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FIGURES 10–12 in The first described fossil species of Litargus Erichson (Coleoptera: Mycetophagidae) from Eocene Baltic amber examined with X-ray microtomography, and new records of Crowsonium succinium Abdullah, 1964
FIGURES 10–12. Micro-CT rendering of Litargus (Litargosomus) dantiscensis sp. nov., holotype, No UCPUwB 260, habitus: 10—left lateral view; 11—right lateral view; 12—ventral reconstruction without legs. Scale bar represents 1.0 mm.
FIGURES 6–9 in The first described fossil species of Litargus Erichson (Coleoptera: Mycetophagidae) from Eocene Baltic amber examined with X-ray microtomography, and new records of Crowsonium succinium Abdullah, 1964
FIGURES 6–9. Micro-CT rendering of Litargus (Litargosomus) dantiscensis sp. nov., holotype, No UCPUwB 260, habitus: 6—dorsal view; 7—ventral view; 8—frontal view; 9—caudal view. Scale bar represents 1.0 mm.
FIGURES 13–15 in The first described fossil species of Litargus Erichson (Coleoptera: Mycetophagidae) from Eocene Baltic amber examined with X-ray microtomography, and new records of Crowsonium succinium Abdullah, 1964
FIGURES 13–15. Photomicrograph of Crowsonium succinium Abdullah, collection number AWI-066 [CVIA]: 13—habitus, dorsal view; 14—habitus, ventral view; 15—apical portion of aedeagus, dorsal view. Total body length is 2.5 mm. Not reproduced to the same scale.
FIGURES 4–5 in The first described fossil species of Litargus Erichson (Coleoptera: Mycetophagidae) from Eocene Baltic amber examined with X-ray microtomography, and new records of Crowsonium succinium Abdullah, 1964
FIGURES 4–5. Photomicrographs of Litargus (Litargosomus) dantiscensis sp. nov., holotype, No UCPUwB 260: 4—forebody in dorsal view; 5—details of elytra in ventral view showing punctation and setation. Abbreviations: a2–a11—antennomeres 2–11, respectively; ap—apical maxillary palpomere; cl—clypeus; e—compound eye; fcs—frontoclypeal suture; lab—labrum; bpi—basal pronotal impression. Scale bars represent 0.25 mm.
FIGURES 1–3 in The first described fossil species of Litargus Erichson (Coleoptera: Mycetophagidae) from Eocene Baltic amber examined with X-ray microtomography, and new records of Crowsonium succinium Abdullah, 1964
FIGURES 1–3. Photomicrographs of Litargus (Litargosomus) dantiscensis sp. nov., holotype, No UCPUwB 260: 1—habitus in dorsal view; 2—habitus in ventral view; 3—habitus in left lateral view (3). Scale bars represent 1.0 mm.
