Find research datasets worth reusing

opencc-zeroJul 2020View details →

Data from: Ten more years of discovery: revisiting the quality of the sauropodomorph dinosaur fossil record

Spatiotemporal changes in fossil specimen completeness can bias our understanding of a group's evolutionary history. The quality of the sauropodomorph fossil record was assessed a decade ago, but the number of valid species has since increased by 60%, and 17% of the taxa from that study have since undergone taxonomic revision. Here, we assess how 10 years of additional research has changed our outlook on the group's fossil record. We quantified the completeness of all 307 sauropodomorph species currently considered valid, using the skeletal completeness metric, which calculates the proportion of a complete skeleton preserved for each taxon. Taxonomic and stratigraphic age revisions, rather than new species, are the drivers of the most significant differences between the current results and those of the previous assessment. No statistical differences are found when we use our new dataset to generate temporal completeness curves based on only the taxa known in 2009 or 1999. We now observe a severe drop in mean completeness values across the Jurassic/Cretaceous boundary that never recover to pre-Cretaceous levels. Explaining this pattern is difficult, as we find no convincing evidence it is related to environmental preferences or body size changes. Instead, it might result from: (1) reduction of terrestrial fossil preservation space due to sea level rise; (2) ecological specificities and relatively high diagnosability of Cretaceous species; and/or (3) increased sampling of newly explored sites with many previously unknown taxa. Revisiting patterns in this manner allows us to test the longevity of conclusions made in previous quantitative studies.

opencc-zeroMar 2024View details →

Data from: A winged relative of ice crawlers in amber bridges the cryptic extant Xenonomia and a rich fossil record

Until the advent of phylogenomics, the atypical morphology of extant representatives of the insect orders Grylloblattodea (ice crawlers) and Mantophasmatodea (gladiators) had confounding effects on efforts to resolve their placement within Polyneoptera. This recent research has unequivocally shown that these species‐poor groups are closely related and form the clade Xenonomia. Nonetheless, divergence dates of these groups remain poorly constrained, and their evolutionary history debated, as the few well‐identified fossils, characterized by a suite of morphological features similar to that of extant forms, are comparatively young. Notably, the extant forms of both groups are wingless, whereas most of the pre‐Cretaceous insect fossil record is composed of winged insects, which represents a major shortcoming of the taxonomy. Here, we present new specimens embedded in Early Cretaceous amber from Myanmar and belonging to the recently described species Aristovia daniili. The abundant material and pristine preservation allowed a detailed documentation of the morphology of the species, including critical head features. Combined with a morphological data set encompassing all Polyneoptera, these new data unequivocally demonstrate that A. daniili is a winged stem Grylloblattodea. This discovery demonstrates that winglessness was acquired independently in Grylloblattodea and Mantophasmatodea. Concurrently, wing apomorphic traits shared by the new fossil and earlier fossils demonstrate that a large subset of the former "Protorthoptera" assemblage, representing a third of all known insect species in some Permian localities, are genuine representatives of Xenonomia. Data from the fossil record depict a distinctive evolutionary trajectory, with the group being both highly diverse and abundant during the Permian but experiencing a severe decline from the Triassic onwards.

opencc-zeroMar 2024View details →

A critique of Thompson and Ramírez-Barahona (2023) or: how I learned to stop worrying and love the fossil record

A recent study published in Biology Letters by Thompson and Ramírez-Barahona (2023) argued that, according to analyses of diversification on two massive molecular phylogenies comprising thousands of species, there is no evidence that angiosperms (i.e., flowering plants) were affected by the Cretaceous-Paleogene mass extinction. Here I critique these conclusions from both methodological and philosophical perspectives. I demonstrate that the methods used in their study possess statistical limitations that strongly reduce the power to detect a true mass extinction event using data similar to those analyzed by Thompson and Ramírez-Barahona (2023). Additionally, I use their study as a springboard to examine the relationship between phylogenetic and fossil evidence in diversification studies.

opencc-zeroDec 2021View details →

Chondrichthyan specimen data from the Florida fossil record

As of September 2019, the Florida Museum of Natural History (FLMNH) had a curated collection of 117,449 chondrichthyan specimens from Florida, spanning the Eocene through the Pleistocene. Herein, I evaluated the completeness of the chondrichthyan fossil record from Florida based on the FLMNH collection, while analyzing patterns in taxonomic and ecomorphological diversity. At least 70 chondrichthyan taxa were recognized, representing 10 orders, 26 families, and 42 genera; of which, 20 taxa represent first occurrences from Florida. A sample of 107,698 specimens was organized into 12 time bins to analyze taxonomic and ecomorphological diversity, with an expectation that diversity patterns would correspond with global climate events (e.g., the Eocene-Oligocene Transition and the Middle Miocene Climatic Optimum). However, diversity patterns were obscured by pervasive sampling bias, attributable to variable collection methods, research prioritizations, and regional lithologic controls. Sampling is particularly poor for smaller specimens and older geologic units (e.g., the Paleogene). Despite incomplete sampling of the Florida chondrichthyan fossil record, there was an apparent turnover along the Atlantic and Gulf coastal plains from a lamniform to carcharhiniform dominated chondrichthyan fauna that occurred during the Eocene. This turnover corresponded with the extinction of many lamniform taxa with grasping-dominated dentition types (e.g., Brachycarcharias, Jaekelotodus, and Macrorhizodus). Selachian taxa that survived the late Eocene extinctions were predominantly represented by cutting-dominant dentition types. Since cutting aids in the dismemberment of prey, this may reflect a macroevolutionary trend towards active predation and scavenging on larger prey, such as marine mammals, teleost fish, and other sharks.

