North American Taxa Research Articles

Feeding biomechanics of Late Triassic metoposaurids (Amphibia: Temnospondyli): a 3D finite element analysis approach.

The Late Triassic freshwater ecosystems were occupied by different tetrapod groups including large-sized anamniotes, such as metoposaurids. Most members of this group of temnospondyls acquired gigantic sizes (up to 5 m long) with a nearly worldwide distribution. The paleoecology of metoposaurids is controversial; they have been historically considered passive, bottom-dwelling animals, waiting for prey on the bottom of rivers and lakes, or they have been suggested to be active mid-water feeders. The present study aims to expand upon the paleoecological interpretations of these animals using 3D finite element analyses (FEA). Skulls from two taxa, Metoposaurus krasiejowensis, a gigantic taxon from Europe, and Apachesaurus gregorii, a non-gigantic taxon from North America, were analyzed under different biomechanical scenarios. Both 3D models of the skulls were scaled to allow comparisons between them and reveal that the general stress distribution pattern found in both taxa is clearly similar in all scenarios. In light of our results, both previous hypotheses about the paleoecology of these animals can be partly merged: metoposaurids probably were ambush and active predators, but not the top predators of these aquatic environments. The FEA results demonstrate that they were particularly efficient at bilateral biting, and together with their characteristically anteropositioned orbits, optimal for an ambush strategy. Nonetheless, the results also show that these animals were capable of lateral strikes of the head, suggesting active hunting of prey. Regarding the important skull size differences between the taxa analyzed, our results suggest that the size reduction in the North American taxon could be related to drastic environmental changes or the increase of competitors. The size reduction might have helped them expand into new ecological niches, but they likely remained fully aquatic, as are all other metoposaurids.

Circumscription of species in the Hodophilus foetens complex (Clavariaceae, Agaricales) in Europe

Four European Hodophilus species with an odour similar to naphthalene, a strong unpleasant odour similar to that of mothballs, are recognized based on sequence and/or morphological data. The traditional concept defines Ho. foetens as the only Hodophilus species with a naphthalene odour in Europe. This name is now assigned to one of the studied species based on morphological examination of the holotype specimen. A recently collected specimen is proposed as the epitype. The other three species with a naphthalene odour are described here as new: Ho. pallidus, Ho. subfoetens and Ho. tenuicystidiatus. They are distinguishable in the field based on a combination of lamellae number and colour of basidiomata. All four species are grouped in the Ho. foetens superclade, one of two superclades, together with the Ho. micaceus superclade, in the genus Hodophilus. All are different species from North American taxa with a naphthalene-like odour recognised in a previous study. The Ho. foetens superclade also includes one species identified as Ho. atropunctus that does not have a distinctive odour. The type collection of Ho. albofloccipes, a recently described European species with a naphthalene odour, is placed together with some collections without a distinctive odour in the Ho. micaceus superclade.

Physa acutaDraparnaud, 1805 Should be Treated as a Native of North America, Not Europe

ABSTRACT Physa acuta (Gastropoda: Heterobranchia: Physidae) is a freshwater snail commonly found in North American rivers, streams and ponds. Despite its widespread distribution across the United States, it is generally regarded as an invasive species. As a result, P. acuta receives no attention during conservation management inventories. However, data suggest that P. acuta may be a native to North America rather than to Europe, where it was first described. First, the fossil record in Europe lacks P. acuta, whereas North America is home to numerous fossils of members of the acuta species group. Second, breeding studies among P. acuta and North American taxa from the acuta species group show no evidence of pre- or postzygotic isolation. Third, investigations of reproductive anatomy between P. acuta and other nominal species of the acuta species group are indistinguishable, leading investigators to synonymize taxa. Finally, phylogenetic data do not support the distinction of P. acuta from its North America...