Formation binning: a new method for increased temporal resolution in regional studies, applied to the Late Cretaceous dinosaur fossil record of North America
<p>The advent of palaeontological occurrence databases has allowed for detailed reconstruction and analyses of species richness through deep time. While a substantial literature has evolved ensuring that taxa are fairly counted within and between different time periods, how time itself is divided has received less attention. Stage-level or equal-interval age bins have been frequently used for regional and global studies in vertebrate palaeontology. However, when assessing diversity at a regional scale, these resolutions can prove inappropriate with the available data. Herein, we propose a new method of binning geological time for regional studies that intrinsically incorporates the chronostratigraphic heterogeneity of different rock formations to generate unique stratigraphic bins. We use this method to investigate the diversity dynamics of dinosaurs from the Late Cretaceous of the Western Interior of North America prior to the Cretaceous–Palaeogene mass extinction. Increased resolution through formation binning pinpoints the Maastrichtian diversity decline to between 68–66 Ma, coinciding with the retreat of the Western Interior Seaway. Diversity curves are shown to exhibit volatile patterns using different binning methods, supporting claims that heterogeneous biases in this time-frame affect the pre-extinction palaeobiological record. We also show that apparent high endemicity of dinosaurs in the Campanian is a result of non-contemporaneous geological units within large time bins. This study helps to illustrate the utility of high-resolution, regional studies to supplement our understanding of factors governing global diversity in deep time and ultimately how geology is inherently tied to our understanding of past changes in species richness.</p>
Data from: Spatial scaling of beta diversity in the shallow marine fossil record
Beta diversity quantifies the spatial structuring of ecological communities and is a fundamental partition of biodiversity, central to understanding many macroecological phenomena in modern biology and paleobiology. Despite its common application in ecology, studies of beta diversity in the fossil record are limited, particularly at regional spatial scales that are important for understanding macroevolutionary processes. The spatial scaling of beta diversity in the fossil record is poorly understood, but has significant implications due to temporal variation in the spatial distribution of fossil collections and the large spatio-temporal scales typically employed. Here we test the spatial scaling of several common measures of beta diversity using the Cenozoic shallow marine molluscan fossil record of New Zealand, and derive a spatially standardized time series of beta diversity. To measure spatial scaling we use and compare grid cell occupancy based on an equal-area grid and summed minimum spanning tree length, both based on reconstructed paleocoordinates of fossil collections. We find that beta diversity is spatially dependent at local to regional scales, regardless of the metric or spatial scaling utilised, and that spatial standardization significantly changes apparent temporal trends of beta diversity and, therefore, inferences about processes driving diversity change.
Data from: Spatiotemporal variation in completeness of the early cynodont fossil record and its implications for mammalian evolutionary history
<p>Mammals are the only surviving group of Cynodontia, a synapsid clade that first appears in the fossil record in the late Permian, ~260 million years ago. Here, using three metrics that capture skeletal completeness, we quantify the quality of the early cynodont fossil record in time and space to evaluate the impact of sampling and preservational biases on our understanding of the group's evolutionary history. There is no consistent global sampling signal for early cynodonts. Completeness of the cynodont fossil record increases across the Permian/Triassic boundary, peaking in the Early–early Late Triassic. This peak is dominated by specimens from southern Africa and South America, where a highly seasonal climate likely favoured preservation. Completeness is generally lower thereafter, correlated with a shift from a Gondwanan to a predominantly Laurasian fossil record. Phylogenetic and stratigraphic congruence in early cynodonts is high, although their fossil record exhibits less skeletal completeness overall than other tetrapod clades, including the contemporaneous anomodont synapsids. This discrepancy could be due to differences in the diagnosability of their fossils, especially for small-bodied species. Establishing the timing and assembly of derived ('mammalian') anatomical features in Cynodontia is obscured by sampling. Two of the major nodes at which acquisition of mammalian features is concentrated (Cynodontia and Mammaliamorpha) suffer from lengthy intervals of poor sampling prior to becoming abundant parts of tetrapod faunas. Low completeness in these intervals limits our ability to determine when certain 'key' mammalian characteristics evolved, or to identify the selective pressures that might have driven their origins.</p>
FIGURE 2. A–D in First fossil record of a nymph (Ephemeroptera, Teloganellidae) from the Indian subcontinent
FIGURE 2. A–D. Teloganella gurhaensis Agnihotri et al., sp. nov. A. Fossil insect in reflected light. B. Enlarged view of the upper half showing fore-femora, mid-femora and mid-tibia. C. Enlarged head portion with setae (red arrows). D. Enlarged lower half with abdominal segments (red arrows) and terminal filaments (black arrows).
FIGURE 1. A in First fossil record of a nymph (Ephemeroptera, Teloganellidae) from the Indian subcontinent
FIGURE 1. A. Shuttle Radar Topographic Mission (SRTM) digital elevation model (DEM) of Rajasthan (red star showing the location of Gurha lignite mine (fossil locality). B. Litholog of the Gurha lignite mine (after Shukla et al. 2014) showing the location of the fossil insect (red arrow).
