Kenneth De Baets

@djbirddanerd

Paleobiologist @ibe-warszawa.bsky.social into cephalopods, parasites, funny tees and movies; Paleontology/Evolution Section Editor @PeerJLife ; previously @palaeofau. Avatar after Jacek Yerka also on @djbirddanerd@ecoevo.social

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Kenneth De Baets@djbirddanerd· 1d

That changed ~90 million years ago, when 3 major parasitic 🪱 lineages (Ascarididae, Onchocercidae, Strongyloidea) exploded in diversity—right as #mammals and #birds radiated. A stunning example of coevolution nicely illustrated by @franzanth.bsky.social 🐦‍⬛🦦 #Fossils #Evolution #Parasites #Genomics

Evolution of nematode parasitism Fan-shaped trees display the change in likelihood (upper; lik.P: 0 = free-living (FL), 1 = parasitic (PS)) and net diversification rate (lower; net.div) over time. Right: average rates (bars: s.d.) of nodes in each 10-Myr bin and tips from HiSSE models (excluding tardigrade nodes (TG)). Yellow strips: estimate ranges at nodes from all non-redundant HiSSE models; the rightmost grey strip shows that at tips. Red and blue colour indicates the results from model average (‘Avg’) and the best model (‘Bst’), respectively. Embedded histograms summarize the rate distribution for nodes pre- or post-90 Ma. The 2 × 2 or 4 × 2 tables show the mean net diversification rate (minus effect of parental node) across marginal conditions; the letters in each cell denote statistical significance (α = 0.05) in ANCOVA and post hoc comparisons. Geological eras and periods follow Fig. 2. Pst, present. https://dx.doi.org/10.1038/s41559-026-03128-9

Reconstruction showing a nematode surrounded by a bird (crow) and a mammal (otter) underlining the relationship between diversification in parasitic nematodes and that of birds and mammals. Reconstruction by Franz @franzanth.bsky.social

Kenneth De Baets@djbirddanerd· 1d

The first shifts to parasitism happened much later—Late #Devonian to end #Carboniferous (~380–300 million years ago). But here’s the twist: for most of their history, #parasitic #nematodes didn’t diversify faster than #free-living ones. 🧬

Time-calibrated trees and patterns of parasitism and living ranges in Nematoda A condensed stack of the average time trees for the nine DBSCAN clusters (cLG-PMSF topology, benchmarking calibrations) is presented alongside the sensitivity analyses using alternative calibrations (cLG-PMSFw, cLG-PMSFx and cLG-PMSFy) or topologies (C60-PMSF, LG and TRAD). The average tree of cluster 2 is zoomed in to view diversification. The rightmost column of bands denotes the lifestyle trait (white: free-living; black: parasitic; grey: ambiguous), detailed in Supplementary Table 16. Silhouettes represent the most common host types of the relevant nematodes. Geological eras/periods: Cz, Cenozoic; K, Cretaceous; J, Jurassic; T, Triassic; P, Permian; Cn, Carboniferous; D, Devonian; S, Silurian; O, Ordovician; Cm, Cambrian; PreCm, Precambrian. Icons from PhyloPic under a Creative Commons license: human (PDM 1.0); Blattoidea (CC BY 4.0); all others available under a CC0 1.0 license. https://dx.doi.org/10.1038/s41559-026-03128-9

Kenneth De Baets@djbirddanerd· 1d

New research integrates #genomic data (184 species, 156 nematodes) + #fossil record to map their evolutionary timeline. The last common ancestor of #nematodes? Likely a free-living organism from the late #Cambrian to Middle #Ordovician (~480–460 million years ago). 🌊

Clustering and parameter analysis of time-calibrated phylogenetic trees in MCMCTree. Panels (a) and (b) show redundancy analysis (RDA) of parameter effects on node age estimates across 432 time trees (a: all trees, including unconverged; b: 132 converged estimates only). Venn diagrams illustrate variance partitioning among the four key explanatory variables. Panel (c) presents a SHAP summary of feature contributions to MCMC chain convergence, with Nightingale’s diagram embedding feature importance (gain). Panels (d–f) display converged time estimates grouped into ≤12 clusters via DBSCAN, visualized using t-SNE (d), a PRD matrix (e), and AutoEncoder-compressed medians with 95% HPD ranges (f). Panel (g) compares age estimates and 95% HPD intervals of key clades from centroid and average time trees, including sensitivity analyses for alternative calibrations/topologies. Red dots indicate values from unconverged chains. https://dx.doi.org/10.1038/s41559-026-03128-9

Kenneth De Baets@djbirddanerd· 2d

Boundaries of #Geoheritage in the Tafilalt and Maïder Regions, an Eldorado for #Palaeozoic #Cephalopods: rdcu.be/fAk15 #Morocco doi.org/10.1007/s123...

