Enamel microstructure evolution in anthracotheres (Mammalia,Cetartiodactyla) and new insights on hippopotamoid phylogeny

Investigations on enamel microstructure provided new data for the debate on hippopotamid origin. Observations indicated a diversity of patterns relevant to phylogenetic inferences. Within Hippopotamoidea, the distribution of these patterns seems to be in favour of a hippopotamid origin within the Palaeogene African anthracotheres. Enamel microcharacters therefore prove to be particularly relevant for future phylogenetic analysis of the superfamily, and have implications for our understanding of ecological transitions within hippopotamoids at the end of the Miocene. Indeed, unlike equids or bovids, which developed grass feeding thanks to their hypsodont molars, hippopotamoids may have had another way to exploit this resource. The combination of inter‐row sheets, which appeared early in the evolutionary history of the group, and the increased thickness of radial enamel could have eased the consumption of highly abrasive graminoids. © 2014 The Linnean Society of London     

Origins of Hippopotamidae (Mammalia, Cetartiodactyla): towards resolution

The old debate on hippopotamid origins is still unresolved, balancing between two main phylogenetic hypotheses: origins within the Anthracotheriidae vs. origins within the Tayassuidae. The characters used in the literature to support one, the other, or both hypotheses were re-examined in light of a better known primitive hippopotamid morphology. A cladistic analysis was performed on the basis of these characters. On the one hand, although many features similar in hippopotamuses and anthracotheres appear to have evolved in parallel, the family Anthracotheriidae remains the best putative hippopotamus stem group on the basis of the reviewed characters. However, the precise identification of a stem group within this family is still uncertain. On the other hand, the lineage proposed in the tayassuid hypothesis should not be retained, being mostly based on some incorrect observations and without taking into account the derived or primitive nature of the features. The anatomic similarities seen between modern peccaries and Hippopotamus amphibius are the results of convergences between advanced species of both families.     

A new species of Kolpochoerus (Mammalia: Suidae) from the Pliocene of Central Afar, Ethiopia: Its Taxonomy and Phylogenetic Relationships

Kolpochoerus (Mammalia: Suidae) is a suine genus represented by a number of species from Plio-Pleistocene sites in Africa. While the general trends in Kolpochoerus evolution are broadly known, gaps in the fossil record preclude an understanding of the details of its evolutionary tempo and mode. Here, we describe a new species, Kolpochoerus millensis, based on new fossil material from the Woranso-Mille and Gona sites in the Central Afar region of Ethiopia and dated to 3.5–3.8 million years ago (Ma). Third molars of K. millensis are metrically and morphologically intermediate between the early Pliocene K. deheinzelini and earliest late Pliocene K. afarensis. It appears that K. deheinzelini, K. millensis, and K. afarensis are temporally disjunct and phenetically distinguishable parts of a single evolving lineage. The recognition of these chronospecies provides additional evidence for anagenetic evolution. It demonstrates clearly the presence of transitional forms in the fossil record. The extensive and well-dated Kolpochoerus fossil record serves as one of the best documented examples of the occurrence of phyletic evolution. Moreover, K. millensis is one of the best biochronological markers in eastern Africa for the time between 3.5 and 3.8 Ma.     

Phylogenetic relationships among sloths (Mammalia, Xenarthra, Tardigrada): the craniodental evidence

