Brachiopod Species Research Articles

Reappraisal of the brachiopod Acrotreta socialis von Seebach, 1865: clarifying 150 years of confusion

The acrotretide Acrotreta socialis von Seebach, 1865 has suffered a long and tumultuous history since its original description from the middle Cambrian (Guzhangian Stage) Andrarum Limestone of Bornholm, Denmark. Uncertainties regarding key morphological characters have resulted in numerous revisions and redescriptions of the species with much of the taxonomic shuffling occurring before the mid-20th century. A major problem with the early documentation of acrotretide brachiopods is that many species were described in the days before the advent of the Scanning Electron Microscope (SEM), resulting in dubious interpretations of significant morphological characteristics, like the position of the pedicle foramen and the internal morphology of both valves. A detailed revision of Acrotreta species resulted in the proposal that the genus is restricted solely to the Ordovician with the Bornholm acrotretide species subsequently left floating in taxonomic limbo. Recent taxonomic suggestions have been provisional, awaiting morphological information based on type or topotype material. The examination of topotype material in addition to supplementary material collected from southern Sweden has elucidated many of the previous ambiguous morphological characteristics of the species confirming that the original description was based on more than one brachiopod species. The new morphological information acquired here has resulted in the erection of a new acrotretid genus, Clupeafumosus gen. nov., to accommodate the material previously described as Acrotreta socialis. Co-occurring with Clupeafumosus socialis in southern Sweden is another new acrotretide brachiopod, Monophthalma andersoni sp. nov., which is additionally described.

Correlative Relationships Between Carbon- and Oxygen-Isotope Records in Two Cool-Temperate Brachiopod Species off Otsuchi Bay, Northeastern Japan

We present high-resolution, three-dimensional carbon (δ13C)- and oxygen (δO)-isotope compositions from calcite shells of two modern brachiopod species (Terebratulina crossei and Terebratalia coreanica) and their correlative relationships. δ13C and δ18O values from the secondary shell layer, which constitutes the main body of a brachiopod shell, are in and/or out of the range of δ13C and δ18O values of calcite precipitated in isotopic equilibrium with ambient seawater (equilibrium calcite). The δC and δ18O values of samples from the outermost part of the secondary shell layer show positive correlations. The values of high-growth-rate portions are less than those of low-growth-rate portions; these results are ascribed to a kinetic isotope fractionation effect. Metabolic influences are identified in the isotopic compositions of the low-growth-rate portions for T. coreanica, resulting in decreases in δ13C values compared with those of equilibrium calcite. We illustrate the effects of kinetic isotope fractionation and metabolism on the isotopic compositions of brachiopod shell calcite, which vary among shell portions within a single shell, as well as between the two species. However, appropriate selection of brachiopod taxa and shell portions that reflect the isotopic composition of ambient seawater enables their use as a reliable paleoenvironmental proxy.

Deep-water brachiopod assemblage from the Middle Miocene of Kralice nad Oslavou, Moravia, southeastern Czech Republic

Eight brachiopod species, i.e. Novocrania sp., Cryptopora lovisati (Dreger, 1911), “Terebratula” sp., Megathiris detruncata (Gmelin, 1791), Argyrotheca cuneata (Risso, 1826), Joania cordata (Risso, 1826), Megerlia truncata (Linnaeus, 1767), and Platidia anomioides (Scacchi and Philippi, 1844), have been identified in the Middle Miocene deposits of Kralice nad Oslavou, Moravia, Czech Republic. The species C. lovisati and P. anomioides dominate the studied assemblage, while others are very rare. Novocrania, C. lovisati and M. truncata are reported for the first time from the Moravian part of the Carpathian Foredeep. In species composition, the assemblage from Kralice resembles other Middle Miocene Paratehyan assemblages, interpreted as shallow water, but the dominance of C. lovisati and P. anomioides makes it clearly different, indicating an environment deeper than 100m.