Cephalopod (ca. 10 to 30 cm long) fossils from the Tafilalt: mass occurrence of Temperoceras ludense, a large late Silurian orthoceratid from Ouidane Chebbi

Cephalopod fossils from the Tafilalt: late Eifelian ammonoids from the Taouz region including Cabrieroceras, Subanarcestes and Agoniatites (reconstruction of the latter inserted, palaeoart by Christian Klug)

Kenneth De Baets@djbirddanerd· 8d

New to #Coprolites or #PoopScience but almost 20 years of #International #Research left their mark on multiple subjects including #biology #paleontology #macroevolution #paleoecology #parasitology #biogeography #geoscience #stratigraphy #physiology #taphonomy straddling the #Phanerozoic and #World

Word cloud shaped in a particular outline showing the most popular words used in research of Kenneth De Baets created using https://scholargoggler.com/

Kenneth De Baets@djbirddanerd· 16d

Drought and trajectory to forest dieback in CH: since weeks it is too dry in many places - various villages in Fricktal (www.fricktal.info/news/gemeind...) have measures to ration drinking water. The question remains if the trees will survive - brown leaves that early in August is not a good sign.

Picture from our balcony in Wittnau where rations. Note the brown leaves in almost all tree crowns in the forest as well as the try fields. It likely will also not be a good harvest for farmers. Drinking water rations are clearly needed but on the long-term a plan for the entire canton or country including cooperation between villages and general considerations for (drinking) water sustainability and measures to restrict draught.

Kenneth De Baets@djbirddanerd· Jun 26

Automated recognition of Meso-Cenozoic #foraminifera from Senegalese sedimentary deposits using #convolutional #neural #networks => the study considers diagenetic alteration and biostratigraphy: peerj.com/articles/21437 #Ecology #MarineBiology #Paleontology #MachineLearning @peerj.bsky.social

Semi-automated workflow diagram for the acquisition and classification of foraminifera images. The 10-step process depicted includes: (1) acquisition of images covering all species of planktonic and benthic foraminifera and fragments; (2) compilation of a database containing 52,280 images; (3) random selection of images for high-level labeling into two classes (fragments and microfossils); (4) coarse labeling of selected images; (5) training of a Convolutional Neural Network (CNN) using coarse-labeled images; (6) application of the trained CNN to label and separate fragments from the full dataset; (7) random selection of images for fine labeling at genus and species level using Particule-Trieur software; (8) training of a CNN with fine-labeled images; (9) application of the trained CNN to label remaining microfossil images; and (10) generation of a confusion matrix to evaluate CNN efficacy in recognizing different foraminifera species and genera. https://doi.org/10.7717/peerj.21437/fig-3

Examples of images depicting planktonic and benthic foraminifera identified in the CM10 samples, which may be confused based on morphological similarities particularly in case of diagenetic alterations: (A) Muricohedbergella sp. (3,000 m, late Cenomanian-Turonian) with (B) Planohedbergella sp. (3,000 m, late Cenomanian-early Campanian); (C) Archaeoglobigerina spp. (1,500 m, late Cenomanian-Turonian) with (D) Subbotina spp. (1,100 m, late Maastrichtian-Paleocene); (E) Acarinina spp. (1,100 m, late Maastrichtian-Paleocene) with (F) Morozovella spp. (1,200 m, late Maastrichtian-Paleocene); (G) Heterohelix sp. (2,200 m, late Cenomanian-Paleocene) with (H) Planohedbergella sp. (3,000 m, late Cenomanian-early Campanian); (I) Gavelinella sp. (2,000 m, Maastrichtian) with (J) Lenticulina spp. (900 m, Paleocene); (K) Ammobaculites sp. (2,500 m, Turonian-Campanian) with (L) Budashevaella sp. (2,100 m, late Campanian-late Paleocene). https://doi.org/10.7717/peerj.21437/fig-8

Biostratigraphic ranges chart of major foraminifera species identified in Meso-Cenozoic sediment samples from the CM10 core. The figure compares depth distributions of foraminifera species identified by a Convolutional Neural Network (CNN) against expert-based biostratigraphic classifications. Dark purple circles mark CNN identifications, with circle sizes proportional to the normalized abundance of each taxon at each depth. Pink rectangles indicate the stratigraphic range of key species as determined by human experts using classical biostratigraphic frameworks (Ly & Kuhnt, 1994). CNN results span the full dataset, while expert ranges provide a visual benchmark for comparison. The plot has depth on the y-axis (in m) and taxa along the x-axis. 10.7717/peerj.21437/fig-7

Kenneth De Baets@djbirddanerd· Jun 25

It may also indicate a high prevalence of tapeworms in Permian aquatic ecosystems, but #preservation factors (e.g.., cyanobacteria, laminae) and final #host #ecology (e.g., shark based on morphology of coprolite) likely also contributed to the exceptional richness of these discoveries.

Coprolite morphology and close-up of non-spherical inclusions in PV 634-P thin section, shark coprolite from Coproland, Brazil, Rio do Rasto Formation, Guadalupian (middle Permian). A: Flattened heteropolar coprolite with interpreted biofilm laminae. B: Whorls exhibiting mucosal folds. C: Preserved fish scales showing internal structures (C1) and 3-layered structure (C2). D: Filaments interpreted as filamentous cyanobacteria (D1), showing short, straight, non-branched structures with lighter sections consistent with cell-boundaries (D2, cyanobacteria indicated by arrows). More information in Dentzien-Dias et al. 2026, Acta Palaeontologica Polonica 71 (2), 2026: 323-335 doi:10.4202/app.01294.2025

Kenneth De Baets@djbirddanerd· Jun 25

The abundance and diversity of these parasite eggs in Coproland spiral shark coprolites corroborate the presence of complex life cycles and suggest diverse transmission strategies.