This study is undertaken in order to evaluate specific hypotheses of relationship among extant and extinct sloths (Mammalia, Xenarthra, Tardigrada). Questions of particular interest include the relationship among the three traditional family groupings of extinct ground sloths and the monophyletic or diphyletic origin of the two genera of extant tree sloths. A computer‐based cladistic investigation of the phylogenetic relationships among 33 sloth genera is performed based upon 286 osteological characteristics of the skull, lower jaw, dentition and hyoid arch. Characters are polarized via comparisons with the following successive outgroups, all members of the supraordinal grouping Edentata: the Vermilingua, or anteaters; the Cingulata, or armadillos and glyptodonts; the Palaeanodonta; and the Pholidota, or pangolins. The results of the analysis strongly corroborate the diphyly of living tree sloths, with the three‐toed sloth Bradypus positioned as the sister‐taxon to all other sloths, and the two‐toed sloth Choloepus allied with extinct members of the family Megalonychidae. These results imply that the split between the two extant sloth genera is ancient, dating back perhaps as much as 40 Myr, and that the similarities between the two taxa, including their suspensory locomotor habits, present one of the most dramatic examples of convergent evolution known among mammals. The monophyly of the three traditional ground sloth families Megatheriidae, Megalonychidae and Mylodontidae is confirmed in the present study, and the late Miocene–Pleistocene nothrotheres are shown to form a clade. It is suggested that this latter clade merits recognition as a distinct family‐level grouping, the family Nothrotheriidae. The monophyly of the Megatherioidea, a clade including members of the families Megatheriidae, Megalonychidae and Nothrotheriidae, is also supported. Within Megatherioidea, the families Nothrotheriidae and Megatheriidae form a monophyletic group called the Megatheria. The relationships within the families Megatheriidae and Mylodontidae are fully and consistently resolved, although the hypothesized scheme of relationships among the late Miocene to Pleistocene members of the mylodontid subfamily Mylodontinae differ strongly from any proposed by previous authors. Within the family Megalonychidae, Choloepus is allied to a monophyletic grouping of West Indian sloths, although the relationships within this clade are not fully resolved. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 140 , 255–305.     

Phylogenetic relationships within the Retiolitidae (Graptolithina) and a new genus, Cometograptus

A new retiolitid genus Cometograptus, restricted to the lundgreni Biozone (Late Wenlock), is characterized by a combination of primitive features such as strong transverse rods and ancora sleeve lists with seams facing out, with advanced features such as a long sicula, central, free nema and pustulose bandages. Cometograptus links two Subfamilies of the Family Retiolitidae. The Subfamily Retiolitinae is divided into redefined lineages: Pseudoretiolites, Retiolites, Paraplectograptus, whereas the Subfamily Plectograptinae is divisible into the Sokolovograptus (questionable), Gothograptus, Spinograptus, Plectograptus lineages, and Cometograptus. The Sokolovograptus group, the first retiolitids bearing ancora sleeve lists with seams facing out, did not survive the lundgreni crisis. The only survivors were Upper Wenlock retiolitids of the Gothograptus lineage. The new genus Cometograptus includes Cometograptus koreni n.gen. and n.sp., Cometograptus tomczyki n.gen. and n.sp., as well as the previously described Cometograptus nevadensis, Cometograptus marsupium and Cometograptus apoxys.     

Phylogenetic relationships within Nephtyidae (Polychaeta,Annelida)

Ravara, A., Wiklund, H., Cunha, M. R. & Pleijel, F. (2010). Phylogenetic relationships within Nephtyidae (Polychaeta, Annelida). —Zoologica Scripta, 39, 394–405. We present the first phylogeny of nephtyids, a common, soft‐bottom living polychaete family comprising five genera and over 100 species. Characters used to distinguish nephtyid genera are a matter of controversy and considerable confusion remains as to the generic delineations. The phylogeny is estimated with molecular data from the mitochondrial genes cytochrome oxidase I and 16S rDNA, the nuclear genes 18S rDNA and 28S rDNA and morphological data. The results reveal two well‐supported major clades, corresponding in part to the two main genera of the family, Aglaophamus and Nephtys. The species Nephtys pulchra and Nephtys australiensis are transferred to Aglaophamus, and new diagnoses for the genera are provided. Dentinephtys is synonymized with Nephtys, and Nephtys cornuta is sister to the remaining nephtyids and is referred to the new genus Bipalponephtys, together with Nephtys danida and Micronephthys neotena. Micronephthys is sister to Nephtys and Inermonephtys is of uncertain position.     

Phylogenetic relationships within the turacos (Musophagidae)

Cytochrome b sequences were used to investigate both the systematic position of the Musophagidae and the species relationships within the family. Phylogenetic analyses (neighbour-joining, maximum likelihood and maximum parsimony) supported the hypothesis that the Musophagidae are more closely related to the cuckoos, parrots and the Hoatzin than the gamebirds. Within the family, three major clades are evident that correspond to the three subfamilies generally recognized. The 'grey turacos' and the turacin-bearing turacos form two separate monophyletic groups. Corythaixoides leucogaster appears to be basal within the subfamily Criniferinae (the 'grey turacos'). This analysis yields a hypothesis for the controversy surrounding the position of Gallirex porphyreolophus and Tauraco johnstoni, which appear to be closely related and basal to the other turacin-bearing turacos. The Musophaga species are placed within the Tauraco clade and appear to be specialized forms of typical turacos. The superspecies persa forms a monophyletic group, within which T. hartlaubi falls. This is an association that has not been suggested previously.     