FIGURE 1. A, B in The fossil record of the asteroid (Echinodermata) family Chaetasteridae Sladen 1889 and subfamily Hyalothricinae Fisher, 1911
FIGURE 1. A, B, Arthraster dixoni Forbes, 1848. Holotype specimen NHMUK 47000, "Lower Chalk", probably Middle Turonian, Balcombe, Sussex, UK. A, actinal surface, B, enlargement of abactinal surface and base of arms. C–F, Chaetaster longipes (Bruzelius, 1805). C, enlargement of actinal arm. D, enlargement of abactinal disc. E, actinal view of specimen. F, abactinal view of specimen. Recent, Mediterranean.
FIGURE 2. A, B in The fossil record of the asteroid (Echinodermata) family Chaetasteridae Sladen 1889 and subfamily Hyalothricinae Fisher, 1911
FIGURE 2. A, B, Arthraster dixoni Forbes, 1848, small individual, in abactinal (A) and actinal (B) views; Middle Turonian, Dieppe, France; Collection of Nicolas Cottard, Offranville, Normany, France. C–I, Chaetasterina gracilis Hess, 1970. Holotype (NMB Hess A 94), Upper Hauterivian, Neuchâtel, Switzerland, original of Hess (1970: figs 9–14, pl. 3: fig. 5); C, abactinal view; D, actinal view; E–G enlargement of abactinal ossicles; H, I, enlargement of adambulacrals (ad) and inferomarginal (im). J–M, Hyalinothrix sp., Recent, Philippines, AS Gale coll. J, actinal view; K, abactinal view; L, enlargement of ossicles of denuded ambulacral groove; M, enlargement of denuded abactinal surface.
FIGURE 1 in A new fossil record of Lymexylidae (Insecta: Coleoptera) from mid-Cretaceous amber of northern Myanmar
FIGURE 1. Adamas hukawngensis, holotype (CSCLRCAB100180). A. habitus, dorsal view. B. habitus, ventral view. Scale bars: 1.0 mm.
FIGURE 2 in A new fossil record of Lymexylidae (Insecta: Coleoptera) from mid-Cretaceous amber of northern Myanmar
FIGURE 2. Adamas hukawngensis, holotype (CSCLRCAB100180). A. dorsal image of head. B. Drawing of dorsal head. C. Image of antenna. D. Drawing of antenna. E. Image of maxillary palp organ. F. Drawing of maxillary palp organ. G. Image of elytron and scutellum. H. Drawing of elytron and scutellum. Abbreviations: 1º = primary branch; 2 º = secondary branch; I, II, III-XI = scapus, pedicellus, antennal segments III−XI; e = eyes; mp = maxillary palporgan; p IV = palpomere IV; S = scutellum. Scale bars: A–B = 0.1 mm; C–H = 1.0 mm.
FIGURE 3 in A new fossil record of Lymexylidae (Insecta: Coleoptera) from mid-Cretaceous amber of northern Myanmar
FIGURE 3. Adamas hukawngensis, holotype (CSCLRCAB100180). A. Metendosternite. B. Image of metathoracic wing. C. Drawing of metathoracic wing. D. Image of male genitalia, dorsal view. E. Drawing of male genitalia, dorsal view. F. Image of male genitalia, lateral view. G. Drawing of male genitalia, lateral view. Abbreviations: ll = lateral lobes; ml = median lobe. Scale bars: A–C = 1.0 mm; D–G = 0.2 mm.