The oldest Cenozoic mammal fauna of Europe: implication of the Hainin reference fauna for mammalian evolution and dispersals during the Paleocene

The mammal fauna of Hainin is particularly interesting as the oldest in the Cenozoic of Europe, and the earliest reference level (MP1–5) of the mammalian biochronological scale for the European Palaeogene. This paper summarizes the mammal taxa discovered in the fauna, presents an analysis of the fauna as a whole (relative abundance and species richness), and describes four new eutherians: Belgoryctes thaleri gen. et sp. nov., Eurolestes dupuisi gen. et sp. nov., Quadratodon sigei gen. et sp. nov. and Cingulodon magioncaldai gen. et sp. nov. The assemblage is relatively small (about 400 dental specimens), characterized by a high diversity and abundance of small insectivorous species and very low abundance of ‘plesiadapiforms’ and ‘condylarths’. By comparison with younger European Paleocene faunas, ‘condylarths’ and ‘plesiadapiforms’ became more and more abundant and diverse through the Paleocene but collapsed at the Paleocene–Eocene Boundary. ‘Proteutherians’ declined steadily, while multituberculates remained diverse, although the early Paleocene was populated mainly by Kogaionidae whereas the late Paleocene was dominated by Neoplagiaulacidae. The palaeoecology of Hainin is deduced from the mammal assemblage: the local environment was likely a forested area. Stratigraphically, the Hainin deposits are most likely of late Danian age, and biochronologically its fauna represents a partial equivalent of the North American Torrejonian Land Mammal Age. When compared to younger Paleocene faunas of Europe, the composition of the Hainin fauna reveals that a relatively important intercontinental dispersal of mammals occurred around the Danian–Selandian boundary, roughly corresponding to the Torrejonian–Tiffanian boundary. This dispersal is marked by the arrival in Europe of typically North American taxa such as arctocyonids, plesiadapids and neoplagiaulacid multituberculates. Additional exchanges of lesser magnitude probably also occurred around the Selandian–Thanetian boundary (i.e. during the Tiffanian), although the evidence is less compelling and mainly concerns the plesiadapids Chiromyoides and Plesiadapis.http://zoobank.org/urn:lsid:zoobank.org:pub:A240BAE2-7446-4DBD-A597-7BEFE58447DF

Asynchronous diversification of snakes in the North American warm deserts

AbstractAimWe quantify the degree to which co‐distributed snakes across the Cochise Filter Barrier (CFB) have a shared history of population divergence and estimate the timing of divergence for each taxon pair.LocationNorth America.MethodsA single locus dataset was collected (n = 747 individuals) for 12 snake taxon pairs. Phylogeographical structure was estimated for each taxon. Redundancy analyses were used to assess the importance of geographical distance, climate and putative barriers to gene flow in structuring genetic diversity. Hierarchical approximate Bayesian computation was used to estimate the magnitude of synchronicity in divergence times across a well‐documented phylogeographical barrier. Lastly, gene divergence and population divergence times were estimated using multiple methods.ResultsThere is substantial phylogeographical structure in many of the snake taxa, particularly at the CFB. A model containing distance, climate and barriers explained the greatest amount of genetic variation in nearly all taxa. When each variable was examined separately, climate explained the most variation. The hABC model testing indicates that there is overwhelming support for asynchronous phylogeographical histories within these co‐distributed taxa. Estimated divergence times range throughout the Quaternary and Neogene.Main ConclusionsWe demonstrate that the 12 snake taxon pairs studied here have diversified within the desert Southwest forming distinct Sonoran and Chihuahuan populations, illustrating the importance of this region in driving diversification in North American taxa. Although these groups exhibit the same pattern of lineage formation, there is strong support for asynchronous diversification and little concordance in divergence time estimates.

Fruits of Juglandaceae from the Eocene of South America

Abstract Specimens of a new fruit genus and species, Alatonucula ignis, from the early Eocene Laguna del Hunco flora of Chubut, Patagonia, Argentina, have characteristics consistent with assignment to Juglandaceae. Each fossil fruit consists of a nutlet with an attached wing that varies from unlobed to trilobed. One specimen clearly shows that the nutlet has a single locule partially subdivided into four chambers; its counterpart contains a four-lobed locule cast. The basally partitioned locule with lobed seed indicates that Alatonucula can be placed within Juglandaceae; the overall structure of the fruits suggests affinities to subfamily Engelhardioideae, which typically have fruits consisting of a nutlet attached to a trilobed wing. Parsimony analyses of a morphological matrix for extant and fossil Juglandaceae revised from a previously published study demonstrate that 1) Alatonucula groups with Engelhardioideae; and 2) Paleooreomunnea, an Eocene North American taxon that includes a fruit type with a tr...