The differentiation of bunodont Listriodontinae (Mammalia,Suidae) of Africa: new data from Kalodirr and Moruorot,Kenya

The early Miocene sites of Moruorot and Kalodirr (Kenya, 17.5 Myr) have yielded a rich collection of mammals. New listriodont material from these localities, including a complete skull and a partial mandible, provide long awaited information on cranial features of early bunodont Listriodontinae. The evolution and systematics of the group are highly debated, especially regarding its first representatives. The new material described here sheds light on the differentiation of bunodont Listriodontinae in Africa and clarifies the systematics of the group. The first phylogenetic analysis of the Listriodontinae is here performed and supports close relationships between Kubanochoerus and a clade (Eurolistriodon, Listriodon). Lopholistriodon is the most basal representative of the listriodontine clade. These first results stress the role of the African continent in the biogeographical history of the Listriodontinae. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 157 , 653–678.     

Ploughing behaviour of Babyrousa babyrussa, (Suidae, Mammalia) suggests a scent-marking function

A unique form of behaviour,'ploughing behaviour', was studied in experiments carried out on 13 babirusa, three adult males, two sub-adult males, five adult females and three sub-adult females. Ploughing behaviour was observed when individual animals were introduced singly into empty sand-filled enclosures at Antwerp Zoo. The animal put its snout into the sand to such a depth that the sand was just in front of its eyes, whereupon it knelt and slid forward on to its chest. The head and chest of the animal were thereby pushed forward through the sand and canted left and right alternately. Ploughing behaviour was almost exclusively performed by adult males, the periods of longest duration being seen either in the enclosure of another male or in a freshly cleaned enclosure. The copious amounts of saliva which were produced as foam at the sides of the mouth prior to ploughing had disappeared by the end of this activity. This supports the idea that ploughing by the babirusa has a scent-marking function. The adult female did not show ploughing behaviour.     

Phylogenetic relationships within the Archiloa genus complex (Proseriata,Monocelididae)

Of the seven genera which we have recognised within the Archiloa genus complex sensu Karling (1966) the cosmopolitan genus Archilina is the most primitive and is characterised only by plesiomorphic characters, and has to be considered paraphyletic. All other species of the Archiloa genus complex are hypothesized to be derived from Archilina-like ancestors through different evolutionary lineages. One lineage led to the genera Archiloa, Inaloa, Archilopsis and Monocelopsis, taxa found in the Atlantic and the Mediterranean. These genera are monophyletic and their relationships are analyzed. The genera Mesoda (Brazil) and Tajikina (Northern Pacific) can be considered as two other separate lineages. Similarly, within what we now consider as the genus Archilina different lineages can be recognized in different regions.     

Phylogenetic relationships of vespertilionid genera (Mammalia: Chiroptera) as revealed by karyological analysis

Banded karyotypes of 50 species belonging to 23 genera were analyzed. The diploid chromosome numbers ranged from 26 to 50. For karyotypic comparison we used a 44 chromosomes karyotype, consisting of 4 metacentric and 17 acrocentric autosomes, as “basic karyotype”. Almost all of its 25 autosomal arms could be identified in each individual karyotype. In 8 chromosomes, i. e. 1/2, 7, 11, 12, 13, 15, 23 and X, small inversions were detected. As a result, each of the chromosomes mentioned occurs in two states which differ slightly in their banding patterns. These were used as character states in the cladistic analysis together with other chromosomal rearrangements. The implications drawn from the cladogram obtained are: The Miniopterinae clearly belong to the Vespertilionidae but are the first to branch off from the common stem. The tribe Myotini should be raised to the rank of a subfamily. Within the largest subfamily Vespertilioninae, one autapomorphic chromosomal character was found for each of the tribes Vespertilionini and Pipistrellini. In addition, both tribes are distinguished from the other Vespertilioninae tribes by two synapomorphic features. These results allow for the first time an unequivocal classification of the systematically difficult “pipistrelloid” species. The species of the genus Pipistrellus (sensu Hill and Harrison 1987) are spread over the Pipistrelllni and Vespertilionini. We therefore suggest the splitting of this heterogenous genus into at least four genera. Only the members of the previous subgenus Pipistrellus constitute the genus Pipistrellus and belong to the Pipistrellini. The previous subgenera Hypsugo, Vespadelus and Falsistrellus, given generic rank in some recent studies, belong to the tribe Vespertilionini and are not closely related to Pipistrellus. For the genera Eptesicus and Hesperoptenus, which belong neither to the Vespertilionini nor to the Pipistrellini, the tribe Eptesicini was established. The phylogenetic relations of this tribe and the status of the presumably polyphyletic tribe “Nycticeiini” could not be solved.     