Close-up of spherical inclusions type A1 in PV 634-P thin section. Shark coprolite from Coproland, Brazil, Rio do Rasto Formation, Guadalupian (middle Permian). Panel A: Cluster of subspherical bodies interpreted as tapeworm eggs within a cocoon. Panel B: Single spherical body showing three pairs of hook-like structures and a distinct outer shell surrounded by others. Includes petrographic microscope photos and interpretative drawings. More information in Dentzien-Dias et al. 2026,
Acta Palaeontologica Polonica 71 (2), 2026: 323-335 doi:10.4202/app.01294.2025

Kenneth De Baets@djbirddanerd· Jun 25

The discovered #eggs within the packet (A1), exhibit structures like #oncospheres with paired #hooks, morphologically comparable to extant taxa (e.g., Echinobothrium, Dipylidium, and Kapsulotaenia). Isolated eggs with thicker walls (A2) are more reminiscent of Taeniidae in size and structure.

Close-up of spherical inclusions type A2 in PV 634-P thin section, shark coprolite from Coproland, Brazil, Rio do Rasto Formation, Guadalupian (middle Permian). Shows isolated spherical bodies interpreted as tapeworm eggs. Includes Keyence HX-7000 photo and interpretative drawing. More information in Dentzien-Dias et al. 2026, Acta Palaeontologica Polonica 71 (2), 2026: 323-335 doi:10.4202/app.01294.2025

Kenneth De Baets@djbirddanerd· Jun 25

Our study reports two new types of eggs attributable to tapeworms in a Permian vertebrate coprolite from the Coproland outcrop, Brazil, expanding previous records and providing insights into helminth diversity during the late Palaeozoic. dx.doi.org/10.4202/app.01294.2025

Hypothetical reconstruction of tapeworm parasite life cycles from shark coprolites, Coproland, Brazil, Rio Do Rasto Formation, Guadalupian (middle Permian). Filled arrows show direct evidence, stippled arrows indicate less certain connections, and possibilities from circumstantial inference are discussed in text. Panels: A) Conchostracan as possible first intermediate host; B) Bony fish as second or first intermediate host; C) Tapeworm egg development in host muscle tissue; D) Shark with spiral intestine as definitive host; E) Defecation; F) Tapeworm eggs in faeces preserved as mineralized coprolites. More information in Dentzien-Dias et al. 2026, Acta Palaeontologica Polonica 71 (2), 2026: 323-335 doi:10.4202/app.01294.2025

Kenneth De Baets@djbirddanerd· Jun 25

#Multiple records of #tapeworm eggs from #Permian #coprolites and their palaeoparasitological significance: dx.doi.org/10.4202/app.01294.2025 #Platyhelminthes, #Cestoda, #bromalite, #palaeoparasitology, Rio do Rasto Formation, #Permian, #Paraná Basin #Paleobiology #Fossils

Kenneth De Baets@djbirddanerd· Jun 25

#Three-dimensionally preserved #appendages of the early #Cambrian #trilobite Yunnanocephalus yunnanensis @peerj.bsky.social peerj.com/articles/21095 #Biodiversity #Evolution #Paleobiology #Paleontology #Taxonomy #Fossils

3D reconstruction of the biramous appendage of Yunnanocephalus yunnanensis (Mansuy, 1912) with six labeled views: dorsal, ventral, anterior, posterior, lateral distal, and lateral proximal. The protopodite and endopodite are based on direct scan observations, while the exopodite is reconstructed by inference. Labeled structures include endites, endopodite, exopodite (proximal and distal lobes), gnathobasic spines, lamellae, protopodite, setae, and terminal claw. Not to scale. More information: https://doi.org/10.7717/peerj.21095/fig-5

X-ray microcomputed tomography model of Yunnanocephalus yunnanensis (Mansuy, 1912), specimen YKLP 17210, showing six views: dorsal, lateral, ventral-lateral, ventral, antennae detail, and first thoracic appendages in ventral view. Labeled structures include antennae, articles, cephalon, endopodite, exopodite, left and right cephalic and thoracic appendages (lC1–lC4, lT1–lT14, rT1–rT14), and thorax. Scale bars: 2 mm (A–D), 0.5 mm (E), 1 mm (F). More information: https://doi.org/10.7717/peerj.21095/fig-1

X-ray microcomputed tomography model of Yunnanocephalus yunnanensis (Mansuy, 1912), specimen YKLP 17211, showing six views: dorsal, lateral, ventral-lateral, ventral, ventral view of the cephalic area, and detail of the first thoracic appendages in ventral view. Labeled structures include antennae, endites, endopodite, exopodite, gnathobasic spines, putative hypostome and labrum, lamellae, left and right cephalic and thoracic appendages (lC1–lC4, rC2–rC4, lT1–lT16, rT1–rT16), and terminal claw. Scale bars: 3 mm (A–D), 2 mm (E–F). More information: https://doi.org/10.7717/peerj.21095/fig-3

Kenneth De Baets@djbirddanerd· Jun 22

🌀 #Size / #ontogeny emerges as the primary driver of conch shape variation, while ribbing patterns follow #phylogenetic controls—refining systematic criteria for paleobiological studies.