Systematics of the ectomycorrhizal genus Lactarius in the Rocky Mountain alpine zone

Lactarius (Russulales) is an important component of ectomycorrhizal fungal communities in cold-dominated contiguous arctic and disjunct alpine habitats where it associates primarily with Betula, Dryas and Salix. However, little is known of this genus in the central and southern Rocky Mountain alpine zone (3000–3900 m) of North America. Molecular phylogenetic analyses of nuc rDNA ITS1-5.8S-ITS2 (ITS barcode) and the second largest subunit of the RNA polymerase II gene (RPB2) partial sequences in conjunction with detailed morphological examination confirm at least six species occurring above treeline. Most have intercontinental distributions in North America and Eurasia according to molecular comparison with type material and collections from Europe, Fennoscandia, Svalbard and Alaska. Rocky Mountain collections of L. lanceolatus (subgenus Russularia), along with the type from Alaska are paraphyletic with respect to L. aurantiacus and North American taxa L. luculentus and L. luculentus v. laetus. Rocky Mountain collections of L. nanus, L. glyciosmus, L. repraesentaneus and L. salicis-reticulatae (subgenus Piperites) all form clades with European material from type localities and other arctic-alpine habitats. The arctic-alpine L. pseudouvidus/L. brunneoviolaceus group appears to be a complex containing additional taxa. North American material originally described as part of this group is well-separated phylogenetically and is described here as L. pallidomarginatus sp. nov. Lactarius lanceolatus, L. nanus and L. salicis-reticulatae appear largely restricted to arctic-alpine habitats with Salix. Lactarius glyciosmus and L. repraesentaneus occur in arctic-alpine, subalpine and boreal habitats with Betula and also Picea and possibly Salix for the latter. Species distributions are hypothesized to be shaped by host ranges, glaciation and long distance dispersal.

A New Large Hyainailourine from the Bartonian of Europe and Its Bearings on the Evolution and Ecology of Massive Hyaenodonts (Mammalia).

We describe a new large-sized species of hypercarnivorous hyainailourine–Kerberos langebadreae gen. & sp. nov.–from the Bartonian (MP16) locality of Montespieu (Tarn, France). These specimens consist of a skull, two hemimandibles and several hind limb elements (fibula, astragalus, calcaneum, metatarsals, and phalanges). Size estimates suggest K. langebadreae may have weighed up to 140 kg, revealing this species as the largest carnivorous mammal in Europe at that time. Besides its very large size, K. langebadreae possesses an interesting combination of primitive and derived features. The distinctive skull morphology of K. langebadreae reflects a powerful bite force. The postcranial elements, which are rarely associated with hyainailourine specimens, indicate an animal capable of a plantigrade stance and adapted for terrestrial locomotion. We performed the first phylogenetic analysis of hyainailourines to determine the systematic position of K. langebadreae and to understand the evolution of the group that includes other massive carnivores. The analysis demonstrates that Hemipsalodon, a North American taxon, is a hyainailourine and is closely related to European Paroxyaena. Based on this analysis we hypothesize the biogeographic history of the Hyainailourinae. The group appeared in Africa with a first migration to Europe during the Bartonian that likely included the ancestors of Kerberos, Paroxyaena and Hemipsalodon, which further dispersed into North America at this time. We propose that the hyainailourines dispersed into Europe also during the Priabonian. These migrants have no ecological equivalent in Europe during these intervals and likely did not conflict with the endemic hyaenodont proviverrines. The discovery of K. langebadreae shows that large body size appears early in the evolution of hyainailourines. Surprisingly, the late Miocene Hyainailouros shares a more recent common ancestor with small-bodied hyainailourines (below 15 kg). Finally, our study supports a close relationship between the Hyainailourinae and Apterodontinae and we propose the new clade: Hyainailouridae.

Taxonomic changes in the treehopper genera Helonica Ball, Telamona Fitch, and Palonica Ball (Hemiptera: Membracidae: Smiliinae: Telamonini).

