Extinct Order Research Articles

Grazing-induced losses of biodiversity affect the transpiration of an arid ecosystem

Degradation processes often lead to species loss. Such losses would impact on ecosystem functioning depending on the extinction order and the functional and structural aspects of species. For the Patagonian arid steppe, we used a simulation model to study the effects of species loss on the rate and variability (i.e. stability) of transpiration as a key attribute of ecosystem functioning. We addressed (1) the differences between the overgrazing extinction order and other potential orders, and (2) the role of biomass abundance, biomass distribution, and functional diversity on the effect of species loss due to overgrazing. We considered a community composed of ten species which were assigned an order of extinction due to overgrazing based on their preference by livestock. We performed four model simulations to test for overgrazing effects through different combinations of species loss, and reductions of biomass and functional diversity. In general, transpiration rate and variability were positively associated to species richness and remained fairly constant until half the species were lost by overgrazing. The extinction order by overgrazing was the most conservative of all possible orders. The amount of biomass was more important than functional diversity in accounting for the impacts of species richness on transpiration. Our results suggest that, to prevent Patagonian steppes from shifting to stable, low-production systems (by overgrazing), maintaining community biomass is more important than preserving species richness or species functional diversity.

The enigmatic Pennsylvanian arachnids Areomartus ovatus and Vratislavia silesica (Trigonotarbida)

Abstract Areomartus ovatus Petrunkevitch 1913, from the Pennsylvanian (Kanawah Formation; Bashkirian?) of Cotton Hill, Fayette County, West Virginia, USA is redescribed. Originally placed in the family Eophrynidae of the extinct arachnid order Trigonotarbida, it lacks unequivocal eophrynid features. Nevertheless, Areomartus Petrunkevitch 1913 was used as the type genus of a now superfluous eophrynid subfamily Areomartinae Petrunkevitch 1955. The present revision suggests that too much emphasis was placed on the primary diagnostic character of Areomartus, hexagonal fields across the carapace, in a rather poorly preserved and incomplete specimen. Areomartus ovatus is thus removed from Eophrynidae and treated as Trigonotarbida incertae sedis. Vratislavia silesica (Romer 1878) from the Pennsylvanian (Langsettian?) of Klodzko (formally Glatz) in Silesia, Poland is another problematic eophrynid. The holotype is believed lost, and thus interpretations rely on published figures. Opisthosomal morphology suggests t...

Attention in neglect and extinction: Assessing the degree of correspondence between visual and auditory impairments using matched tasks

Claims have been made for associated degrees of impairment on both visual and auditory performance in unilateral neglect and extinction. Since this evidence is primarily based on different tests in each modality, it is difficult to properly quantify the degree of association between performance in vision and audition. The current study compares visual and auditory extinction and temporal order judgments (TOJs) in two cases with clinical visual neglect. Stimuli in both modalities were precisely matched in their temporal and spatial parameters. The results reveal a mixed pattern of association between different auditory tests and their visual counterparts. This suggests that associations between visual and auditory neglect can occur but these are neither obligatory nor pervasive. Instead, our data support models of spatial impairment in neglect and extinction that acknowledge differences in the contribution of spatial information to performance in each modality in responses to changing task demands.

Biodiversity‐ecosystem function research: Insights gained from streams

AbstractIn this review, we address the extent to which stream ecology has contributed to biodiversity‐ecosystem function (BEF) theory and empirical testing. BEF research first targeted the implications of the ongoing loss of biodiversity for ecosystems and humans. Terrestrial ecology has played a leading role in this field, whereas the contribution of riverine science to the debate has been more limited. Nevertheless, a considerable merit of stream ecology has been to consider a wide range of ecological groups (riparian litter producers, aquatic micro‐fungi, macroinvertebrates, and fishes). Through a meta‐analysis of these unique data, we show that the relative importance of species numberversusassemblage composition increases as we go towards higher trophic levels. Whether this pattern is general or specific to stream ecosystems needs to be evaluated through cross‐ecosystem comparisons looking more closely at mechanistic processes. It is evident from stream studies that trophic and non‐trophic (e.g. facilitation) interactions govern the functional consequences of biodiversity. These studies also indicate that richness‐function relationships are altered by a multitude of factors, such as evenness, non‐taxonomic diversity (genetic/phenotypic diversity), species extinction order, the environmental context, as well as experimental setups. This review highlights the relevance of stream ecology to BEF research. Copyright © 2009 John Wiley & Sons, Ltd.