Six fossil ammonite specimens representing the main morphologies of the Echioceratidae family, displayed side-by-side. The shells are coiled (serpenticone) with varying degrees of whorl depression and ribbing strength. From left to right: 1) Gagaticeras gagateum, 2) Palaeoechioceras spirale, 3) Plesechioceras delicatum, 4) Echioceras raricostatoides, 5) Leptechioceras macdonnelli, and 6) Paltechioceras elicitum. Each specimen represents the type material (holotype, neotype, or lectotype) for its respective genus. The images show natural variations in fossil preservation; all figures sourced from Howarth (2013) and are not drawn to scale relative to one another.

Kenneth De Baets@djbirddanerd· Jun 22

Key findings: ✓ #Taphonomic alteration doesn't significantly distort conch shape in evolute forms ✓ Strong #allometric signal: larger specimens are consistently more evolute ✓ #Ornamentation & conch shape covary predictably (stronger ribs → depressed whorls, but independent of involution)

A U-H1 biplot scatter diagram illustrating the relationship between umbilical width (U) and last whorl height (H) ratios for Paltechioceras ammonite specimens, colored by shell diameter to show size variation. The data points transition from dark blue to red based on size: dark blue represents the smallest specimen (11.2 mm), while red represents the largest specimen (197.0 mm). This color gradient visualizes how morphological proportions change across the range of ontogenetic growth within the genus.

Four-panel scientific figure comparing Paltechioceras ammonite specimens across different preservation states using scatter plots and box plots. Orange points represent P. tardecrescens specimens from level OU218 (LB group); blue points represent Paltechioceras genus specimens from bibliographical references (OR group).

Panel A: Scatter plot (x-y plot) showing umbilical width (u) plotted against shell diameter (d).
Panel B: Box plot displaying U values (umbilical ratio calculated as u/d).
Panel C: Scatter plot (x-y plot) showing last whorl height (wh) plotted against shell diameter (d).
Panel D: Box plot displaying H values (last whorl ratio calculated as wh/d).
Together, these projections compare morphological measurements between locally collected and literature-sourced specimens, allowing evaluation of preservation state effects on conch dimensions.

A W-A biplot scatter diagram displaying the relationship between whorl width (W) and whorl height (A) for Echioceratidae ammonite specimens, grouped by rib strength. The data includes six genera: Palaeoechioceras, Gagaticeras, Plesechioceras, Echioceras, Paltechioceras, and Leptechioceras. Specimens are categorized into three groups based on ornamentation intensity: S1 (feeble ribs), S2 (well-visible ribs), and S3 (strong ribs). Statistical analysis (MANOVA) indicates significant differentiation in morphospace between the strong-rib group (S3) and the feeble-to-moderate rib groups (S1-S2), suggesting a covariation between rib strength and shell shape.

Kenneth De Baets@djbirddanerd· Jun 17

Acrothoracican bioerosion as evidence of Early Cretaceous barnacles (Cirripedia) in northwestern Gondwana @peerj.bsky.social peerj.com/articles/21433 #MarineBiology #Paleontology

Shell of the gryphaeid Ceratostreon boussingaulti.
(A) Left valve in ventral view. (B) Left valve in anterior view. (C) Right valve and umbo in dorsal view. (D, E) Close-up views of the borings of UR-CP-0585 cf. Rogerella. (E, F) Color maps of the borings of UR-CP-0585 cf. Rogerella showing the depth of the chambers. Abbreviations: H, high; L, low. Scale bar applies for (A)–(C).

Details and 3D volume reconstruction of UR-CP-0585 cf. Rogerella borings.
(A) Three-dimensional model of the shell of the gryphaeid Ceratostreon boussingaulti in ventral view, red rectangle indicates the area with the highest concentration of borings. (B, C) Close-up of the borings showing their overlap, close proximity, and the largest boring observed. (D, E) Micro-CT internal view and volume reconstruction of the chambers of cf. Rogerella (MorphoSource Media 000790704) with institutional catalog number UR-CP-0585 (F) Micro-CT reconstruction of the largest of the borings of UR-CP-0585 cf. Rogerella in apertural view. (G) Micro-CT reconstruction of the largest of the borings of UR-CP-0585 cf. Rogerella in transverse view. (H, I) Close-up of the borings of UR-CP-0585 cf. Rogerella indicating the numbering of at least 26 borings for which the length and width of the aperture were measured. Abbreviations: D, depth; L, length; W, width. Scale bar 2 cm applies to (H) and (I).

Kenneth De Baets@djbirddanerd· Jun 3

A new genus of #giant #salamander (Urodela, Cryptobranchidae) from the #Pliocene of #Japan - peerj.com/articles/213... @peerj.bsky.social #Paleontology #Taxonomy #Zoology #Fossils #Herpetology

Holotype fossil specimen LBM0142000335 of the newly described species Limnospondylus ajimuensis, shown in five anatomical views.

The image displays a vertebral fossil in dorsal (top-down), lateral (side), ventral (bottom), anterior (front), and posterior (back) views. Panel F provides a close-up of the zygapophyseal articular surface alongside an interpretative line drawing. Panel G shows CT scan cross-sections from anterior and posterior sections.

Red arrows highlight three diagnostic features: (1) strongly laterally elongated prezygapophyses, (2) broadly expanded and robust prezygapophysis bases, and (3) nearly straight alignment of the left and right transverse process ventral margins. The lateral view image is horizontally flipped to display opposite-side morphology. Scale bar indicates 2 cm.