A new morphometric model in distinguishing two closely related extinct brachiopod species

Pseudoatrypa (Atrypida, Brachiopoda) are extinct Paleozoic brachiopods that are the closest relatives of the modern brachiopods, rhynchonellids. Two Paleozoic brachiopod species were qualitatively distinguished based on close examination of phenotypic characters and traditional morphometrics. These species were recovered for the first time from the Givetian localities of Traverse Group of Michigan. The efficacy of geometric morphometric analyses in discriminating species has been proven for various organisms, but rarely studies have been performed in distinguishing brachiopod species. The advanced morphometric model developed here using the Procrustes-based landmark method is based on the analysis of valve shape in two extinct brachiopod species: Pseudoatrypa lineata and Pseudoatrypa devoniana. Results from quantitative analyses reinforce the qualitative identifications of the two species. The application of this method on four different orientations (dorsal, ventral, posterior and anterior regions) of the brachiopods permits the two species to be clearly separated, and this study proposes that the model can be effectively used for future identification and distinction of fossil species. Additionally, this study will aid biologists, paleontologists and neontologists in making appropriate advancement in systematic studies and further assist with gauging biodiversity congruously.

Brachiopods, biostratigraphy, and correlation of the Permian marine deposits of Mongolia

Six horizons and 11 brachiopod zones are distinguished in the Permian of the Khangai-Khentei (Boreal) and South Mongolian (Tethys) marine basins of Mongolia on the base of monographic study of brachiopods and literary data on other faunal groups. The distinguished in the Permian basins of Mongolia biostratons are correlated with zonal brachiopod scales of neighboring regions of Northeast Asia. Possible bio-geographical relations of the Mongolian Permian marine basins and channels of brachiopods are analyzed. Forty-five brachiopod species are figured including species, which were first described from Mongolia, zonal index species and typical representatives of zonal assemblage.

Quantitative analysis strengthens qualitative assessment: a case study of Devonian brachiopod species

Species recognition attributed to the brachiopod family Atrypidae is evaluated based on qualitative and quantified morphological characters. I identified two brachiopod species—Pseudoatrypa lineata and Pseudoatrypa devoniana—from a rich assemblage of brachiopods recovered from the middle Devonian Genshaw Formation of the Traverse Group. Qualitative examination suggested that the former had fine-medium-sized ribbing, a narrow hinge line, widened anterior, moderately steep mid-anterior fold, domal shaped dorsal valve, and an inflated ventral valve in contrast to the coarse ribbing, widened hinge line, narrow anterior, gentle mid-anterior fold, arched-shape dorsal valve, and flat ventral valve of the latter. The shell outline appears rounded for P. lineata and elongated for P. devoniana. Quantitative assessment of the morphological characters on the dorsal, ventral, anterior, and posterior regions of the valves of the two species using geometric morphometric and statistical analyses suggests that the morphologies of the two species are considerably different (P \( \ll \) 0.01). Thus, qualitative differences between the two atrypid species were further corroborated by quantitative results. This emphasizes the fact that these two species of Pseudoatrypa were indeed different from each other. This study highlights the necessity of incorporating quantified morphological characters to successfully investigate the taxonomic distinctness of fossil invertebrates to the species level.

Late Mississippian (Early Carboniferous) brachiopods from the western Daba Mountains, central China

Qiao L. & Shen S.Z., September 2012. Late Mississippian (Early Carboniferous) brachiopods from the western Daba Mountains, central China. Alcheringa 36, 287–309. ISSN 0311–5518. Fifteen brachiopod species in 12 genera are described for the first time from four intervals in the middle and upper parts of the Zhanpo Formation at the Huoyanxi section near Zhenba in the western Daba Mountains, southern Shaanxi, central China. The Zhenba brachiopod fauna is dominated by diverse and abundant species of Productida, together with some species of Athyridida, Orthida, Orthotetida and Spiriferida. It ranges from late Viséan to Serpukhovian in age based on the presence of Gigantoproductus species in association with diagnostic foraminifera and conodonts. This fauna generally shows palaeobiogeographical links with the palaeoequatorial realm, including Western Europe, the Moscow Basin, the Ural Mountains, Japan, eastern Tibet and South and North China. Its closest palaeobiogeographical affinity is with South China assemblages rather than those of North and Northwest China, therefore, indicating that the Zhenba area was palaeogeographically close to the South China Block and relatively far from the blocks in Northwest China (e.g., the Qilian Mountains and Qaidam Basin, Kunlun Mountains, Tarim Basin and Tianshan Mountains) during the late Viséan–Serpukhovian.