Nomenclatural changes within the treehopper tribe Telamonini are made as follows based on an examination of the type material of several species: the genus Helonica Ball is a junior synonym of Telamona Fitch, n. syn.; Telamona excelsa (Fairmaire), n. comb., with n. syn. T. unicolor Fitch; T. projecta Butler is reinstated from synonymy as a valid taxon for the North American taxa historically placed in Helonica; and Palonica albidorsata (Fowler) from Mexico, n. comb., is reinstated from synonymy based on morphological differences with T. excelsa and T. projecta. Lectotype designations are clarified for T. fasciata and T. unicolor based on specimens in the New York State Museum (NYSM). As a result of this work, the tribe Telamonini contains 68 species in 10 genera, the genus Palonica contains 7 species, and the genus Telamona contains 29 species.

Cortinarius koldingensis—a new species of Cortinarius, subgenus Phlegmacium related to Cortinarius sulfurinus

Cortinarius koldingensis is described as a new species based on several collections from a small area in Denmark. Sequence data from the ITS marker places it in the Sulfurini group of the large Calochroi clade of Cortinarius subgenus Phlegmacium, along with C. sulfurinus and two North American taxa. It is phylogenetically distinct from the other species in the Sulfurini and differs from C. sulfurinus by several deviating morphological characteristics. The species has been collected on several occasions over the last 15 years from only one Danish locality. Despite extensive molecular screening of numerous possible conspecific specimens, including holotype and comparison with all publicly available ITS sequence data from specimens and environmental DNA alike, no match with specimens from elsewhere has been encountered, and we hypothesize that the species is rare in Europe.

Eocene fossils and the early evolution of frogmouths (Podargiformes): further specimens of Masillapodargus and a comparison with Fluvioviridavis

New fossils of the podargiform Masillapodargus longipes are described from the early Eocene German fossil site Messel. Previously unreported skeletal details of this species confirm its assignment to Podargiformes (frogmouths), and especially the wing and pectoral girdle bones exhibit close similarities to crown group Podargiformes. Here, I show that the postcranial skeletal morphology of Masillapodargus is quite different from that of the early Eocene North American taxon Fluvioviridavis, for which podargiform affinities were recently proposed. With regard to the morphologies of the humerus and the coracoid, Fluvioviridavis more closely resembles Steatornithiformes (oilbirds). These may be plesiomorphic similarities, if Steatornithiformes and Podargiformes are sister taxa as recently suggested. Both podargiform affinities of Fluvioviridavis, as well as a sister group relationship between Podargiformes and Steatornithiformes, are, however, only weakly based. A well-founded classification of Fluvioviridavis depends on a better understanding of the basal divergences within extant Strisores, the clade including “caprimulgiform” and apodiform birds, which remain controversial.

New material from a huge specimen of "Anteophthalmosuchus" cf. "escuchae" (Goniopholididae) from the Albian of Andorra (Teruel, Spain): Phylogenetic implications

In 2011 the partial skeleton of a goniopholidid crocodylomorph was recovered in the ENDESA coal mine Mina Corta Barrabasa (Escucha Formation, lower Albian), located in the municipality of Andorra (Teruel, Spain). This new goniopholidid material is represented by abundant postcranial and fragmentary cranial bones. The study of these remains coincides with a recent description in 2013 of at least two new species of goniopholidids in the palaeontological site of Mina Santa Maria in Arino (Teruel), also in the Escucha Formation. These species are Anteophthalmosuchus escuchae, Hulkepholis plotos and an undetermined goniopholidid, AR-1-3422. In the present paper, we describe the postcranial and cranial bones of the goniopholidid from Mina Corta Barrabasa and compare it with the species from Mina Santa Maria. For the first time, we include the taxa from the Escucha Formation in a phylogenetic analysis to establish their relationships within Goniopholididae, adding to what is known of the goniopholidid fossil assemblages from this time interval. The results indicate that the specimen from Mina Corta Barrabasa is closely related to Anteophthalmosuchus escuchae and may be the same species. Together with Hulkepholis plotos and other taxa from England and Belgium, these taxa form an endemic European clade. The Escucha Fm. goniopholidids are the youngest Eurasian members of the group and may be the youngest globally, depending on how North American taxa are eventually resolved.

