Tertiary Fossil Record Research Articles

A new cracticid (Passeriformes: Cracticidae) from the Early Miocene of Australia

The Cracticidae (Passeriformes) is an endemic Australo-Papuan family that, for the purposes of this paper, comprises the butcherbirds and Australian Magpie (Cracticus), currawongs (Strepera) and peltops (Peltops). Here we describe a new genus and species of cracticid from an Early Miocene deposit in the Riversleigh World Heritage Area, northwestern Queensland, Australia. Kurrartapu johnnguyeni, gen. nov., sp. nov. is described from a proximal tarsometatarsus that is similar in size to that of the extant Black Butcherbird (C. quoyi). This new species shares morphological features with the Strepera—Cracticus clade to the exclusion of Peltops, which suggests that it is a representative of the crown-group Cracticidae. Kurrartapu johnnguyeni represents the first Tertiary record of the Cracticidae in Australia, and is in concordance with molecular estimates for the timing of the cracticid radiation. We also describe morphological differences of the tarsometatarsus between cracticids and woodswallows (Artamus) which have at times been considered confamilial. We add this new cracticid to the expanding Tertiary fossil record of passerines in Australia, which plays a significant role in our understanding of early passerine evolution.

Chronology of the Eocene continental deposits of Africa: Magnetostratigraphy and biostratigraphy of the El Kohol and Glib Zegdou Formations, Algeria

Despite numerous discoveries that have considerably enriched the African-Arabian Tertiary fossil record over the last decades, our knowledge of the evolutionary history of many continental African vertebrate groups during the Paleogene period remains inadequate, particularly when it is compared with the fossil records of Europe or North America. The Eocene Epoch in Africa is especially poorly documented, being restricted to few fossiliferous localities. Our understanding of the early Tertiary emergence, diversification, and paleobiogeographic history of African-Arabian mammals has been further hindered by the lack of a precise temporal framework for these sites. We conducted magnetostratigraphic analyses, associated with biostratigraphic studies, in the fossiliferous sequences exposed in the northwestern Hammadas of the Saharan Platform in the Glib Zegdou area and in the Saharan Atlas at the El Kohol locality (Algeria) to further define the age of these Eocene continental deposits. Based on biostratigraphic constraints, the six polarity zones identified in the El Kohol section can be correlated with chrons C24n to C22r, providing the first direct age estimates for the El Kohol fossiliferous strata between 52 and 51 Ma. Correlation to the geomagnetic polarity time scale, using previously published biostratigraphic data for the Glib Zegdou fauna, suggests an age ranging between 49 and 45 Ma for this section. The high-resolution magnetostratigraphic study of the poorly known continental Eocene Epoch of Algeria provides new insights into the early Tertiary stratigraphy of northwest Africa. The placement of the Algerian localities into a consistent chronological framework constitutes considerable advancement to achieve biostratigraphic correlation of the Paleogene African-Arabian mammal localities.

Generic phylogeny, historical biogeography and character evolution of the cosmopolitan aquatic plant family Hydrocharitaceae