opencc-zeroMay 2022View details →

Data from: Phylogenomic analyses of echinoid diversification prompt a re-evaluation of their fossil record

Echinoids are key components of modern marine ecosystems. Despite a remarkable fossil record, the emergence of their crown group is documented by few specimens of unclear affinities, rendering their early history uncertain. The origin of sand dollars, one of its most distinctive clades, is also unclear due to an unstable phylogenetic context. We employ eighteen novel genomes and transcriptomes to build a phylogenomic dataset with a near-complete sampling of major lineages. With it, we revise the phylogeny and divergence times of echinoids, and place their history within the broader context of echinoderm evolution. We also introduce the concept of a chronospace—a multidimensional representation of node ages—and use it to explore methodological decisions involved in time calibrating phylogenies. We find the choice of clock model to have the strongest impact on divergence times, while the use of site-heterogeneous models and alternative node prior distributions showing minimal effects. The choice of loci has an intermediate impact, affecting mostly deep Paleozoic nodes, for which clock-like genes recover dates more congruent with fossil evidence. Our results reveal that crown group echinoids originated in the Permian and diversified rapidly in the Triassic, despite the relative lack of fossil evidence for this early diversification. We also clarify the relationships between sand dollars and their close relatives and confidently date their origins to the Cretaceous, implying ghost ranges spanning approximately 50 million years, a remarkable discrepancy with their rich fossil record.

opencc-zeroJun 2022View details →

Data from: Skeletal and soft tissue completeness of the acanthodian fossil record

Acanthodians are a poorly understood paraphyletic grade of extinct Palaeozoic fishes. They play an increasingly prominent role in our understanding of vertebrate evolution as part of the chondrichthyan stem-group even though their evolutionary history is scarce. The limited preservation of their mostly cartilaginous skeleton largely results in a bias towards isolated remains such as fin spines and scales. Here, we quantify the quality of the acanthodian fossil record by using a variation of the Skeletal Completeness Metric (SCM), an approach that calculates how complete the skeletons of individuals are compared to their theoretical complete skeleton. A novel Soft Tissue Completeness Metric (STCM) is introduced to estimate the percentage of soft body tissue preserved as an alternate measurement of completeness. Completeness scores for >1600 specimens comprising >300 taxa obtained from museum collection visits and literature surveys were assembled into a database. Acanthodian completeness peaks in the Lochkovian, Givetian, Bashkirian-Moscovian, and the Asselian, with lowest scores in the Llandovery. There is no correlation between acanthodian taxonomic richness and completeness. Acanthodians show a significantly lower completeness distribution than many tetrapod groups, but a similarly low distribution to bats. Skeletons deposited in freshwater are significantly more complete than in marine environments where sea level significantly negatively correlates with observed completeness. Our assessment of completeness reveals only weak spatial biases influencing the acanthodian fossil record while environmental biases are much higher. Variation in completeness will have an impact on the utility of characters for assessing the phylogenetic relationships and inclusion of the various acanthodian groups.

opencc-zeroApr 2024View details →

Data from: Palaeoscolecids from the Ludlow Series of Leintwardine, Herefordshire (UK) – the latest occurrence of palaeoscolecids in the fossil record.

The documentation of cuticular micro-ornament is vital for the taxonomic assignment of palaeoscolecids – vermiform lower Palaeozoic ecdysozoans interpreted as stem-group priapulans or early diverging panarthropods. This is due to the absence of the character-rich proboscis and tail hooks in palaeoscolecid material not from Burgess Shale-type Konservat-Lagerstätten. Here, the cuticular micro-ornamentation of palaeoscolecids from the upper Silurian (Ludlow) fauna of Leintwardine (Herefordshire, England), is described using scanning electron microscopy (SEM) and Reflectance Transformation Imaging (RTI). This material is taxonomically unstable as it was included in an effective wastebasket genus (Protoscolex) long before these imaging techniques were developed. This reveals the Leintwardine material is most closely comparable to a palaeoscolecid from the Darriwilian (Middle Ordovician) of the Builth-Llandrindod inlier, Powys, Wales and is transferred accordingly to Radnorscolex Botting et al. as Radnorscolex latus Bather. The Leintwardine fauna represents the uppermost stratigraphic occurrence of palaeoscolecids, constrained to the Saetograptus leintwardinensis Zone (lower Ludfordian), and the comparatively sparse Silurian palaeoscolecid record is subsequently discussed. It is hypothesised palaeoscolecids may have become extinct during the mid-Ludfordian Lau Event, the onset of which is recorded in the biozone immediately above the Leintwardine fauna (Bohemograptus Zone). Finally, the British palaeoscolecid fauna is summarised, including a new record from the Dapingian (Middle Ordovician) of Carmarthenshire, South Wales. --

opencc-by-4.0Dec 2023View details →

Fig. 4 in The early fossil record of Caturoidea (Halecomorphi: Amiiformes): biogeographic implications