Abbreviations used: ac (anterior canal), aco (anterior cotyle), cf (central foramen), fap (facies articularis prezygapophysialis), na (neural arch), nc (neural canal), pco (posterior cotyle), psz (postzygapophysis), prz (prezygapophysis), tp (transverse process), zgr (zygapophyseal growth rings). https://doi.org/10.7717/peerj.21362/fig-2

Scatter plots displaying Principal Component 1 (PC1) and Principal Component 2 (PC2) scores derived from a geometric morphometric analysis of trunk vertebrae.

Panel (A) shows the analysis based on the left lateral view of the vertebrae, while Panel (B) displays results from the dorsal half view. The plot distinguishes three groups using specific markers: a red star represents the Ajimu specimen (Limnospondylus ajimuensis), circles represent the extant species Andrias japonicus, and triangles represent Cryptobranchus alleganiensis. The distribution of these points illustrates the morphological variation and clustering among the fossil and modern salamander taxa. https://doi.org/10.7717/peerj.21362/fig-5

Graph comparing the ratio of centrum length to centrum height across living and extinct cryptobranchid salamander species.

The chart plots CL/CH ratios for both extant (currently living) and fossil specimens of the cryptobranchid salamander family, allowing comparison of vertebral proportions between modern and ancient species. https://doi.org/10.7717/peerj.21362/fig-4

Kenneth De Baets@djbirddanerd· May 1

🌊 Late #Pleistocene pelagic #gastropods of southern Taiwan🐚: paleobiodiversity, first #fossil records, and regional affinity: peerj.com/articles/210... @peerj.bsky.social #Biodiversity #Biogeography #Paleontology #Taxonomy, #Zoology

Species of the family Atlantidae from the Late Pleistocene Szekou Formation, Taiwan.
(A) Atlanta helicinoidea Gray, 1850, ASIZF0101104. (B and C) Atlanta rosea Gray, 1850, ASIZF0101105–106. (D) Atlanta tokiokai Van der Spoel & Troost, 1972, ASIZF0101107. (E) Atlanta vanderspoeli Wall-Palmer, Hegmann & Peijnenburg, 2019, ASIZF0101108. (F) Atlanta cf. peronii, ASIZF0101109. (G and H) Oxygyrus inflatus (Benson, 1835), ASIZF0101110–111. (I) Protatlanta sculpta (Issel, 1911), ASIZF0101112. Scale bars for A, B–C, D, E, F, G, H, I equal 1 mm. https://doi.org/10.7717/peerj.21046/fig-2

Species of families Creseidae, Cuvierinidae, and Cliidae from the Late Pleistocene Szekou Formation, Taiwan.
(A–C) Creseis acicula (Rang, 1828), ASIZF0101118–120. (D–F) Styliola subula (Quoy & Gaimard, 1827), ASIZF0101121–123. (G and H) Cuvierina sp., ASIZF0101124–125. (I) Clio convexa (Boas, 1886), ASIZF0101126. (J and K) Clio pyramidata (Linnaeus, 1767), ASIZF0101127–128. Scale bars for A, B, C, D, E–F, G–H, I, J, K equal 1 mm. https://doi.org/10.7717/peerj.21046/fig-5

Rarefaction curves of species diversity (Hill numbers) among three sampling localities.
(A) Species richness (0 D); (B) Shannon diversity (1 D); (C) Simpson diversity (2 D). Shaded areas represent 95% confidence interval for their respective sites based on 300 bootstrap replicates. https://doi.org/10.7717/peerj.21046/fig-10

Similarity relationships among Pleistocene holoplanktonic gastropod assemblages from the Indo–West Pacific.
(A) Cluster dendrogram based on presence–absence composition of assemblages using the Jaccard index and unweighted pair-group method with arithmetic mean (UPGMA); (B) principal coordinate analysis (PCoA) of the same presence–absence data based on the Jaccard index, showing the first two axes. https://doi.org/10.7717/peerj.21046/fig-11

Kenneth De Baets@djbirddanerd· Apr 25

In other cases, common sense, knowledge on anatomy and eye balling may be part of the process. It seems unlikely that whorl height in depicted ammonoid specimen jumped that rapidly in last whorl and it obviously correlates with a change in preservation and infilling: doi.org/10.7717/peer...

Holotype of Ivoites opitzi. Several sclerobionts can be seen encrusting specimen KGM 1983/147. Scale bar: 1 cm. Note the rapid jump in whorl height toward the end of the aperture and also the fluctuations in whorl height in 180 degrees related to tectonic deformation: https://doi.org/10.7717/peerj.3526/fig-2

Model of in vivo encrustation and subsequent compression and deformation on Ivoites opitzi. (1) orientation and conch morphology (in cross-section) of the specimen shortly after asymmetrical encrustation of first generation of epizoa (clusters D and E). (2) orientation and morphology of the specimen shortly after the asymmetrical encrustation of the second generation (cluster C) of epizoa (previous cluster of epizoa are currently lodged between the first and second whorl), (3) orientation and morphology of specimen when becoming encrusted with final epizoa (clusters A and B) or shortly before, (4) specimen after deformation; effect of deformation if specimen would have been initially planispirally coiled, effect in whorl section of specimen which was initially non-planispiral. https://doi.org/10.7717/peerj.3526/fig-8

Kenneth De Baets@djbirddanerd· Apr 25

In addition to many factors to consider in sizing modern forms, also differences in preservation and their retrodeformation/reconstruction need to be taken into account: doi.org/10.1186/s133...