BackgroundHydrocharitaceae is a fully aquatic monocot family, consists of 18 genera with approximately 120 species. The family includes both fresh and marine aquatics and exhibits great diversity in form and habit including annual and perennial life histories; submersed, partially submersed and floating leaf habits and linear to orbicular leaf shapes. The family has a cosmopolitan distribution and is well represented in the Tertiary fossil record in Europe. At present, the historical biogeography of the family is not well understood and the generic relationships remain controversial. In this study we investigated the phylogeny and biogeography of Hydrocharitaceae by integrating fossils and DNA sequences from eight genes. We also conducted ancestral state reconstruction for three morphological characters.ResultsPhylogenetic analyses produced a phylogeny with most branches strongly supported by bootstrap values greater than 95 and Bayesian posterior probability values of 1.0. Stratiotes is the first diverging lineage with the remaining genera in two clades, one clade consists of Lagarosiphon, Ottelia, Blyxa, Apalanthe, Elodea and Egeria; and the other consists of Hydrocharis-Limnobium, Thalassia, Enhalus, Halophila, Najas, Hydrilla, Vallisneria, Nechamandra and Maidenia. Biogeographic analyses (DIVA, Mesquite) and divergence time estimates (BEAST) resolved the most recent common ancestor of Hydrocharitaceae as being in Asia during the Late Cretaceous and Palaeocene (54.7-72.6 Ma). Dispersals (including long-distance dispersal and migrations through Tethys seaway and land bridges) probably played major roles in the intercontinental distribution of this family. Ancestral state reconstruction suggested that in Hydrocharitaceae evolution of dioecy is bidirectional, viz., from dioecy to hermaphroditism, and from hermaphroditism to dioecy, and that the aerial-submerged leaf habit and short-linear leaf shape are the ancestral states.ConclusionsOur study has shed light on the previously controversial generic phylogeny of Hydrocharitaceae. The study has resolved the historical biogeography of this family and supported dispersal as the most likely explanation for the intercontinental distribution. We have also provided valuable information for understanding the evolution of breeding system and leaf phenotype in aquatic monocots.

Phylogeny and biogeography of Alangiaceae (Cornales) inferred from DNA sequences, morphology, and fossils

Alangiaceae, in the basal Asterid clade Cornales, consists of only one genus, Alangium. The genus has approximately 24 species distributed mainly in tropical and subtropical regions of the Old World and is well represented in the Tertiary fossil record of the northern hemisphere. We conducted phylogenetic and biogeographic analyses for Alangium by integrating data from DNA sequences, morphology, and fossils to evaluate systematic and biogeographic hypotheses. The results largely agree with the traditional classification of four sections within the genus, and suggest sects. Conostigma and Rhytidandra are successive sister taxa to a clade containing sects. Marlea and Alangium. Our results also indicate that the widespread species A. chinense consists of at least two lineages meriting recognition as distinct species. Biogeographic analysis using DIVA and divergence time dating with the Bayesian method (MULTIDIVTIME) resolved the ancestor of Alangium as being in S.E. Asia in the Late Cretaceous. Several intercontinental migrations involving the margin of the Tethys seaway (TESW), the North Atlantic land bridge (NALB) or the Bering land bridge (BLB), and long-distance dispersals are suggested. The results support TESW for plant migration of thermophilic (including evergreen) taxa in the early Tertiary.

The geography of diversification in the mormoopids (Chiroptera: Mormoopidae)

The traditional explanation of the distribution of the Mormoopidae is that this family originated in southern Central America or northern South America, later expanding its range north to Mexico and the West Indies, and differentiating into eight species. An alternative fossil-based hypothesis argues that the family originated in the northern Neotropics, reached the Caribbean early in its history, and dispersed to South America after the completion of the Isthmus of Panama. The present study analyses new and previously published sequence data from the mitochondrial 12S, tRNAval, 16S, and cytochrome b, and the nuclear Rag2, to evaluate species boundaries and infer relationships among extant taxa. Fixed differences in cytochrome b often coincide with published morphological characters and show that the family contains at least 13 species. Two additional, morphologically indistinct, lineages are restricted to Suriname and French Guiana. Phylogeny-based inferences of ancestral area are equivocal on the geographical origin of mormoopids, in part because several internal nodes are not resolved with the available data. Divergences between Middle American and Antillean populations are greater than those between Mexico/Central America and South America. This suggests that mormoopids diversified in northern Neotropics before entering South America. A northern neotropical origin for mormoopids is congruent with both the Tertiary fossil record and recent phylogenetic hypotheses for the sister family to the Mormoopidae, the Phyllostomidae.

A PLIOCENE RECORD OF CAPROMERYX (MAMMALIA: ANTILOCAPRIDAE) IN MÉXICO

The Antilocapridae was a diverse artiodactyl family present in some late Tertiary faunas of North America. In Mexico, its Tertiary fossil record is poorly known. The antilocaprid material described in this paper was collected from the early Blancan fluvial deposits of the San Miguel de Allende Area, state of Guanajuato, Mexico. It includes isolated upper and lower premolars and molars, dental series, and some rami fragments. The material is assigned to Capromeryx tauntonensis . The presence of this species in the early Pliocene of central Mexico represents the oldest record in North America and extends its known geographic distribution from the northwestern United States to central Mexico.