The evolutionary history of the extinct ratite moa and New Zealand Neogene paleogeography.

The ratite moa (Aves: Dinornithiformes) were a speciose group of massive graviportal avian herbivores that dominated the New Zealand (NZ) ecosystem until their extinction approximately 600 years ago. The phylogeny and evolutionary history of this morphologically diverse order has remained controversial since their initial description in 1839. We synthesize mitochondrial phylogenetic information from 263 subfossil moa specimens from across NZ with morphological, ecological, and new geological data to create the first comprehensive phylogeny, taxonomy, and evolutionary timeframe for all of the species of an extinct order. We also present an important new geological/paleogeographical model of late Cenozoic NZ, which suggests that terrestrial biota on the North and South Island landmasses were isolated for most of the past 20-30 Ma. The data reveal that the patterns of genetic diversity within and between different moa clades reflect a complex history following a major marine transgression in the Oligocene, affected by marine barriers, tectonic activity, and glacial cycles. Surprisingly, the remarkable morphological radiation of moa appears to have occurred much more recently than previous early Miocene (ca. 15 Ma) estimates, and was coincident with the accelerated uplift of the Southern Alps just ca. 5-8.5 Ma. Together with recent fossil evidence, these data suggest that the recent evolutionary history of nearly all of the iconic NZ terrestrial biota occurred principally on just the South Island.

Ligogramma wichita, A New Species of Caloneurodea (Polyneoptera: Orthopterida) from the Lower Permian Wellington Formation of Noble County, Oklahoma

The extinct polyneopterous order Caloneurodea Handlirsch, which includes more than 20 species, has been found in Eurasia and North America, and ranges from the Upper Carboniferous to the Upper Permian. North American records are most numerous from the Lower Permian Wellington Formation of Kansas and Oklahoma. The genus Ligogramma, provisionally assigned by Béthoux et al., 2004, to either Caloneurodea or Orthoptera, is herein redescribed and placed in the Caloneurodea, based on the discovery of a new species, Ligogramma wichita, described from a specimen collected from Noble County, Oklahoma. This brings the total number of Caloneurodea currently known from the Wellington Formation to eight species.

Habitat destruction and the extinction debt revisited: The Allee effect

Habitat destruction, often caused by anthropogenic disturbance, can lead to the extinction of species at an unprecedented rate. It is important, therefore, to consider habitat destruction when assessing population viability. Another factor often ignored in population viability analysis, is the Allee effect that adds to the risk of populations already on the verge of extinction. Understanding the Allee effect on species dynamics and response to habitat destruction has intrinsic value in conservation prioritization. Here, the Allee effect was considered in a multi-species hierarchical competition model. Results showed that species persistence declines dramatically due to the Allee effect, and certain species become more susceptible to habitat destruction than others. Two extinction orders emerged under habitat destruction: either the best competitor becomes extinct first or the best colonizer first. The extinction debt and order, as well as the time lag between habitat destruction and species extinction, were found to be determined by species abundance and the intensity of the Allee effect.

An Enigmatic New Genus of Biarmohymenid from the Early Permian Wellington Formation of Noble County, Oklahoma (Palaeodictyopterida: Diaphanopterodea)

A new genus and species of the extinct Paleozoic insect order Diaphanopterodea (Palaeodictyopterida) is described and figured from the Early Permian (Artinskian) Wellington Formation of Noble County, Oklahoma. Anomalohymen dochmus, new genus and species, is most similar to Biarmohymen bardense Zalessky from the Early Permian (Kungurian) of Tshekarda in Russia. The two genera share the proximal coalescence of M and CuA along with a generally reduced venation. Rather than erect another monogeneric family, we here include Anomalohymen in the Biarmohymenidae, emending the diagnosis of the family, providing a key to the constituent genera, and extending the biogeographic and temporal range of the lineage.