Complete specimens of Passaloteuthis bisulcata from the early Toarcian, Tenuicostatum Zone, Semicelatum Subzone, Ohmden, Germany and the closest known relative of Megateuthis with known soft-tissue preservation. Both specimens were deformed, perhaps by predation or by compaction of oblique embedding (sinking rostrum first). Note that no scale bars were added in b and d because these are distorted versions of a and c. a Perhaps a female (a) because of the ten similar arms from the Museum Hauff (Holzmaden). c Perhaps a male (b) because of the large hooks from the Staatliches Museum für Naturkunde in Stuttgart, SMNS 70559). b and d show the same specimens retro-deformed with the approximate longitudinal proportions. More information in: https://doi.org/10.1186/s13358-024-00320-x

Kenneth De Baets@djbirddanerd· Apr 25

We estimated in more detail the size of the largest known belemnite Megateuthis based on comparison with its closest known relative Passaloteuthis showing rare soft-tissue preservation. With max estimated mantle length of min 1.33 m and possibly up to 1.76 m, it was among 10 largest modern species.

Reconstructions of Megateuthis elliptica combining two alternative assumptions for maximum rostrum length and maximum phragmocone diameter and of M. suevica using proportions of the soft tissue-specimens of Passaloteuthis. https://doi.org/10.1186/s13358-024-00320-x

A scene from the Germanic Basin during the Bajocian (e.g. in Germany, Luxembourg or Switzerland) with Megateuthis suevica catching a lytoceratid, a five-meter-long ophthalmosaurid like Argovisaurus, and nautilids in the background. These species co-existed in central Europe, but there is no direct evidence for their actual interactions. https://doi.org/10.1186/s13358-024-00320-x

Kenneth De Baets@djbirddanerd· Apr 25

We know for example that Vampyromorpha (where more data is available) markedly changed their body proportions and ecology since the Mesozoic. See reconstruction of Jurassic Vampyromorpha in our paper based on available soft-tissues with large mantle and small head/arms: doi.org/10.1186/s133...

Reconstruction of the Toarcian Jeletzkyteuthis coriacea catching a smaller specimen of Parabelopeltis flexuosa.

Kenneth De Baets@djbirddanerd· Apr 14

#Body reconstruction and #size estimation of #plesiosaurs by Ruizhe Jackevan Zhao: peerj.com/articles/21146 in @peerj.bsky.social relevant to #EvolutionaryStudies #MathematicalBiology #Paleontology #Zoology

he workflow for establishing a hybrid framework to estimate body mass in plesiosaurs.
(A) Acquire data from fossil specimens (illustrated here using the modified image of Sachicasaurus vitae, Paramo-Fonseca, Benavides-Cabra & Gutierrez, 2018, CC BY 4.0). (B) Create lateral-view silhouettes of skeletal elements. (C) Estimate the dimensions of missing fossil elements through regression formulae and/or comparisons with closely related taxa. (D) Reconstruct the main body axis, including the dimensions and shape of the skull and vertebral column. (E) Reconstruct the ribcage in both lateral view and transverse cross-sections jointly, then restore the soft-tissue outlines of the main body axis and the flippers. (F) Estimate the body mass using the cross-sectional method (Zhao, 2024). (G) Establish body mass equations from the mass estimates of multiple species. Elements in this figure are not to scale. https://doi.org/10.7717/peerj.21146/fig-1

Silhouettes of representative plesiosaur models from different clades, showing the reconstructed body outlines and transverse cross-sections.
All models are scaled to the same length. (A) Thalassomedon haningtoni. (B) Aristonectes quiriquinensis. (C) Sachicasaurus vitae. (D) Liopleurodon ferox (E) Abyssosaurus nataliae. (F) Cryptoclidus eurymerus. (G) Martinectes bonneri. (H) Polycotylus latipinnis. (I) Meyerasaurus victor. (J) Macroplata tenuiceps. (K) Seeleyosaurus guilelmiimperatoris. (L) Microcleidus tournemirensis. (M) Nichollssaura borealis. (N) Brancasaurus brancai. (O) Plesiopterys wildi. https://doi.org/10.7717/peerj.21146/fig-4

Representative plesiosaur reconstructions created in this study.
(A) Kronosaurus queenslandicus. (B) Albertonectes vanderveldei. (C) Aristonectes quiriquinensis. (D) Plesiopterys wildi. (E) Brancasaurus brancai. (F) Liopleurodon ferox. (G) Seeleyosaurus guilelmiimperatoris. (H) Meyerasaurus victor. (I) Cryptoclidus eurymerus. (J) Mauriciosaurus fernandezi. All limbs are vertically oriented for display. The dorsal ribs in these skeletal reconstructions have been aesthetically refined and thus differ from the initial versions used to infer ribcage cross-sections. Scale bar equals 1 m. https://doi.org/10.7717/peerj.21146/fig-5