A Pliocene record of Capromeryx (Mammalia: Antilocapridae) in México

The Antilocapridae was a diverse artiodactyl family present in some late Tertiary faunas of North America. In México, its Tertiary fossil record is poorly known. The antilocaprid material described in this paper was collected from the early Blancan fluvial deposits of the San Miguel de Allende Area, state of Guanajuato, México. It includes isolated upper and lower premolars and molars, dental series, and some rami fragments. The material is assigned to Capromeryx tauntonensis. The presence of this species in the early Pliocene of central México represents the oldest record in North America and extends its known geographic distribution from the northwestern United States to central México.

Ferns diversified in the shadow of angiosperms.

The rise of angiosperms during the Cretaceous period is often portrayed as coincident with a dramatic drop in the diversity and abundance of many seed-free vascular plant lineages, including ferns. This has led to the widespread belief that ferns, once a principal component of terrestrial ecosystems, succumbed to the ecological predominance of angiosperms and are mostly evolutionary holdovers from the late Palaeozoic/early Mesozoic era. The first appearance of many modern fern genera in the early Tertiary fossil record implies another evolutionary scenario; that is, that the majority of living ferns resulted from a more recent diversification. But a full understanding of trends in fern diversification and evolution using only palaeobotanical evidence is hindered by the poor taxonomic resolution of the fern fossil record in the Cretaceous. Here we report divergence time estimates for ferns and angiosperms based on molecular data, with constraints from a reassessment of the fossil record. We show that polypod ferns (> 80% of living fern species) diversified in the Cretaceous, after angiosperms, suggesting perhaps an ecological opportunistic response to the diversification of angiosperms, as angiosperms came to dominate terrestrial ecosystems.

A NEW BAT (CHIROPTERA: NATALIDAE) FROM THE EARLY MIOCENE OF FLORIDA, WITH COMMENTS ON NATALID PHYLOGENY

We describe a new extinct genus and species of bat belonging to the endemic Neotropical family Natalidae (Chiroptera) from the Thomas Farm Local Fauna in northern peninsular Florida of early Miocene age (18‐19 million years old). The natalid sample from Thomas Farm consists of 32 fossils, including a maxillary fragment, periotics, partial dentaries, isolated teeth, humeri, and radii. A proximal radius of an indeterminate natalid is reported from the I-75 Local Fauna of early Oligocene age (about 30 million years old), also from northern Florida. These fossils from paleokarst deposits in Florida represent the 1st Tertiary records of the Natalidae. Other extinct Tertiary genera previously referred to the Natalidae, including Ageina, Chadronycteris, Chamtwaria, Honrovits, and Stehlinia, may belong to the superfamily Nataloidea but do not fit within our restricted definition of this family. Eight derived characters of the Natalidae sensu stricto are discussed, 5 of which are present in the new Miocene genus. Intrafamilial phylogenetic analysis by parsimony of the Natalidae suggests that the 3 living subgenera, Natalus (including N. major, N. stramineus, and N. tumidirostris), Chilonatalus (including C. micropus and C. tumidifrons), and Nyctiellus (including N. lepidus), deserve full generic rank. The Natalidae apparently evolved in North America before the late Oligocene, went extinct in what is now the Nearctic region (i.e., Florida) after the early Miocene, and survived in tropical Middle America during the remainder of the Tertiary. The presence of 2 endemic genera and 4 endemic species suggests that natalids reached the West Indies by overwater dispersal early in their history (Oligocene or Miocene). The lack of a Tertiary fossil record, marginal distribution, and limited species richness and endemism of natalids in South America are suggestive of a comparatively late arrival on that continent, possibly in the late Pliocene after the beginning of the Great American Faunal Interchange.

Single origin of Malagasy Carnivora from an African ancestor.