Phylogenetic relationships and evolution of pulmonate gastropods (Mollusca): new insights from increased taxon sampling

Phylogenetic relationships among higher clades of pulmonate gastropods are reconstructed based on a data set including one nuclear marker (complete ribosomal 18S) and two mitochondrial markers (partial ribosomal 16S and Cytochrome oxidase I) for a total of 96 species. Sequences for 66 of these species are new to science, with a special emphasis on sampling the Ellobiidae, Onchidiidae, and Veronicellidae. Important results include the monophyly of Systellommatophora (Onchidiidae and Veronicellidae) as well as the monophyly of Ellobiidae (including Trimusculus, Otina, and Smeagol). Relationships within Ellobiidae, Onchidiidae, and Veronicellidae are evaluated here for the first time using molecular data. Present results are compared with those from the recent literature, and the current knowledge of phylogenetic relationships among pulmonate gastropods is reviewed: despite many efforts, deep nodes are still uncertain. Identification uncertainties about early fossils of pulmonates are reviewed. Impacts of those phylogenetic and fossil record uncertainties on our understanding of the macro-evolutionary history of pulmonates, especially transitions between aquatic and terrestrial habitats, are discussed.     

Phylogenetic relationships within laticaudine sea snakes (Elapidae)

The sea snake subfamily Laticaudinae consists of a single genus with eight named species, based on morphological characters. We used microsatellite and mitochondrial DNA (mtDNA) data to clarify the adaptive radiation of these oviparous sea snakes in the South Pacific, with special reference to New Caledonia and Vanuatu. A mitochondrial DNA data set (ND4 gene 793 bp) was obtained from 345 individuals of the five species of Laticauda sp. sea snakes endemic to the region. Maximum likelihood and Bayesian approaches yielded the same optimal tree topology, identifying two major clades (yellow-banded and blue-banded sea snakes). Although all laticaudine sea snakes rely on small islands as oviposition sites, the two lineages differ in their use of marine vs. terrestrial habitats. A highly aquatic species (Laticauda laticaudata) shows a strong pattern of genetic isolation by distance, implying that the patchy distribution of terrestrial habitats has had little impact on gene flow. The more terrestrial clade (Laticauda colubrina, Laticauda frontalis, Laticauda guineai, Laticauda saintgironsi) shows stronger geographic differentiation in allelic frequencies, associated with island groups rather than with geographic distance. Microsatellites and mtDNA suggest that L. frontalis (restricted to Vanuatu) represents a recent founder-induced speciation event, from allopatric migrants of the New Caledonian taxon L. saintgironsi. A major divergence in speciation patterns between the two major clades of laticaudine snakes thus correlates with (and perhaps, is driven by) differences in the importance of terrestrial habitats in the species' ecology.     

Late Miocene Microstonyx remains (Suidae, Mammalia) from Northern China

Several large suid cranial remains attributed to Microstonyx major are part of a new Hipparion Fauna collection from the Hezheng area, Northern China. The new material confirms the presence of Microstonyx in the late Miocene of the area. The Chinese form belongs to a small-sized eastern population with reduced premolar row and clear sexual bimodality. Statistical comparison shows that Microstonyx major was a polymorphic species and reinforces recognition of Hippopotamodon as a separate genus, defined by relatively stout premolars resulting from a different underlying pattern of allometric growth. The presence of Microstonyx in North China and the distinct suid assemblage that lived there suggest biogeographic connections between Northern China and Western Eurasia in contrast to isolation from Southern China and the Indian subcontinent. The suid fauna of the late Miocene of Northern China seems to have been restricted to the later, more humid phase represented by the Red Clay faunas.     