Late Palaeocene eusuchian remains from Mont de Berru, France, and the origin of the alligatoroidDiplocynodon

Crocodilian remains from the late Palaeocene continental locality of Mont de Berru (Marne, France) offer the opportunity to reassess the taxonomic identity of the oldest diplocynodontid from Europe. Owing to significant morphological differences from previously described species of Diplocynodon, which include the presence of a splenial symphysis, a new species, Diplocynodon remensis sp. nov., is erected here. Its inclusion in a phylogenetic framework for Eusuchia leads to its positioning as a derived member of diplocynodontids. Diplocynodontidae are viewed as a basal alligatoroid taxon, and, because morphological affinities with the Late Cretaceous−early Eocene North American genus Borealosuchus were mentioned in earlier studies, a comparison amongst D. remensis sp. nov., Leidyosuchus, and Borealosuchus spp. is presented. Although D. remensis sp. nov. is the geologically oldest diplocynodontid, according to our results, it is not the phylogenetically most primitive. Other morphological discrepancies are highlighted, indicating that the topology recovered here is only tentative. From a biogeographical point of view, the appearance of Diplocynodon in Europe prior to the Palaeocene/Eocene boundary indicates that it did not disperse with North American taxa that reached Europe around the time of the Palaeocene-Eocene thermal maximum (PETM). Therefore, a pre-PETM dispersal from North America at the same times as other vertebrates with clear North American affinities also occurring in the Palaeocene of Europe cannot be excluded. The description of D. remensis sp. nov. adds substantial new, albeit conflicting, information, highlighting the need for a better phylogenetic framework with a revision of other critical taxa (Menatalligator, Borealosuchus) from the Palaeocene of Europe and North America. © 2014 The Linnean Society of London

The cranial anatomy of the neornithischian dinosaur Thescelosaurus neglectus.

Though the dinosaur Thescelosaurus neglectus was first described in 1913 and is known from the relatively fossiliferous Lance and Hell Creek formations in the Western Interior Basin of North America, the cranial anatomy of this species remains poorly understood. The only cranial material confidently referred to this species are three fragmentary bones preserved with the paratype, hindering attempts to understand the systematic relationships of this taxon within Neornithischia. Here the cranial anatomy of T. neglectus is fully described for the first time based on two specimens that include well-preserved cranial material (NCSM 15728 and TLAM.BA.2014.027.0001). Visual inspection of exposed cranial elements of these specimens is supplemented by detailed CT data from NCSM 15728 that enabled the examination of otherwise unexposed surfaces, facilitating a complete description of the cranial anatomy of this species. The skull of T. neglectus displays a unique combination of plesiomorphic and apomorphic traits. The premaxillary and ‘cheek’ tooth morphologies are relatively derived, though less so than the condition seen in basal iguanodontians, suggesting that the high tooth count present in the premaxillae, maxillae, and dentaries may be related to the extreme elongation of the skull of this species rather than a retention of the plesiomorphic condition. The morphology of the braincase most closely resembles the iguanodontians Dryosaurus and Dysalotosaurus, especially with regard to the morphology of the prootic. One autapomorphic feature is recognized for the first time, along with several additional cranial features that differentiate this species from the closely related and contemporaneous Thescelosaurus assiniboiensis. Published phylogenetic hypotheses of neornithischian dinosaur relationships often differ in the placement of the North American taxon Parksosaurus, with some recovering a close relationship with Thescelosaurus and others with the South American taxon Gasparinisaura, but never both at the same time. The new morphological observations presented herein, combined with re-examination of the holotype of Parksosaurus, suggest that Parksosaurus shares a closer relationship with Thescelosaurus than with Gasparinisaura, and that many of the features previously cited to support a relationship with the latter taxon are either also present in Thescelosaurus, are artifacts of preservation, or are the result of incomplete preparation and inaccurate interpretation of specimens. Additionally, the overall morphology of the skull and lower jaws of both Thescelosaurus and Parksosaurus also closely resemble the Asian taxa Changchunsaurus and Haya, though the interrelationships of these taxa have yet to be tested in a phylogenetic analysis that includes these new morphological data for T. neglectus.