The Carnivora are one of only four orders of terrestrial mammals living in Madagascar today. All four (carnivorans, primates, rodents and lipotyphlan insectivores) are placental mammals with limited means for dispersal, yet they occur on a large island that has been surrounded by a formidable oceanic barrier for at least 88 million years, predating the age of origin for any of these groups. Even so, as many as four colonizations of Madagascar have been proposed for the Carnivora alone. The mystery of the island's mammalian origins is confounded by its poor Tertiary fossil record, which leaves us with no direct means for estimating dates of initial diversification. Here we use a multi-gene phylogenetic analysis to show that Malagasy carnivorans are monophyletic and thus the product of a single colonization of Madagascar by an African ancestor. Furthermore, a bayesian analysis of divergence ages for Malagasy carnivorans and lemuriforms indicates that their respective colonizations were temporally separated by tens of millions of years. We therefore conclude that a single event, such as vicariance or common dispersal, cannot explain the presence of both groups in Madagascar.

Identifying Tertiary Radiations of Fabaceae in the Greater Antilles: Alternatives to Cladistic Vicariance Analysis

The fossil record shows that the legume family was abundant and taxonomically diverse in Early Tertiary tropical deciduous forests of North America. Today, woody members of this family are almost nonexistent in temperate deciduous forests. This former North American legume diversity now lies in the Tropics, including the Greater Antilles. To show the Antillean refugia, we detail a phylogenetic and biogeographic analysis of two legume groups, the Ormocarpum and Robinia clades, which have either a Tertiary fossil record in North America or a sister clade with such a fossil record. A combined analysis of molecular and nonmolecular data is used for the cladistic vicariance approaches, while an exhaustively sampled data set of nrDNA ITS/5.8S sequences is used for the molecular biogeographic analysis. Results from component, three‐area‐statements, and Brooks parsimony analysis are equivocal in suggesting an influence of Tertiary history on the distribution of the woody genera Pictetia (Ormocarpum clade) and Poitea (Robinia clade), two of the most speciose endemic legume radiations in the Greater Antilles. Alternatively, nucleotide diversity, evolutionary rates, and coalescent analyses of molecular phylogenies all suggest a Tertiary diversification of Pictetia and Poitea. The results are corroborated by a regression analysis that implicates both age of island biota and island area in accurately predicting numbers of endemic legume taxa. These findings, combined with the legume fossil record, suggest that both Pictetia and Poitea stem from Tertiary North American boreotropical groups. J. A. Wolfe’s hypothesis that the Greater Antilles harbor boreotropical relicts is supported.

A fossil fern indicator of epiphytism in a Tertiary flora.

The first known indicator of probable fern epiphytism in the Tertiary fossil record is documented from the Eocene London Clay of southeast England. This pyritised fern rachis exhibits major deviation from the basic form of petiolar vascular trace morphology shown by the other London Clay fossil ferns and is here attributed to the Polypodiaceae. This represents the first known occurrence of this family in the London Clay macroflora, and brings the total of distinct fern rachis types from the Lower Tertiary of southeast England to six. The significance of this find is interpreted in relation to its probable origins from a tropical rainforest palaeoflora in which it is proposed that this specimen represents the first occurrence of an epiphytic component.

Inflorescence Bracts of Fossil and Extant Tilia in North America, Europe, and Asia: Patterns of Morphologic Divergence and Biogeographic History

The enlarged inflorescence bract diagnostic of extant Tilia has an extensive Tertiary fossil record in the Northern Hemisphere. Diversity of bract morphology, and the extent of adnation between peduncle and bract, is reviewed for fossil and extant species of Tilia. An extinct type of bract with an orbicular outline and palmate venation is documented by the fossil species Tilia circularis (Chaney) comb. nov. from the early Oligocene of Oregon and is designated Type A. Living species of the genus have elongate bracts with predominately pinnate venation that are borne in two basic configurations: Type B, with the peduncle fused only to the extreme base of the bract lamina, as in extant Tilia endochrysea Hand.-Mzt. of southern China; and Type C with the peduncle fused medially along the basal one-third of the bract lamina, as in most extant species. Bracts of Type B were widely distributed in the Tertiary of western North America (late Eocene to Miocene) and Europe (early Miocene to Pliocene), while those of Type C are known in the fossil condition only from the middle and late Tertiary of Asia and Pliocene of Europe. The bracts of T. circularis, like those of type B, are borne on relatively long stalks and have the peduncle fused only at the extreme base. The fossil record supports recognition of the following characters as apomorphic in Tilia bract evolution: bracts sessile, peduncle adnate to the upper surface of the bract, and pinnate bract venation.