Data from: Skeletal completeness of the non‐avian theropod dinosaur fossil record
Non‐avian theropods were a highly successful clade of bipedal, predominantly carnivorous, dinosaurs. Their diversity and macroevolutionary patterns have been the subject of many studies. Changes in fossil specimen completeness through time and space can bias our understanding of macroevolution. Here, we quantify the completeness of 455 non‐avian theropod species using the skeletal completeness metric (SCM), which calculates the proportion of a complete skeleton preserved for a specimen. Temporal patterns of theropod skeletal completeness show peaks in the Carnian, Oxfordian–Kimmeridgian and Barremian–Aptian, and lows in the Berriasian and Hauterivian. Lagerstätten primarily drive the peaks in completeness and observed taxonomic diversity in the Oxfordian–Kimmeridgian and the Barremian–Aptian. Theropods have a significantly lower distribution of completeness scores than contemporary sauropodomorph dinosaurs but change in completeness through time for the two groups shows a significant correlation when conservation Lagerstätten are excluded, possibly indicating that both records are primarily driven by geology and sampling availability. Our results reveal relatively weak temporal sampling biases acting on the theropod record but relatively strong spatial and environmental biases. Asia has a significantly more complete record than any other continent, the mid northern latitudes have the highest abundance of finds, and most complete theropod skeletons come from lacustrine and aeolian environments. We suggest that these patterns result from historical research focus, modern climate dynamics, and depositional transportation energy plus association with conservation Lagerstätten, respectively. Furthermore, we find possible ecological biases acting on different theropod subgroups, but body size does not influence theropod completeness on a global scale.
Data from: Appraisal of the fossil record of Homarus (nephropid lobster), with description of a new species from the upper Oligocene of Hungary and remarks on the status of Hoploparia
The fossil record of the clawed lobster genus, Homarus, is appraised. The taxonomic history of Homarus and Hoploparia is summarized, and a list of species recognized for each is provided. A tabulation of all fossil species of the family Nephropidae permits assessment of nephropid species diversity through time. A new species of Homarus, H. hungaricus, is recorded from the upper Oligocene (Chattian) Mány Formation at Mány, northern Hungary. The species is known by a single specimen consisting of a partial cephalothorax, a pleon minus telson, and partial chelipeds. Homarus is now known by two extant species (H. americanus and H. gammarus) and six fossil taxa, one of Early Cretaceous (Albian; H. benedeni) and five of Cenozoic age (H. hungaricus n. sp., H. klebsi, H. lehmanni, H. morrisi, and H. percyi). The new fossil Homarus differs from modern congeners in aspects of carapace and pleon ornamentation and, especially, cutter claw shape. This is the fourth Oligocene occurrence of a nephropid species; all are Homarus and all are from Western Europe. Homarus makes its appearance in the fossil record in the Early Cretaceous (Albian) and then is not known again until the Paleogene, despite the fact that nephropid lobsters in general are well known from the Late Cretaceous. Nephropid lobsters are better known from the Cretaceous than from the Cenozoic. Both raw species numbers and numbers corrected (normalized) for epicontinental sea coverage show that shelf-dwelling nephropid lobsters were most diverse during the Late Cretaceous.
Data from: The fossil record and macroevolutionary history of the beetles
Coleoptera (beetles) is the most species-rich metazoan order, with approximately 380 000 species. To understand how they came to be such a diverse group, we compile a database of global fossil beetle occurrences to study their macroevolutionary history. Our database includes 5553 beetle occurrences from 221 fossil localities. Amber and lacustrine deposits preserve most of the beetle diversity and abundance. All four extant suborders are found in the fossil record, with 69% of all beetle families and 63% of extant beetle families preserved. Considerable focus has been placed on beetle diversification overall, however, for much of their evolutionary history it is the clade Polyphaga that is most responsible for their taxonomic richness. Polyphaga had an increase in diversification rate in the Early Cretaceous, but instead of being due to the radiation of the angiosperms, this was probably due to the first occurrences of beetle-bearing amber deposits in the record. Perhaps, most significant is that polyphagan beetles had a family-level extinction rate of zero for most of their evolutionary history, including across the Cretaceous–Palaeogene boundary. Therefore, focusing on the factors that have inhibited beetle extinction, as opposed to solely studying mechanisms that may promote speciation, should be examined as important determinants of their great diversity today.