Scatter plot and regression models of the pruned skull-neck dataset.
The red curve, green dashed line, and the blue dotted line represent the nonlinear regression model based on a log–logistic (LL) function, the Ordinary Least Squares (OLS) model, and the Phylogenetic Generalized Least Squares (PGLS) model, respectively. Lower values of sample-size corrected Akaike Information Criterion (AICc) and mean per cent prediction error (∣%PE∣) represent better model performance. https://doi.org/10.7717/peerj.21146/fig-8

Kenneth De Baets@djbirddanerd· Mar 25

A new #Triassic austrolimulid from #Poland presents insight into xiphosurid evolution and palaeobiogeography at the dawn of the Mesozoic led by @jaudycki.bsky.social and with @grzegorzniedz.bsky.social: peerj.com/articles/209... @peerj.bsky.social #paleobiology #evolution

Idealized reconstruction of Polonolimulus zaleziankensis gen. et sp. nov.
Reconstruction credit: Jonatan Audycki. https://doi.org/10.7717/peerj.20950/fig-11

Palaeobiogeography of Triassic horseshoe crabs.
Palaeogeography of the world is reconstructed at 245 Ma (Anisian, Middle Triassic) and displayed using Mollweide projection, with a close-up of the Central European Basin System. The extents of shallow seas (light blue), landmasses (pale yellow) and mountain ranges (orange) are reconstructed based on Cao et al. (2017). Symbols represent Triassic localities that have yielded horseshoe crab fossils, their ages, and taxonomic assignment. The palaecoordinates of the xiphosurid localities are also reconstructed at 245 Ma for consistency. Simplified reconstructions of austrolimulids are displayed for context and comparison: 1–Polonolimulus zaleziankensis from the Lower Triassic (uppermost Induan/lowermost Olenekian) Zalezianka-Gózd locality, Poland; 2–Psammolimulus gottingensis from the Lower Triassic (Olenekian) Solling Formation, Germany; 3–Batracholimulus fuchsbergensis from the Upper Triassic (Norian/Rhaetian boundary) Exter Formation, Germany; 4–Attenborolimulus superspinosus from the Lower Triassic (upper Olenekian) Petropavlovka Formation, Russia; 5–Vaderlimulus tricki from the Lower Triassic (lower Spathian, Olenekian) Thaynes Group, USA; 6–Austrolimulus fletcheri from the Middle Triassic (lower Anisian) Beacon Hill Quarry, Hawkesbury Sandstone, Australia; 7–Dubbolimulus peetae from the Middle Triassic (lower Anisian) Ballimore Formation, Australia; 8–Tasmaniolimulus patersoni from the Lower Triassic (lower Induan) Jackey Shale, Tasmania (Australia). Since the investigated xiphosurid localities differ stratigraphically, their geographical position relative to continental boundaries and shallow seashores are approximated. The display window on the map showing close-up boundaries is not square due to employed map projection. For the full list of investigated localities along with their current and reconstructed palaeocoordinates and temporal data. https://doi.org/10.7717/peerj.20950/fig-10

PCA plot of the Triassic horseshoe crabs using prosomal data only.
TPS grids show deformation between the average and the minimum and maximum landmark coordinates for PC1 and PC2. Convex hulls for Austrolimulidae (red) and Limulidae (light blue) are plotted in two alternative ways: solid lines for the inclusion of Limulitella is in Limulidae, and dashed lines if Limulitella is included within Austrolimulidae. Outlines of the specimens used in the analysis are shown above the plot: 1–AM F38274 Austrolimulus fletcheri, 2–gz4142 (latex peel of the holotype Muz. PGI 1808.II.10) Polonolimulus zaleziankensis, 3–UCM 140.25 Vaderlimulus tricki, 4–MMF 27693 Dubbolimulus peetae, 5–GZG.INV.45730a Psammolimulus gottingensis, 6–PIN 5640/220 Attenborolimulus superspinosus, 7–UNISTRA.2015.0.50968 Limulitella bronni, 8–LIM 68 L. bronni, 9–ZPAL V.46/101 Limulitella tejraensis, 10–PMSL T-993 Sloveniolimulus rudkini, 11–MGSB M 262 Tarracolimulus rieki, 12–MGSB 19195 Heterolimulus gadeai.: 13–MAN 8240 Keuperlimulus vicensis, 14–ZPAL V.46/120 Limulitella tejraensis, 15–MB.A.0207 Limulidae indet. (‘Limulus kieri’), 16–ZPAL V.46/106 L. tejraensis, 17–SNSB-BSPG 1967 XVI 27 Limulitella cf. liasokeuperinus, 18–ZPAL V.46/103p L. tejraensis , 19–UTGD 123979 Tasmaniolimulus patersoni. Outlines are not to scale. https://doi.org/10.7717/peerj.20950/fig-9

Kenneth De Baets@djbirddanerd· Feb 17

Digesting an ancient ecosystem: #coprolites from the Grippia #bonebed, Lower #Triassic, Svalbard peerj.com/articles/207... @peerj.bsky.social #paleobiology #paleontology #fossils doi.org/10.7717/peer...