Systematics and palaeoecology of Changhsingian (Late Permian) Ambocoeliidae brachiopods from South China and implications for the end-Permian mass extinction

Weihong He, G.R. Shi, Yang Zhang, Tinglu Yang, Fei Teng.& Shunbao Wu, December 2012. Systematics and palaeoecology of Changhsingian (Late Permian) Ambocoeliidae brachiopods from South China and implications for the end-Permian mass extinction. Alcheringa 36, 515–530. ISSN 0311-5518. Four Ambocoeliidae brachiopod species including one new species (Crurithyris tazawai sp. nov., Crurithyris sp., Paracrurithyris pygmaea and Attenuatella mengi) are described from the Changhsingian (Late Permian) deep-water facies of South China. Analysis of the morphology, palaeoecology and palaeogeographical and temporal distributions of these species revealed that the presence of a delthyrium and/or the micro-ornaments among three of the four species (Crurithyris tazawai sp. nov., Paracrurithyris pygmaea and Attenuatella mengi) favoured an epifaunal (epiphytic) lifestyle. Morphological differences suggest that Paracrurithyris pygmaea may have been more effective metabolically in forming the shell compared with Attenuatella mengi and Crurithyris tazawai. The temporal and palaeogeographical distribution of Attenuatella suggests that A. mengi inhabited cool or cold deep waters. Both Crurithyris tazawai and Attenuatella mengi disappeared earlier in the stratigraphic record than Paracrurithyis pygmaea during the Permian–Triassic mass extinction. These differences in timing of extinction, morphology and palaeogeographical distributions suggest that oxygen deficiency and trophic resource limitation (a consequence of the changing composition of marine phytoplankton in the seas) may have contributed to the end-Permian mass extinction.

Predation on two brachiopods, Joania cordata and Argyrotheca cuneata, from an offshore reef in the Tyrrhenian Sea

Predator holes in empty shells of Joania cordata and Argyrotheca cuneata (Brachiopoda: Megathyrididae) collected in the marine protected area “Secche di Tor Paterno”, central Tyrrhenian Sea, Italy (41°35′N–12°20′E, at depths of 20–28 m), were analyzed. Predation intensity was low but appreciable, with the more common species J. cordata preyed on more frequently (6.7 %) than A. cuneata (3.8 %). Three main types of holes were recognized: (1) cylindrical drill holes with a circular outline, (2) larger irregular holes with a jagged outline, and (3) small holes at the bottom of depressions in the shell. They were probably produced by muricid gastropods, crabs, and Foraminifera, respectively. The large, irregular holes were the most common type in both brachiopod species. Evidence for predator selectivity with respect to which valve, the position of the hole on the valve, and the size of the brachiopod with respect to those available was assessed. The ventral valve, the postero-medial portions of both valves, and larger (J. cordata) or medium-sized (A. cuneata) shells were more frequently holed.