Bioenergetics and inter-individual variation in physiological capacities in a relict mammal – the Monito del Monte (Dromiciops gliroides)

In evolutionary physiology, studies of inter-individual variation (i.e. repeatability) in functional capacities are valuable as they indicate - within populations - what attributes could respond to natural selection. Although repeatability and quantitative genetics of physiological traits in energy metabolism of eutherian mammals have been well characterized, few or no studies have been performed on marsupials. We studied the repeatability (i.e. intraclass correlation coefficient, tau) of bioenergetics for Monito del Monte (Dromiciops gliroides), the sole living representative of an otherwise extinct marsupial order (Microbiotheria). We measured resting metabolic rate as CO(2) production (V(CO(2))) and O(2) consumption (V(O(2))) simultaneously, together with minimum thermal conductance (C), evaporative water loss (EWL) and respiratory quotient (RQ), in a sample of ca. 20 individuals. Our results suggest that D. gliroides exhibits poor control of body temperature (T(b)), with a thermal amplitude of ca. 10 degrees C in normothermia. As a consequence, repeatability of T(b) and metabolic rate (either as V(CO(2)) or V(O(2))) were relatively low (tau(T)(b)=0.25+/-0.04, tau(VCO2)=0.14+/-0.03, tau(V)(O2)=0.24+/-0.02, jackknife estimations of standard errors). Thermal conductance exhibited near-zero or negative repeatability and was lower than expected for marsupials. However, we found significant repeatability for RQ and EWL (tau=0.32+/-0.03 and 0.49+/-0.09, respectively). In general, these results suggest that Monito del Monte exhibits some ;reptilian' physiological characteristics. The relatively low repeatability of physiological variables, which otherwise exhibit large inter-individual and genetic variance in eutherian mammals, suggests that these capacities do not exhibit evolutionary potential in the ancient order Microbiotheria.

Quantifying the randomness of extinctions

Extinctions occur either randomly or in a more deterministic and predictable manner, with certain characteristics making some species more vulnerable to (local) extinction than others. Although the quantification of extinction randomness would better our understanding of the extinction causes and increase the predictability of future species losses, few quantification methods are currently available. To this purpose, we propose two indices based on a comparison of an a priori (expected) extinction series with an observed one. Whereas the first index requires data on the order of extinctions, the second index is only concerned with which species went extinct and which did not. Using a model for generating extinction data, we tested both indices successfully for accordance with the robustness prerequisites. Index outputs were furthermore unaffected by species richness, apart from decreased variation with rising species numbers. Because of its independence of non‐extinct species and its focus on extinction sequences, the first randomness index seems especially useful for use in paleontological and paleo‐ecological research. The second index is likely a good tool to study shorter term extinctions, for which the extinction order is often not known and for which the comparison with species that did persist is of greater interest. We use a real dataset to illustrate this. Finally, we discuss how it is possible to expand the use of this index toward identifying previously unknown extinction‐promoting species characteristics, and toward a credible assessment of the extinction risk posed by global change.

Eocene archaeohyracids (Mammalia: Notoungulata: Hegetotheria) from the Puna, northwest Argentina

A new genus and species of basal hegetothere mammal, Punahyrax bondesioi, is described from the middle-late? Eocene Geste Formation of northwestern (Catamarca and Salta provinces) Argentina. The new species is based on isolated teeth and mandibles and represents the first well-identified archaeohyracid from northwestern Argentina, and the earliest extra-Patagonian record of the family. It is characterized by its small-size and a short talonid on the molars. Though still poorly documented, this new taxon may provide key-data for the problem of the origin and basal of hegetotheres phylogeny. These fossils show the importance of northwestern Argentina (Puna area) in the early evolution of the extinct order Notoungulata and the poor state of our knowledge there.

Abundance patterns in multi-species communities exposed to habitat destruction

Habitat destruction resulting from human activity is a serious threat to biodiversity. The model developed by Tilman et al. [Tilman, D., May, R.M., Lehman, C.L., Nowak, M.A., 1994. Habitat destruction and the extinction debt. Nature 371, 65–66] has become an important tool for analyzing persistence of species in habitats under destruction. However, most analysis and applications of this model have been limited to the studies of species richness and the order of extinction. In this paper, we address other important issues related to succession of species abundances. We are interested in how the abundance ranking (i.e., the ranking of species according to their relative abundances), the rank–abundance curve and the community diversity alter in habitats under destruction. We treat analytically the model of Tilman et al. and investigate three different scenarios. We consider that before destruction: (i) best competitors are most abundant; (ii) all species are equally abundant; (iii) poor competitors are most abundant. In each case, we have derived explicit expressions for equilibrium species abundances depending on proportion of destroyed sites. Then we follow analytically alteration in the initial abundance ranking, show complex patterns of succession of species abundances and consider transformations in the rank–abundance curve. We demonstrate patterns of self-organization in abundance distributions emerging as a response to habitat destruction. We show non-monotonic dependence of community diversity and community evenness on proportion of destroyed sites.