What became of Hystrix?

AbstractHystrix Moench was a perennial genus of the Triticeae. Its members differed from those of other genera in the tribe in lacking glumes. The type species is H. patula Moench, a North American taxon. When it became accepted that H. patula should be included in Elymus, Hystrix could not be used as a generic name. The problem became how to treat the other species that had been included in Hystrix. Hystrix patula, like many other species of Elymus, has the StH genomic composition but H. coreana (Honda) Ohwi, H. californica (Bol.) Kuntze, H. duthiei (Stapf) Bor ssp. duthiei, and H. duthiei ssp. longearistata have the NsXm genomic composition that is associated with Leymus. Using genomic in situ hybridization analysis, we showed that H. komarovii (Roshev.) Ohwi has an NsEe genomic composition, a combination not known from any other species. Hystrix sibirica (Trautv.) Kuntze and H. duthiei ssp. japonica are included in Leymus on morphological grounds. The status of H. kunlunensis K. S. Hao is not clear. In this paper, we summarize our results and those of others concerning what is now known and the problems that remain concerning the species that used to be included in Hystrix.

Phylogenetic diversity of true morels (Morchella), the main edible non-timber product from native Patagonian forests of Argentina

Morchella species are edible fungi in high demand and therefore command high prices in world markets. Phenotypic-based identification at the species-level remains inadequate because of their complex life cycles, minor differences and plasticity of morphological characteristics between species, and the lack of agreement between scientific and common names. In Patagonia–Argentina, morels are associated with native forests of Austrocedrus chilensis (Cordilleran or Chilean cypress) and Nothofagus antarctica (ñire) and several exotic conifers that were introduced from western North America. Little is known about their taxonomy and phylogenetic relationships with other species in the genus. This work focused on the identification of collections of Morchella from Patagonia and their phylogenetic relationships with other species from the Northern Hemisphere. The comparison was made by analysis of DNA sequences obtained from four loci: the nuclear ribosomal internal transcribed spacer region (ITS) and the partial RNA polymerase I gene (RPB1) for the complete collection; and ITS, RPB1, RNA polymerase II gene (RPB2), and translation elongation factor (EF1-α) for the species-rich Elata Subclade. Analyses of individual and combined data sets revealed that Patagonian morels belong to the Elata Clade and comprised three strongly supported species-level lineages from both Patagonian native forest, and exotic trees introduced from western North America. One lineage was identified as Morchella frustrata phylogenetic species Mel-2, which is known from the USA and Canada. The second lineage, which appeared to be ‘fire-adapted’, was identified as Morchella septimelata phylogenetic species (Mel-7), which is also known from the USA. This species was collected from burned native forests mainly composed of A. chilensis and N. antarctica but also Pseudotsuga menziesii (Mirb.) Blanco, which is native to western North America. The phylogenetic analyses suggested that the third species from Patagonia was nested within the species-rich Elata Subclade and represents a new species-level lineage (informally designated Mel-37) within Elata Clade. The present collections from Patagonia constitute the southernmost latitude from which Morchella has been reported to date. The identification of two Argentine morels as North American taxa is therefore a remarkable biogeographic pattern. In view of the hypothesis that the Elata Clade originated in western North America, we speculate that at least two of the lineages colonized South America from North America via long distance dispersal, migration or, more likely, they were introduced with the exotic tree species that they were collected near.

Phylogenetic Systematics of the Genus <I>Mertensia</I> (Boraginaceae)