Symposium summary: Palaeoecology

news and update ISSN 1948‐6596 sample points (hooks) and hundreds of millions of observations (fish caught). By stitching together several such datasets, and after correcting for variability in the data such as geographically un‐ evenly distributed effort, Tittensor and Worm were able to detect changes in range. They found generally similar patterns across the Atlantic, In‐ dian, and Pacific oceans, showing an apparent ef‐ fect of life‐history. Fishes that grew more slowly and to larger size and spawned in aggregations, such as the bluefin tuna (Thunnus thynnus and T. orientalis), showed decreases in range size; the range of Thunnus thynnus has contracted almost entirely from the South Atlantic, and populations are fractioning in the Pacific. In contrast, fishes that grow faster to smaller maximum size, such as the albacore tuna (Thunnus alalunga) generally have shown no change or an increase in range. Whether changing ocean climate or exploitation provide a more likely explanation is currently un‐ der investigation. Thus, we find consensus in the results of Davidson et al. and Tittensor and Worm in predicting, if human activities don’t change, an ecological extinction of the marine megafauna that echoes the extinction of the terrestrial megafauna from the Americas thousands of years ago. While in many ways we are beginning to see parallels between marine and terrestrial systems, it would be heartening to see a difference in this respect. Michael N Dawson School of Natural Sciences, University of California at Merced, USA. email: mdawson@ucmerced.edu; http:// mnd.ucmerced.edu References Barnosky, A.D., Matzke, N., Tomiya, S., Wogan, G.O.U., Swartz, B., Quental, T.B., Marshall, C., McGuire, J.L., Lindsey, E.L., Maguire, K.C., Mersey, B. & Ferrer, E.A. (2011) Has the Earth’s sixth mass extinction already arrived? Nature, 471, 51–57. Tyberghein, L., Verbruggen, H., Pauly, K., Troupin, C., Mineur, F. & De Clerck, O. (2011) Bio‐ORACLE: a global environmental dataset for marine species distribution modeling. Global Ecology and Biogeog‐ raphy, doi:10.1111/j.1466‐8238.2011.00656.x Verbruggen, H., Tyberghein, L., Pauly, K., Vlaemick, C., Van Nieuwenhuyze, K., Kooistra, W., Leliaert, F. & De Clerck, O. (2009) Macroecology meets macroevolution: evolutionary niche dynamics in the seaweed Halimeda. Global Ecology and Bio‐ geography, 18, 393‐405. Edited by Chris Burridge symposium summary Palaeoecology A contributed session at the 5th International Biogeography Society Conference – Heraklion, Greece, 7–11 January 2011 The IBS meeting is rapidly emerging as a critical meeting for those interested in paleo‐ biogeography, and in particular for those inter‐ ested in how past and present biogeographic pat‐ terns are shaped by the intersection of past envi‐ ronmental changes with ecological and evolution‐ ary processes. Paleoecology was well represented at the Crete meeting, with 25 abstracts submitted, a packed oral session, and many cross‐cutting talks. Several general themes emerged from the talks in the paleoecology session. One running theme was species niches and their shifting manifestation over time in response to new species interactions and environmental conditions . Alycia Stigall (“Using ecological niche modeling to evaluate niche stability in deep time”) applied GARP and Maxent analyses to Late Ordo‐ vician brachiopod species to show that niche con‐ servatism decreased during and after a major in‐ vasion event (the Richmondian Invasion), suggest‐ ing that species responded to invasion pressure. Jack Williams and co‐authors (“Apparent niche shifts and no‐analogue climates in eastern North America during the Late Quaternary”) tackled the problem of reconstructing ‘truncated’ niches, i.e. species’ fundamental niches for portions of envi‐ ronmental space that do not exist at present, showing that different starting assumptions re‐ sulted in very different reconstructions of species fundamental niches, and hence very different pre‐ frontiers of biogeography 3.1, 2011 — © 2011 the authors; journal compilation © 2011 The International Biogeography Society

A field-based analysis of the accuracy of niche models applied to the fossil record