Global Change and Invasive Species: The Demonic Duo

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Centipede systematics: progress and problems*

Breakthroughs in centipede systematics over the past 25 years have included: a stable morphology-based cladogram for ordinal interrelationships that is largely congruent with well-sampled nuclear ribosomal genes; the discovery of mid Palaeozoic crown-group fossils, including Silurian-Devonian stem-group Scutigeromorpha and an extinct order in the Middle Devonian; and, a web-based catalogue of all centipede species globally. Challenges include species delimitation in several groups, conflict between different kinds of molecular data (nuclear coding genes versus ribosomal genes), the inter-familial relationships and classification of the Geophilomorpha in particular, and effecting a synthesis between microanatomical studies of selected ‘model’ species and dense taxonomic sampling in numerical phylogenetic analyses.

Erdtmanispermum juncalense sp. nov., a new species of the extinct order Erdtmanithecales from the Early Cretaceous (probably Berriasian) of Portugal

Well-preserved lignitic seeds are described from Early Cretaceous sediments (probably Berriasian) exposed in the Vale Painho clay pit complex near the small village of Juncal in the Estremadura region, Western Portugal. The seeds are small, weakly triangular in transverse section, about 1.05–1.5 mm long and 0.75–1.1 mm broad, with elongated distinctly pointed micropylar area at the apex and rounded base. The seeds have clear affinity with the extinct Erdtmanispermum (Erdtmanithecales) and are assigned to a new species Erdtmanispermum juncalense based on the distinct rugulate outer envelope and the ovoid to guttiform outline. The description of the mesofossils provided here is the first report of Erdtmanithecales seeds from the Early Cretaceous of Portugal and adds to our knowledge of the diversity and geographic distribution of Cretaceous Eucommiidites-producing plants.

RESPONSE OF COMPLEX FOOD WEBS TO REALISTIC EXTINCTION SEQUENCES

Although an ecosystem's response to biodiversity loss depends on the order in which species are lost, the extinction sequences generally used to explore such responses in food webs have been ecologically unrealistic. We investigate how several extinction orders affect the minimum number of secondary extinctions expected within pelagic food webs from 34 temperate freshwater lakes. An ecologically plausible extinction order is derived from the geographically nested pattern of species composition among the lakes and is corroborated by species' pH tolerances. Simulations suggest that lake communities are remarkably robust to this realistic extinction order and highly sensitive to the reverse sequence of species loss. This sensitivity is not well explained by the known sensitivity of networks to the loss of highly connected species but appears to be better explained by our observation that trophic specialists preferentially consume widely distributed species at low risk of extinction. Our results highlight an important aspect of community organization that may help to maintain biodiversity amidst changing environments.

Jurassic Cladocera (Crustacea, Branchiopoda) with a description of an extinct Mesozoic order

This paper describes extinct Jurassic Cladocera (Crustacea: Branchiopoda) from four well‐known palaeontological sites. Leptodorosida zherikhini sp. nov., gen. nov. from Ust’‐Baley (Lower Jurassic) belongs to an extinct family, Leptodorosididae fam. nov., and a new order, the Cryptopoda ordo nov. This order differs from the Haplopoda and the Onychopoda in having serially‐similar filtering limbs with valves completely covering the post‐cephalic body. Cryptopoda differs from the Anomopoda and Ctenopoda in having antennae II with both exopod and endopod possessing four segments. Segments 2–4 of the exopod (and perhaps the endopod) possess numerous setae. A second cryptopod, Leposida ponomarenkoi sp. nov., gen. nov., was found in Chalunikha and Unda (Uppermost Jurassic). So, the extinct Crypopoda existed for at least 25 million years during the Jurassic. Our finding of an extinct order possessing characters intermediate between recent cladoceran orders provides fossil evidence for cladoceran monophyly. I also describe a new ctenopod, Smirnovidaphnia smirnovi sp. nov., gen. nov. from Ust’‐Baley as a member of the family Sididae. It belongs to the tribe Sidini of the subfamily Sidinae, but differs from recent genera of this tribe in having numerous setae on the second exopod segment. Archedaphnia testacea Smirnov, 1971, previously described from Novospasskoye (Lower‐Middle Jurassic), is apparently a ctenopod, and, most probably, a member of Smirnovidaphnia gen. nov. Finally, I found claws, presumably belonging to unknown cladocerans, from the Ust’‐Baley and four other localities from the Lower to Upper Jurassic. I conclude that cladocerans were present and common in Mesozoic waters.