Inflorescence bracts of fossil and extant Tilia in North America, Europe, and Asia: patterns of morphologic divergence and biogeographic history

The enlarged inflorescence bract diagnostic of extant Tilia has an extensive Tertiary fossil record in the Northern Hemisphere. Diversity of bract morphology, and the extent of adnation between peduncle and bract, is reviewed for fossil and extant species of Tilia. An extinct type of bract with an orbicular outline and palmate venation is documented by the fossil species Tilia circularis (Chaney) comb. nov. from the early Oligocene of Oregon and is designated Type A. Living species of the genus have elongate bracts with predominately pinnate venation that are borne in two basic configurations: Type B, with the peduncle fused only to the extreme base of the bract lamina, as in extant Tilia endochrysea Hand.‐Mzt. of southern China; and Type C with the peduncle fused medially along the basal one‐third of the bract lamina, as in most extant species. Bracts of Type B were widely distributed in the Tertiary of western North America (late Eocene to Miocene) and Europe (early Miocene to Pliocene), while those of Type C are known in the fossil condition only from the middle and late Tertiary of Asia and Pliocene of Europe. The bracts of T. circularis, like those of type B, are borne on relatively long stalks and have the peduncle fused only at the extreme base. The fossil record supports recognition of the following characters as apomorphic in Tilia bract evolution: bracts sessile, peduncle adnate to the upper surface of the bract, and pinnate bract venation.

ORIGINS AND RELATIONSHIPS OF TROPICAL NORTH AMERICA IN THE CONTEXT OF THE BOREOTROPICS HYPOTHESIS

The boreotropics hypothesis postulates a preferential tropical biotic interchange between North America and Eurasia during the early Tertiary that was directed by Eocene thermal maxima and the close proximity of these two continental plates. This preferential interchange occurred at a time when South America was geologically and biotically isolated. A prediction of this hypothesis posits that a taxon with a present‐day center of diversity in tropical North America, and with an early Tertiary fossil record from any region there, has a high probability of having sister‐group relatives in the Paleotropics and derived relatives in South America. We propose a test of this prediction with phylogenetic studies of two pantropical taxa of Leguminosae that have early Tertiary North American fossil records. Our findings are consistent with the boreotropics hypothesis, and additional evidence suggests that many tropical elements in North America could be descendants of northern tropical progenitors. Ramifications of this hypothesis include the importance of integrating the fossil record with cladistic biogeographic studies, theoretical bases for recognizing tropical taxa with such disjunct distributions as Mexico and Madagascar, identification of taxa that may be most useful for testing vicariance models of Caribbean biogeography, and integrating the study of disjunct distributions in temperate regions of the northern hemisphere with those in the neo‐ and paleotropics.

Insect leaf mines from the Eocene Anglesea locality, Victoria, Australia

The first Tertiary leaf mines described from Australia are six mines from the Anglesea locality in Victoria. They are referable to five leaf mining taxa. Two of the mines are associated with a Lauraceae leaf. A third leaf mine is preserved in a ‘mummified’ leaf with affinities to Elaeocarpaceae. The remaining two mines are on leaves that are too poorly preserved to be identified. Four of these fossil leaf mines are thought to belong to Lepidoptera and two are probably referable to the Nepticulidae. The remaining mine could be either dipteran or lepidopteran. These mines are the only evidence of the Lepidoptera in the Tertiary fossil record in Australia.