The use of ecological niche modeling (ENM) to estimate the geographic ranges of species is widely employed with modern fauna and is becoming more widespread in paleontology. Herein, field validation is utilized to assess the predictive accuracy of ENM methods for Paleozoic brachiopod species. This study represents the first field validation analysis of ENM methods in the fossil record. Previously published species distributions models for 8 Late Ordovician brachiopod species from the Cincinnati, Ohio region (United States) developed using GARP (Genetic Algorithm using Rule-set Prediction) were assessed for accuracy by comparing species occurrence data from a newly available set of 18 localities with the original species distribution models. Based on this data, the statistical significance of the original model set was assessed; 18 of the 22 original models were demonstrated to be statistically significant, based on field validation. Of the 140 individual species occurrences assessed, 60.8% were accurately predicted, 9.2% exhibited over prediction, and 30% exhibited under prediction. Accurate results were more common for species modeled from the greatest number of species occurrence points. The least accurate species models developed were for eurytopic species or those for which taxonomic affinities are unclear. Results indicate that with ample outcrop, well-defined stratigraphy, and sufficient fossil occurrence data, ENM methods could be successfully applied to many intervals in Earth history.

Guadalupian (Permian) brachiopods from the Ruteh Limestone, North Iran

ABSTRACTThirty-three brachiopod species from the Guadalupian Ruteh Limestone of North Iran are here systematically described and illustrated. Brachiopods have been collected bed-by-bed along five stratigraphic sections and in one fossiliferous locality in the region between Dorud and Shirinibad in the Alborz Mountains. Four new species and one new genus are erected in the present paper: Haydenella eminens n. sp. Perigeyerella rutehiana n. sp., Martinia bassa n. sp. and Bisolcatelasma iraniana n. gen. n. sp.Quantitative biostratigraphic analysis of the brachiopod data based on the Unitary Association method (Guex, 1991) has lead to the construction of a local sequence of three discrete biozones: the Squamularia sp. B-M. bassa Biozone at the base of the formation, the H. kiangsiensis-N. (N.) asseretoi Biozone in its middle part and the R. exile-R. gemmellaroi Biozone at its top. The latter however has been recognized only in the Shirinabad section.As already envisaged for the Carboniferous and Lower Permian brachiopod faunas from North Iran, the Guadalupian fauna is comprised mostly of cosmopolitan taxa, confirming the role of the Iranian microplate as a staging-post for most of the late Palaeozoic. When compared to the younger Lopingian faunas collected in the same regions of North Iran, the Ruteh brachiopods appear significantly different, indicating a marked biotic change in the brachiopod communities across the end-Guadalupian biotic crisis.

Using ecological niche modelling to evaluate niche stability in deep time

AbstractAim To investigate relative niche stability in species responses to various types of environmental pressure (biotic and abiotic) on geological time‐scales using the fossil record.Location The case study focuses on Late Ordovician articulate brachiopods of the Cincinnati Arch in eastern North America.Methods Species niches were modelled for a suite of fossil brachiopod species based on five environmental variables inferred from sedimentary parameters using GARP and Maxent. Niche stability was assessed by comparison of (1) the degree of overlap of species distribution models developed for a time‐slice and those generated by projecting niche models of the previous time‐slice onto environmental layers of a second time‐slice using GARP and Maxent, (2) Schoener’s D statistic, and (3) the similarity of the contribution of each environmental parameter within Maxent niche models between adjacent time‐slices.Results Late Ordovician brachiopod species conserved their niches with high fidelity during intervals of gradual environmental change but responded to inter‐basinal species invasions through niche evolution. Both native and invasive species exhibited similar levels of niche evolution in the invasion and post‐invasion intervals. Niche evolution was related mostly to decreased variance within the former ecological niche parameters rather than to shifts to new ecospace.Main conclusions Although the species examined exhibited morphological stasis during the study interval, high levels of niche conservatism were observed only during intervals of gradual environmental change. Rapid environmental change, notably inter‐basinal species invasions, resulted in high levels of niche evolution among the focal taxa. Both native and invasive species responded with similar levels of niche evolution during the invasion interval and subsequent environmental reorganization. The assumption of complete niche conservatism frequently employed in ecological niche modelling (ENM) analyses to forecast or hindcast species geographical distributions is more likely to be accurate for climate change studies than for invasive species analyses over geological time‐scales.