Photographs (A–C) and CT-scans (D–G) of morphotype E.
(A) The complete specimen with x-y being cross section in picture F. (B–C) Orthoceratoid cephalopod shell fragment seen in two different angles. Red arrows pointing to the same spot in both pictures. (B) Shell fragment seen from the top. (C) Shell fragment seen in cross section. (D–E) Orthoceratoid shell fragment with a length of 15.8 mm and visible chambers. (D) Outside of the shell fragment. (E) Underside of the shell fragment. (F) Orthoslice of onychites marked x-y in picture A. (G) Bone fragment. (A–F) PMO 250.281. (G) PMO 250.904. https://doi.org/10.7717/peerj.20746/fig-7

CT-scans (A, D, G–I) and thin sections (B–C, E–F) of morphotype A.
(A1–A2) External and internal view of sub-morphotype A, PMO 250.270. (B) Tetrapod bone in thin section, PMO 250.004. (C) Fish vertebrae, PMO 250.009. (D1–D2) External and internal view of sub-morphotype A2, PMO 150.275. (E) Fish scale, PMO 249.999. (F) Degraded bone fragments, PMO 250.000. (G1–G2) External and internal view of sub-morphotype A3, PMO 250.273. (H) Burrows with a width of approximately 0.5 mm over a total area of three mm, PMO 250.530. (I) Conodont element measuring 1.22 mm in length, PMO 250.273. https://doi.org/10.7717/peerj.20746/fig-3

Photographs of the different morphotypes found in the Grippia bonebed, Svalbard.
(A–B) morphotype A1 cigar. (C–E) morphotype A2 amphipolar. (F–G) morphotype A3 cylindrical with grooves. (H–J) morphotype B1 spiral rounded. (K–L) morphotype B2 teardrop. (M–N) morphotype C sub-rounded. (O-P) morphotype D reniform. (Q–S) morphotype E wide cylindrical.(A) PMO 250.847. (B) PMO 250.846. (C) PMO 250.275. (D) PMO 250.854. (E) PMO 250.858. (F) PMO 250.860. (G) PMO 250.530. (H) PMO 250.533. (I’-I”) PMO 250.864. (J) PMO 250.841. (K) PMO 250.869. (L) PMO 250.868. (M) PMO 250.271. (N) PMO 250.884. (O) PMO 250.886. (P) PMO 250.528. (Q) PMO 250.899. (R) PMO 250.897. (S) PMO 250.281. https://doi.org/10.7717/peerj.20746/fig-2

Kenneth De Baets@djbirddanerd· Feb 13

I agree. I somehow had to think about this cartoon involving petrified trees.

At first I was afraid, I was petrified fossil tree cartoon. Source: https://www.reddit.com/r/PeterExplainsTheJoke/comments/1jcm6j5/_/#lightbox

Kenneth De Baets@djbirddanerd· Feb 3

Paleoecological insights from #coprolites and their inclusions from the #Permian Rio do Rasto Formation, #Brazil: doi.org/10.1016/j.pa... 97 samples with fish, plant, insect, bone inclusions and microorganisms and parasites Download it here for limited time: authors.elsevier.com/c/1mYVo,gYwh...

Fig. 3. Coprolites morphotypes (A–D) and their proportion (E). (A) Heteropolar (UFRGS-PV-0535-P). (B) Amphipolar (UFRGS-PV-0374-P). (C) Indeterminate spiral (UFRGS-PV-0750a-P). (D) Non-spiral (UFRGS-PV-0741c-P). (E) Graphic showing the proportion of morphotypes found in the studied sites (N = 97). Scale bars = 5 mm (A–C), 1 mm (D).

Comparison of the size of non-alimentary inclusions found in the coprolites.

Kenneth De Baets@djbirddanerd· Jan 9

A highly diverse Pennsylvanian #tetrapod ichnoassemblage from the Semily Formation (Krkonoše Piedmont Basin, Czechia) peerj.com/articles/204... @peerj.bsky.social #ichnology #paleontology #paleobiology

A series of blockdiagrams illustrating the development (from the phase 1 to phase 3) of the Ploužnice Lake as interpreted from the studied sections (Kyje–Ploužnice railway cut, Štikov roadcut) and data on the Ploužnice Horizon by Blecha et al. (1997). The alternation of wet and dry climate phases that controlled the extent of the Ploužnice Lake, has already been interpreted from contemporaneous deposits of the Líně Formation in central Bohemia (Nádaskay et al., 2025). Close-ups provide a detailed interpretation of the depositional environment in which the trackmakers roamed and left their trace fossils.

Kenneth De Baets@djbirddanerd· Dec 4

Up-to-date data reshape our understanding. For the Permian–Triassic, the new vetted dataset (hal.science/hal-04951445v5) shows diversity trends that differ sharply from PBDB, highlighting how exhaustive, expert-curated compilations can dramatically change interpretations of extinction and recovery.

Evolution of the taxonomic richness of Late Permian-Early Triassic conodonts comparing the present database and the PaleoBiology Database (PBDB). The metric used here is the raw counting (sample in bin) of conodont species. PBDB data extracted with the R package PaleoDiv (Nau 2025) on 06/25/2025 and the raw data are available on the GitHub repository in the folder Datapaper_PCI Paleo. The time scale was built with divDyn R package (Kocsis et al. 2019) but the absolute ages are from Leu et al. (2025). Abbreviations: Gr – Griesbachian; Di – Dienerian. https://hal.science/hal-04951445v5

Kenneth De Baets@djbirddanerd· Nov 12

Decoding the bare necessities of decapod crustacean nomenclature through the ages peerj.com/articles/203... @peerj.bsky.social