Data from: Methods for the quantitative comparison of molecular estimates of clade age and the fossil record
Approaches quantifying relative congruence, or incongruence, of molecular divergence estimates and the fossil record have been limited. Previously proposed methods are largely node specific, assessing incongruence at particular nodes for which both fossil data and molecular divergence estimates are available. These existing metrics, and other methods that quantify incongruence across topologies including entirely extinct clades, have so far not taken into account uncertainty surrounding both the divergence estimates and the ages of fossils. They have also treated molecular divergence estimates younger than previously assessed fossil minimum estimates of clade age as if they were the same as cases in which they were older. However, these cases are not the same. Recovered divergence dates younger than compared oldest known occurrences require prior hypotheses regarding the phylogenetic position of the compared fossil record and standard assumptions about the relative timing of morphological and molecular change to be incorrect. Older molecular dates, by contrast, are consistent with an incomplete fossil record and do not require prior assessments of the fossil record to be unreliable in some way. Here, we compare previous approaches and introduce two new descriptive metrics. Both metrics explicitly incorporate information on uncertainty by utilizing the 95% confidence intervals on estimated divergence dates and data on stratigraphic uncertainty concerning the age of the compared fossils. Metric scores are maximized when these ranges are overlapping. MDI (minimum divergence incongruence) discriminates between situations where molecular estimates are younger or older than known fossils reporting both absolute fit values and a number score for incompatible nodes. DIG range (divergence implied gap range) allows quantification of the minimum increase in implied missing fossil record induced by enforcing a given set of molecular-based estimates. These metrics are used together to describe the relationship between time trees and a set of fossil data, which we recommend be phylogenetically vetted and referred on the basis of apomorphy. Differences from previously proposed metrics and the utility of MDI and DIG range are illustrated in three empirical case studies from angiosperms, ostracods, and birds. These case studies also illustrate the ways in which MDI and DIG range may be used to assess time trees resultant from analyses varying in calibration regime, divergence dating approach or molecular sequence data analyzed.
Data from: Detecting diversification rates in relation to preservation and tectonic history from simulated fossil records
For mammals today, mountains are diverse ecosystems globally, yet the strong relationship between species richness and topographic complexity is not a persistent feature of the fossil record. Based on fossil-occurrence data, diversity and diversification rates in the intermontane western North America varied through time, increasing significantly during an interval of global warming and regional intensification of tectonic activity from 18 to 14 Ma. However, our ability to infer origination and extinction rates reliably from the fossil record is affected by variation in preservation history. To investigate the influence of preservation on estimates of diversification rates, I simulated fossil records under four alternative diversification hypotheses and six preservation scenarios. Diversification hypotheses included tectonically-controlled speciation pulses, while preservation scenarios were based on common trends (e.g., increasing rock record towards the present) or derived from fossil occurrences and the continental rock record. For each scenario, I estimated origination, extinction, and diversification rates using three standard methods—per-capita, three-timer, and capture-mark-recapture metrics—and evaluated the ability of the simulated fossil records to accurately recover the underlying diversification dynamics. Despite variable and low preservation probabilities, simulated fossil records retained the signal of true rates in several of the scenarios. The three metrics did not exhibit similar behavior under each preservation scenario: while three-timer and capture-mark-recapture metrics produced more accurate rate estimates, per-capita rates tended to better reproduce true shifts in origination rates. All metrics suffered from spurious peaks in origination and extinction rates when highly volatile preservation impacted the simulated record. Results from these simulations indicate that elevated diversification rates in relation to tectonic activity during the middle Miocene are likely to be evident in the fossil record, even if preservation in the North American fossil record was variable. Input from the past is necessary to evaluate the ultimate mechanisms underlying speciation and extinction dynamics.
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