Fig. 4 Stratigraphic distribution of the nannotaxa identified in MPCA 632. Plots von Nannotax 3

opencc-by-4.0Jul 2024View details →

Figure 1 in Diplopoda in the world fossil record

Figure 1. Fossil record of millipedes around the world. Schematic map showing geological sites.

opencc-by-4.0Oct 2014View details →

Text-fig. 1. Ground plan of Za Hájovnou Cave (according Tomica, supplemented by Musil, 2005). in Panthera Fossilis (Reichenau, 1906) (Felidae, Carnivora) From Za Hájovnou Cave (Moravia, The Czech Republic): A Fossil Record From 1987-2007

Text-fig. 1. Ground plan of Za Hájovnou Cave (according Tomica, supplemented by Musil, 2005).

opencc-by-4.0Sep 2015View details →

FIGURE 1 in New plant fossil records and paleoclimate analyses of the late Pliocene Citronelle Formation flora, U.S. Gulf Coast

FIGURE 1. Index map of plant fossil localities of the Citronelle Formation.

opencc-by-4.0Aug 2015View details →

FIGURE 7. Isolated chambers. 1 in Neoichnology of the eastern spadefoot toad, Scaphiopus holbrookii (Anura: Scaphiopodidae): criteria for recognizing anuran burrows in the fossil record

FIGURE 7. Isolated chambers. 1, Side view (SH20). 2, Frontal view (SH20). 3, Frontal view (SH67).

opencc-zeroSep 2019View details →

Data from: The first pre-Quaternary fossil record of the clade Mabuyidae with a comment on the enclosure of the Meckelian canal in skinks

We here describe the first Neogene record of the squamate clade Mabuyidae. Although this clade has a cosmopolitan distribution today, no pre-Quarternary fossil record of these reptiles has so far been documented. The material comes from the locality Solnechnodolsk (Russia) and is dated to the late Miocene (MN 13). Although it comprises only jaw elements, it constitutes the first evidence of the occurrence of fossil skinks around the area of the Black Sea. The material is identical to Heremites vittatus, showing the existence of this lineage as early as the late Miocene. Thus, it may be used as a potential calibration point for further studies. The comparative anatomy of the structures of lower jaw in selected scincomorph taxa with a special reference to Mabuya group is presented. The closure of the Meckelian canal is the condition at the basal node of the clade Sphenomorphidae + Eugongylidae + Egerniidae + Mabuyidea, whereas the closed canal in Acontias (Acontidae) evolved independently. However, Sphenomorphidae (Asymblepharus and Scincella) + Eugongylidae (Ablepharus) retain a large anterior opening of the Meckelian canal, whereas only a small opening characterizes the basal node of Egerniidae and Mabuyidae, except for H. vittatus and H. septemtaeniatus. The closure of the Meckelian canal in these two taxa is less well developed in comparison with other mabuyid skinks. Thus, a heterochronic pedomorphic process might have played a role in the evolution of these skinks. The Meckelian canal condition supports the monophyly of Heremites.

Fig. 5 in The Phylogenetic Resolving Power of Discrete Dental Morphology Among Extant Hedgehogs and the Implications for Their Fossil Record

Fig. 5. Atelerix albiventris (AMNH 165804) upper and lower jaw.

Fig. 7 in The Phylogenetic Resolving Power of Discrete Dental Morphology Among Extant Hedgehogs and the Implications for Their Fossil Record

Fig. 7. Hemiechinus auritus (AMNH 85309) upper and lower jaw.

Fig. 4 in The Phylogenetic Resolving Power of Discrete Dental Morphology Among Extant Hedgehogs and the Implications for Their Fossil Record

Fig. 4. Hylomys sinenesis (AMNH 10106) upper and lower jaw.

Fig. 6 in The Phylogenetic Resolving Power of Discrete Dental Morphology Among Extant Hedgehogs and the Implications for Their Fossil Record

Fig. 6. Erinaceus europeaus (AMNH 70611) upper and lower jaw.

Fig. 3 in The Phylogenetic Resolving Power of Discrete Dental Morphology Among Extant Hedgehogs and the Implications for Their Fossil Record

Fig. 3. Echinosorex gymnura (AMNH 115519) upper and lower jaw.