The diversity of Mertensia (Boraginaceae), a monophyletic group that is widely distributed in Asia, Beringia, North America, and circumboreal locales, has presented considerable taxonomic difficulties. Phylogeny reconstructions based on DNA sequence data from eleven chloroplast (cp) regions were used to infer evolutionary lineages, address problematic taxonomic circumscriptions, test hypotheses of relationships, and discuss variation of morphological characters in Mertensia (Boraginaceae). Phylogenetic analyses using maximum parsimony, maximum likelihood, and Bayesian inference consistently recovered three clades that largely correspond to geography. One clade consisted of a grade of Asian taxa, a Beringian subclade, and a circumboreal subclade. A second clade consisted of the Beringian M. rivularis and was weakly to moderately supported as sister to a third clade, which consisted only of North American taxa. Although we recovered weak support for many of the deeper nodes in the North American clade, our results provided moderate to strong support for 13 subclades. Hypothesis testing using the Shimodaira-Hasegawa (SH) and Approximately Unbiased (AU) tests rejected several earlier hypotheses of relationships except for three models of relationships suggested by Williams: (1) section Mertensia sensu Williams; (2) M. oreophila and M. oblongifolia var. nevadensis sensu Williams; and (3) M. arizonica var. arizonica, M. arizonica var. subnuda, M. grahamii, and M. toyabensis sensu Williams. In the latter three cases, alternative phylogenetic hypotheses were rejected by the AU test but not by the SH test. The North American clade includes M. ciliata, M. lanceolata, M. oblongifolia, and M. viridis, for which broad circumscriptions by some authors have been especially problematic. Our phylogenetic results recovered these taxa as polyphyletic and hypothesis tests rejected the monophyly of each of these species when treated broadly. We recommend narrow circumscriptions for each of these taxa and suggest further studies of the oblongifolia complex. Our results represent the first and most comprehensive molecular phylogeny to date for Mertensia. We propose to emend the section Stenhammaria to include Asian, Beringian, and circumboreal taxa. New combinations include: Mertensia grahamii, Mertensia longipedunculata, Mertensia ovata var. caelestina, and Mertensia parvifolia.

Megafauna: giant beasts of Pleistocene South America

Megafauna: giant beasts of Pleistocene South America

First evidence of the tooth eruption sequence of the upper jaw in Hyaenodon (Hyaenodontidae, Mammalia) and new information on the ontogenetic development of its dentition

Juvenile material with the main focus on the upper jaw of the fossil predator Hyaenodon was evaluated to study the tooth eruption sequence and to examine the ontogeny of its dentition in detail. The comparison in size of milk to permanent teeth indicates a growth rate of 12–16 % in Hyaenodon. The thin section of a deciduous canine of a North American taxon shows four dental rings. Based on the knowledge of recent carnivores, this implies an age of 3–4 years in the last stage of tooth eruption and thus a long juvenile phase. The mandibles ascertained the most recent established tooth eruption sequence for North American and European species. For the first time ever, juvenile material from Asia is documented and interpreted. This study likewise shows a difference in the sequence of the upper jaw: the first upper premolar erupts before the first upper molar in North American species, whereas the European taxa show an earlier eruption of the first upper molar. This fact further confirms the divergence between the Hyaenodon lineages from North America and Europe.

Systematics, biogeography, and character evolution of Sparganium (Typhaceae): Diversification of a widespread, aquatic lineage

Sparganium (Typhaceae) is a genus of aquatic monocots containing ±14 species, with flowers aggregated in unisexual, spherical heads, and habit ranging from floating to emergent. Sparganium presents an opportunity to investigate diversification, character evolution, and biogeographical relationships in a widespread temperate genus of aquatic monocots. We present a fossil-calibrated, molecular phylogeny of Sparganium based on analysis of two chloroplast and two nuclear markers. Within this framework, we examine character evolution in both habit and stigma number and infer the ancestral area and biogeographic history of the genus. • Sequence data from two cpDNA and two nDNA markers were analyzed using maximum parsimony, maximum likelihood, and Bayesian inference. We used the program BEAST to simultaneously estimate phylogeny and divergence times, S-DIVA and Lagrange for biogeographical reconstruction, and BayesTraits to examine locule number and habit evolution. • Two major clades were recovered with strong support: one composed of S. erectum and S. eurycarpum; and the other containing all remaining Sparganium. We realigned the subgenera to conform to these clades. Divergence time analysis suggests a Miocene crown origin but Pliocene diversification. Importantly, the floating-leaved habit has arisen multiple times in the genus, from emergent ancestors-contrary to past hypotheses. • Cooling trends during the Tertiary are correlated with the isolation of temperate Eurasian and North American taxa. Vicariance, long-distance dispersal, and habitat specialization are proposed as mechanisms for Sparganium diversification.