New remains of Egatochoerus jaegeri (Mammalia,Suoidea) from the late Eocene of Peninsular Thailand

Abstract: We report here additional remains referred to Egatochoerus jaegeri from the late Eocene locality of Ban Mark in the Krabi basin, Thailand. The new material described, comprising upper and lower cheek teeth, deciduous premolars and partial cranial remains, makes E. jaegeri the best‐documented Eocene representative of Old World Suoidea at present. Detailed study and comparison of their cheek teeth structure reveal a homogeneity of the molar crest and groove patterns of Old World and New World Palaeogene suoids.     

A new species of Celebochoerus (Suidae,Mammalia) from the Philippines and the paleobiogeography of the genus Celebochoerus Hooijer, 1948

Celebochoerus is a unique suid having extremely large upper tusks, and which was to date only known from the Pliocene-Pleistocene of Sulawesi Island in Indonesia. Here, we report on the discovery of a canine fragment referable to Celebochoerus from the Cagayan Valley of Luzon, Northern Philippines. We name a new species, Celebochoerus cagayanensis nov. sp., which differs from the Sulawesi species Celebochoerus heekereni in having mesial and distal enamel bands on the upper canines. We see these characteristics as symplesiomorphic in suids and propose a migration route from the Philippines to Sulawesi, possibly out of Taiwan, which would have occurred independently from the better known Pleistocene migration route from India into Java.     

Impact of increased character sampling on the phylogeny of Cetartiodactyla (Mammalia): combined analysis including fossils

The phylogenetic position of Cetacea (whales, dolphins and porpoises) is an important exemplar problem for combined data parsimony analyses because the clade is ancient and includes many well‐known and relatively complete fossil species. We combined data for 71 terminal taxa (43 extinct/28 extant) to test where Cetacea fits within Cetartiodactyla, and where various fossil hoofed mammals (e.g., ?entelodonts, “?anthracotheriids” and ?mesonychians) are positioned. We scored 635 phenotypic characters (osteology, dentition, soft tissue, behavior), approximately three times the number of characters in the last major analysis of this clade, and combined these with > 40 000 molecular characters, including new data from 10 genes. The analysis supported a topology consistent with the majority of recently published molecular studies. Cetacea was the extant sister taxon of Hippopotamidae, followed successively by Ruminantia, Suina and Camelidae. Several extinct taxa were phylogenetically unstable, upsetting resolution of the strict consensus and limiting branch support, but the positions of several key fossils were consistently resolved. The wholly extinct ?Mesonychia was more closely related to Cetacea than was any “artiodactylan.”“?Anthracotheriids” were paraphyletic, and, with the exception of one species, were more closely related to Hippopotamidae than to any other living taxon. The total evidence analysis overturned a highly nested position for Moschus supported by molecular data alone. The character partition that could be scored for the fossil taxa (osteological and dental characters) included more informative characters than most molecular partitions in our analysis, and had the fewest missing data. The osteological–dental data alone, however, did not support inclusion of cetaceans within crown “Artiodactyla.” Recently discovered ankle bones from fossil whales reinforced the monophyly of Cetartiodactyla but provided no particular evidence of derived similarities between hippopotamids and fossil cetaceans that were not shared with other “artiodactylans”. © The Willi Hennig Society 2007.     

Phylogenetic analysis of the tribe Bovini (Mammalia: Artiodactyla)

A matrix of 57 (mainly cranial) characters and 32 taxa of fossil and Recent Bovini (buffaloes, bison and cattle) has been analysed using the parsimony program HENNIG86. Among the best established results are the exclusion of Parabos , polyphyly of Leptobos , monophyly of the Bos sensu lato + buffaloes group (a clade including all Recent Bovini), probable monophyly of the Bubalina and Syncerina, and the close relationship between bison and yak. Some other interesting questions raised include the apparent absence of a close link between Pliocene African bovines (except "Leptobos" syrticus ) and later African buffaloes, and the possible monophyly of Pelorovis oldowayensis+Bos sensu lato .