Convergent morphology in small spiral worm tubes (‘ Spirorbis ’) and its palaeoenvironmental implications

Calcareous tube-worms generally identified as Spirorbis range from Ordovician to Recent, often profusely encrusting shells and other substrates. Whereas Recent Spirorbis is a polychaete annelid, details of tube structure in pre-Cretaceous ‘ Spirorbis ’ suggest affinities with the Microconchida, an extinct order of possible lophophorates. Although characteristically Palaeozoic, microconchid tube-worms survived the Permian mass extinction before being replaced in late Mesozoic ecosystems by true Spirorbis . Recent Spirorbis is stenohaline but spirorbiform microconchids also colonized freshwater, brackish and hypersaline environments during the Devonian–Triassic. Anomalies in the palaeoenvironmental distributions of fossil ‘ Spirorbis ’ are explained with the recognition of this striking convergence between microconchids and true Spirorbis .

Diversification of the Neoselachii (Chondrichthyes) during the Jurassic and Cretaceous

The Neoselachii are a monophyletic group including all of the extant sharks and rays. They underwent rapid diversification throughout the Jurassic and Cretaceous, going from low-diversity assemblages of members of extinct orders in the Late Triassic to diverse assemblages containing representatives of most extant clades by the end of the Cretaceous. The known fossil record of Mesozoic neoselachians is composed largely of isolated teeth, with articulated skeletal remains being known from a limited number of sites. The small tooth size of a large proportion of neoselachians, including almost all taxa in existence prior to the mid Cretaceous, led to very poor representation in older publications. Their state of knowledge has improved dramatically since 1970 with the increased use of bulk sampling for isolated dental remains. Despite this, the high proportion of Lazarus taxa from some stages suggests that the state of knowledge is still intermittent. Increase in assemblage diversity throughout the Jurassic and Cretaceous suggests that radiation events resulted in real and dramatic increases in diversity, and that the perceived diversification is not an artifact of poor knowledge. Cladogenesis inferred from the fossil record typically compares more favorably with divergence predicted from molecular analysis, where Batoidea form a discrete basal clade, than with divergence predicted from morphological analysis, where Batoidea are considered a derived crown group within the Squalea. The timing of diversification events is discussed in light of the known fossil record, cladistically generated divergence times, and the paleoenvironmental distribution of faunas.

A new ‘South American ungulate’ (Mammalia: Litopterna) from the Eocene of the Antarctic Peninsula

Abstract Notolophus arquinotiensis , a new genus and species of the family Sparnotheriodontidae (Mammalia, Litopterna), is represented by several isolated teeth from the shallow-marine sediments of the La Meseta Formation (late Early-Late Eocene) of Seymour Island, Antarctic Peninsula, which have also yielded the youngest known sudamericids and marsupials. The new taxon belongs to the extinct order of ‘South American native ungulate’ Litopterna characterized by the convergence of the later forms with the equids and camelids. Notolophus arquinotiensis shows closest relationships with Victorlemoinea from the Itaboraian (middle Palaeocene) of Brazil and Riochican-Vacan (late Palaeocene-early Eocene) of Patagonia, Argentina. Although still poorly documented, this new taxon shows that the early Palaeogene Antarctic faunas might provide key data concerning the problems of the origin, diversity and basal phylogeny of some of the ‘South American ungulates’ (Litopterna). This new taxon shows the importance of Antarctica in the early evolution of the ungulates and illustrates our poor state of knowledge.