Niche stability in Late Ordovician articulated brachiopod species before, during, and after the Richmondian Invasion

In this study, the relative niche stability of Late Ordovician articulate brachiopod species from the Cincinnati Arch was analyzed before, during, and after an immigration of extra-basinal taxa into the region, known as the Richmondian Invasion. The primary hypothesis investigated with this project is whether species preserve (via niche conservation) or alter (via niche evolution) the parameters of their ecological niche during intervals of biotic (invasive regime) vs. abiotic change (gradual environmental change). Ecological niche modeling (ENM), a process that utilizes computer-based algorithms to mathematically estimate a species ecological niche, was employed to test this hypothesis. Additionally, the efficacy of using the ENM program Maxent with fossil data was tested against a well-established ENM method (GARP). Results indicate that during intervals of gradual change, species conserved the parameters of their ecological niches to higher degrees than during intervals of ecological rapid biotic change, when niche evolution was common. Native and invasive species displayed congruent patterns of niche stability, but niche conservatism was more common in broadly adapted generalist species than ecological specialists.

Diversity Dynamics of Callovian-Albian Brachiopods in the Northern Caucasus (Northern Neo-Tethys) and a Jurassic/Cretaceous Mass Extinction

The fossil records of the Northern Caucasus (southwestern Russia) provide an exceptional opportunity to reveal the evolution of brachiopods during the Callovian-Albian time interval and to evaluate the regional evidence for a Jurassic/Cretaceous mass extinction. Stratigraphic ranges of 119 species, 52 genera, 25 families, 13 superfamilies, and 2 orders of brachiopods are considered to document the main patterns of their diversity dynamics. The total number of taxa was high in the Callovian-Oxfordian, then dropped in the Kimmeridgian, increased again in the Tithonian, decreased significantly in the Berriasian, and remained relatively low until the end of the Early Cretaceous except for a minor peak in the Barremian. Species, genera, families, and superfamilies of brachiopods declined remarkably in the Northern Caucasus in the Berriasian, which is regional evidence for a Jurassic/Cretaceous mass extinction. Both an acceleration in disappearance rate and a drop in appearance rate contributed to this collapse. Recovery began in the Valanginian-Hauterivian, but it was not completed at the level of species. Transgressions/regressions, growth of the carbonate platform, a salinity crisis, and oxygen depletion were important controls on the brachiopod diversity dynamics in the Northern Caucasus. A regressive episode around the Jurassic-Cretaceous transition seems to be a plausible cause of the relevant brachiopod decline. A comparison of changes in the total number of brachiopod taxa between the Neo-Tethys Ocean and the Alpine Tethys Ocean shows some difference, but both domains provide evidence for a Jurassic/Cretaceous mass extinction, which was less severe in the Swiss Alps and the Jura Mountains (Alpine Tethys) than in the Northern Caucasus (Neo-Tethys).

Genus-specific commensalism of the galeommatoid bivalve Koreamya arcuata (A. Adams, 1856) associated with lingulid brachiopods

We compared shell morphology and DNA sequences of the ectosymbiotic bivalves Koreamya (Montacutidae) attached to two different species of inarticulate brachiopods Lingula collected from South Korea. There are some differences in shell morphology between K. arcuata (A. Adams, 1856) attached to Lingula anatina and K. sp. attached to L. adamsi, such as shell outline, periostracum and hinge teeth. However, there are very few differences in DNA sequences of COI and ITS1 suggesting that the two forms of Koreamya are genetically conspecific. While many ectosymbiotic Galeommatoidea species have been reported to live commensally with only one host species, this study suggested that K. arcuata lives commensally with at least two species of Lingula and that its shell morphology may vary according to the host species.