Piptochaetium (Gramineae) and Associated Taxa: Evidence for the Tertiary Migration of Plants Between North and South America

Disjunct distributions are frequent among higher plant taxa and the paucity of detailed fossil records for such plants, especially herbs, has rendered explanation of dispersal difficult. The late Tertiary fossil record of central North America provides data on the history of a number of herbaceous taxa which are now disjunctly distributed in amphitropical America and between North America and Eurasia. The North American Tertiary data provide evidence supporting the concurrence of evolution of herbaceous taxa and grazing mammals. Extensive migrations of grazing mammals occurred after the Central American land bridge emerged in middle Pliocene time. It is concluded, on the basis of available modern and fossil data, that these plants may reasonably have crossed the land bridge with animals with which they had evolved a degree of interdependence. The applicability of the hypothesis of long distance dispersal to the case of amphitropical American disjunctions is reviewed and certain deficiencies of the hypothesis are noted. In view of the data presented in this paper, it is concluded that the observed pattern of amphitropical American plant taxa disjunctions is the result of the combined processes of migration and long distance dispersal.

GENETIC VARIATION IN THE HORSESHOE CRAB (LIMULUS POLYPHEMUS), A PHYLOGENETIC "RELIC".

To many early evolutionists, particularly those of mutationist school, existence of evolutionarily stable forms (living fossils or phylogenetic relics) posed difficult problem, and, even among contemporary biologists, feeling that a long-standing stability of organization seems antithetical to concept of may persist (Volpe, 1967:140). In early part of this century, it was popularly believed that stable or slowly evolving (bradytelic) lines lacked genetic variation necessary for more rapid evolution as result of having abnormally low mutation rates; as Mayr (1963) puts it, lack of variation in time and space was interpreted as reflection of genotypic stability. Largely because of influence of Simpson (1944), Stebbins (1944), Schmalhausen (1949), and Dobzhansky (1951), mutationists' interpretation of has now been all but abandoned by evolutionists in favor of view that principal factors controlling rates of evolution are to be found in organism-environment relationship. Additionally, Mayr (1963 :304) has suggested that phenotypic uniformity in space and time is due to highly perfected 'buffering system,' in other words, to genetic homeostasis. The ecological hypothesis is well expressed in Simpson's (1944:141) conclusions that the final and probably most fundamental factor in relationship is that bradytelic groups are so well adapted to particular, continuously available environment that almost any mutation occurring in them must be disadvantageous and that bradytely results from equilibrium of large breeding populations of animals specifically adapted to continuously available environment that is relatively invariable . Yet, as Mayr (1963) notes, there is no evidence to refute (or to support) hypothesis that results from loss of mutability. The recent development of electrophoretic techniques for demonstrating allelic variation at loci controlling enzymes and other proteins in natural populations (Hubby and Lewontin, 1966; Lewontin and Hubby, 1966) permits test of mutationists' thesis. The purpose of this study is to compare degrees of protein polymorphism and underlying genic heterozygosity in classic phylogenetic relic, horseshoe or king crab (Limulus polyphemus), and in several representatives of horotelic lines (those evolving at standard rates) for which data are already available. Evidence of level of genetic variation in Limulus similar to that in horotelic forms will support modern ecological and homeostatic interpretations of bradytely. But if mutationists' thesis is valid, Limulus should show an unusually low degree of polymorphism at its genetic loci. Limulus polyphemus is one of five living species of Subclass Xiphosura, group of marine arthropods usually placed with Subclass Eurypterida (extinct giant water scorpions) in Class Merostomata of Subphylum Chelicerata. Following period of adaptive radiation in early and middle Paleozoic, Merostomata became much less prominent after Permian. Several Mesozoic forms are known in Family Mesolimulidae, but by Tertiary fossil record is all but absent. There are presently three living genera, all belonging to Family Limulidae, only one of which, Tachypleus, is known from fossil record (Stormer,

A Contribution to the Early Tertiary Fossil Record of the Salviniaceae

A Contribution to the Early Tertiary Fossil Record of the Salviniaceae