonotoca, or a close relative, is known from the mid-Miocene.PossibleTrochocarpaleaves occur in Late Oligocene/Early Miocenesediments, and fossil leaves indistinguishable from the extantTasmanian rainforest species,T. gunniiandT. cunninghamii, areknown from the Early Pleistocene in Tasmania. Epacridaceae; macrofossils; microfossils; Cretaceous; Cainozoic     

Paleobotanical remains from the Paleocene–lower Eocene Vagadkhol Formation, western India and their paleoclimatic and phytogeographic implications

A small assemblage of macro- and micro floral remains comprising fossil leaf impressions, silicified wood, spores, and pollen grains is reported from the Paleocene–lower Eocene Vagadkhol Formation (=Olpad Formation) exposed around Vagadkhol village in the Bharuch District of Gujarat, western India. The fossil leaves are represented by five genera and six species, namely, Polyalthia palaeosimiarum (Annonaceae), Acronychia siwalica (Rutaceae), Terminalia palaeocatapa and T. panandhroensis (Combretaceae), Lagerstroemia patelii (Lythraceae), and a new species, Gardenia vagadkholia (Rubiaceae). The lone fossil wood has been attributed to a new species, Schleicheroxylon bharuchense (Sapindaceae). The palynological assemblage, consisting of pollen grains and spores, comprises eleven taxa with more or less equal representation of pteridophytes, gymnosperms, and angiosperms. Angiospermous pollen grains include a new species Palmidites magnus. Spores are mostly pteridophytic but some fungal spores were also recovered. All the fossil species have been identified in the extant genera. The present day distribution of modern taxa comparable to the fossil assemblage recorded from the Vagadkhol area mostly indicate terrestrial lowland environment. Low frequency of pollen of two highland temperate taxa (Pinaceae) in the assemblage suggests that they may have been transported from a distant source. The wood and leaf taxa in the fossil assemblage are suggestive of tropical moist or wet forest with some deciduousness during the Paleocene–early Eocene. The presence of many fungal taxa further suggests the prevalence of enough humidity at the time of sedimentation.     

New fossils of ascomycetous anamorphic fungi from Baltic amber

Three new fossils of saprotrophic fungi are presented and described from Baltic amber, dated to Eocene epoch (Paleogene, upper to mid-Eocene). All belong to Ascomycota and are represented by hyphae as well as asexual reproduction structures allowing to assign them to present genera, respectively Periconia, Penicillium and Scopulariopsis. These material provide both the first and the oldest known fossil record of the mentioned taxa, making these data valuable for the knowledge about the evolutionary history of the Ascomycota.