Brachiopod taxa and shell portions reliably recording past ocean environments: Toward establishing a robust paleoceanographic proxy

[1] Fossils of rhynchonelliform brachiopods (marine invertebrates) constitute ∼70% of the samples used for delineating a well-known Phanerozoic trend in oxygen isotope composition (δ18O) of low-Mg calcite shells. The trend represents secular variations in temperature and/or δ18O of ancient seawater. However, the use of brachiopods as a paleoceanographic proxy is based on the presupposition that the shell calcite is precipitated in isotopic equilibrium with ambient seawater. Here, we show that high-resolution time series of the shell δ18O values along the maximum growth axes of two long-lived cool-water brachiopods are identical to, greater than, or less than those of calcite precipitated in isotopic equilibrium with ambient seawater, depending on the difference in shell growth rates. Coupled with δ18O data from subtropical and warm-temperate brachiopod species examined in our previous studies, we provide a sound framework illustrating which taxa and shell portions reliably recorded past ocean environments.

Tournaisian (Mississippian) brachiopods from the Mobarak Formation, North Iran

ABSTRACTFollowing detailed stratigraphic work on the Mississippian marlstone and bioclastic limestone of the Mobarak Formation of the Alborz Mountains in North Iran, forty-eight of the most important brachiopod taxa are here systematically described and illustrated. The ranges of the taxa are given along the Abrendan and Simeh Kuh stratigraphic sections, located north of Damgham. The examined brachiopod species date the base of the Mobarak Formation to the Tournaisian, in absence of age-diagnostic foraminifers. Change in brachiopod settling preferences indicates a shift from high energy, shallow-water settings with high nutrient supply in the lower part of the formation to quieter, soft, but not soppy substrates, with lower nutrient supply in the middle part of the Mobarak Formation. Brachiopod occurrence is instead scanty at its top. The palaeobiogeographic affinity of the Tournaisian brachiopods from North Iran indicates a closer relationship to North America, Western Europe and the Russian Platform than to cold-water Australian faunas, confirming the affinity of the other biota of the Alborz Mountains. This can be explained by the occurrence of warm surface-current gyres widely distributing brachiopod larvae across the Palaeotethys Ocean, where North Iran as other peri-Gondwanan blocks acted as staging-posts.

Detecting competition in the fossil record: Support for character displacement among Ordovician brachiopods

In an effort to further our understanding of ecosystem structure on multiple temporal and biogeographic scales, the influence of competitive interactions in an invasive setting was explored in the fossil record. Using brachiopod morphology as a proxy for niche space occupation, the external shapes of three pairs of potentially competing brachiopod species were analyzed via three-dimensional baseline shape co-ordinates. Morphology of incumbents was compared before and after the Richmondian Invasion (Late Ordovician, Illinois Basin), and for each incumbent–invader pair: it was possible to differentiate the incumbents pre- and post-invasion; the incumbent became more morphologically different from the invader; and landmarks driving the morphological differences of two of the incumbents shift away from the invader in multidimensional morphospace. These results are consistent with character displacement, which supports the hypothesis that competition played a discernable role in the brachiopod community. This suggests that the use of morphometrics and morphospace occupation could provide a valuable tool for the exploration of ecological interactions in the geologic record, potentially providing novel interpretations of the effects of competition on community structure and evolution.

A Kungurian (Early Permian) Panthalassan brachiopod fauna from Hatahoko in the Mino Belt, central Japan

Twelve brachiopod species are described from the Cisuralian (Early Permian) Kungurian horizon of a large limestone block in the Middle Jurassic accretionary complex at Hatahoko in the Mino Belt, central Japan. Most species of the Hatahoko fauna are known from the Kungurian to lowest Guadalupian (Middle Permian) of West Texas, U.S.A. The Kungurian age is also indicated by the associated conodonts in the same limestone block. The Hatahoko brachiopod fauna, as well as some other previously-reported Guadalupian brachiopod faunas, exhibits a very strong paleobiogeographical affinity with the faunas in West Texas, U.S.A. Therefore it can be interpreted as a fauna which inhabited reef-seamount complexes close to North America in the mid-equatorial region of the Panthalassa in the late Early Permian, rifted westwards thousands of kilometers, and finally accreted onto the Japanese Island when the Western Pacific Plate subducted beneath the Eurasian Plate during the Jurassic.