Kenneth De Baets
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djbirddanerd.bsky.social
Kenneth De Baets
@djbirddanerd.bsky.social
620 followers 940 following 160 posts
Paleobiologist @IBE_Warszawa into cephalopods, parasites, funny tees and movies; Paleontology/Evolution Section Editor @PeerJLife
; previously @palaeofau. Avatar after Jacek Yerka also on @[email protected]
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djbirddanerd.bsky.social
Decoding the bare necessities of decapod crustacean nomenclature through the ages

peerj.com/articles/203...

@peerj.bsky.social
Total number (1758–2024) of etymologies. Etymologies are displayed by category as both raw counts and relative percentages of the overall dataset. https://doi.org/10.7717/peerj.20337/fig-1 Temporal variations in the relative proportion of etymologies. A generalised additive model was applied, showing the predicted trend and 95% confidence interval. https://doi.org/10.7717/peerj.20337/fig-2
November 12, 2025 at 12:21 PM
djbirddanerd.bsky.social
From trace to trace maker: #Oligocene–Miocene #coprolites of southern #Poland and their potential #producers

peerj.com/articles/202...

@peerj.bsky.social
Examples of coprolites collected in the Oligocene and Miocene marine sediments of Poland. Kąkolówka I: (A) GIUS 10–3796/O/2. Curved morphotype; (B) GIUS 10–3796/O/7. Curved morphotype; (C) GIUS 10–3796/O/23. Sinusoidal morphotype; Kąkolówka II: (D) GIUS 10–3796/O/154. Sinusoidal morphotype; (E) GIUS 10–3796/O/181. Sinusoidal morphotype; (F) Kąkolowka I, GIUS 10–3796/O/60. Curved morphotype; (G) Kąkolówka I, GIUS 10–3796/O/77. Curved morphotype; Wola Czudecka: (H) GIUS 10–3796/O/251. Elongated morphotype; (I) GIUS 10–3796/O/253. Elongated morphotype; (J) GIUS 10–3796/O/259. Elongated morphotype; (K) GIUS 10–3796/O/274. Elongated morphotype; (L) Futoma, GIUS 10–3796/O/279. Oval morphotype; (M) Futoma, GIUS 10–3796/O/282. Irregular morphotype; Kąkolówka I: (N) GIUS 10–3796/O/96. Irregular morphotype; (O) GIUS 10–3796/O/98. Irregular morphotype; (P) GIUS 10–3796/O/107. S-shaped morphotype; (R) GIUS 10–3796/O/111. S-shaped morphotype; (S) GIUS 10–3796/O/135. S-shaped morphotype; (T) Jamna Dolna, GIUS 10–3796/O/294. Elongated morphotype; (U) Kąkolówka I, GIUS 10–3796/O/139. Oval morphotype. Scale bars five mm. https://doi.org/10.7717/peerj.20242/fig-2 Recent faeces. (A) Brown hare (Lepus europeaus). (B) European mole (Talpa europaea). (C) Guinea pig (Cavia porcellus). (D) Swinhoe’s striped squirrel (Tamiops swinhoei). (E) Seba’s short-tailed bat (Carollia perspicillata). (F) House sparrow (Passer domesticus). (G) Syngnathidae. (H) City pigeon (Columba livia forma urbana). (I) Great barracuda ( Sphyraena barracuda). (J) Hermit crab ( Coenobita brevimanus). (K) Flying crab (Liocarcincus holsatus). (L) Seacucumber (Holothuria sp.; redrawn from Knaust & Hoffmann, 2020). (M) Cephalopod (Nautilus pompilius; redrawn from Knaust & Hoffmann, 2020). (N) Perciformes. Scale bars one cm. https://doi.org/10.7717/peerj.20242/fig-6
November 3, 2025 at 10:26 AM
djbirddanerd.bsky.social
Biogeography after #Permian #Triassic boundary crisis resulted from a complex combination of functional and dispersal mechanisms doi.org/10.18261/let...

#Ammonoids limited by #dispersal in Griesbachian/Spathian, by niche in Smithian; #conodonts by #niche in Griesbachian, mixed in Dienerian–Spathian
Fig. 1. Palaeo-location of the 27 regions of A) conodont and B) ammonoid taxa taxa defined in this study, respectively. Each region is associated to its number of sampled localities encircled by five arcs, each arc corresponding to a time interval (Changhsingian, Griesbachian, Dienerian, Smithian, or Spathian). A coloured arc means that the region includes at least one locality dated from this time interval; an unfilled arc means that the region does not include any locality dated from this time interval. See the section Material and methods for details about the calculation of the palaeocoordinates. Silhouettes of conodont and ammonoid are public-domain images from the Phylopic website (compare https://doi.org/10.18261/let.58.3.2). Values of Dispersal-Niche Continuum Index (DNCI) show ammonoid biogeography was dispersal-constrained in Griensbachian and Spathian as opposed to niche constrained in the Smithian, while conodonts were more functionally (niche) constrained in Griesbachian as opposed to driven by both niche and dispersal constraints from the Dienerian to Spathian. Black dots and associated horizontal black lines represent mean value and ±2 standard error, respectively.
October 29, 2025 at 9:15 AM
djbirddanerd.bsky.social
It was a pleasure to review this work. I highly recommend it for everyone interested in phylogenetic and macroevolutionary inferences from fossil data. It is available #OpenAccess:
doi.org/10.1111/pala...
Character evolution model configurations. Model configurations correspond to a range of simple to increasingly complex and parameter-rich models of morphological evolution. A, model S, strict morphological clock of discrete morphological data with equal rates of change among characters. B, model R, allows for rate variation among characters and across phylogeny. C, model R + E, builds on model R with traits identified as ecologic vs non-ecological characters assigned to different character partitions. D, model RE + C, builds on R + E but with continuous characters evolving according to a single-rate Brownian motion process. E, model mREC, modifies model RE + C such that continuous characters evolve according to a multi-rate Brownian motion process.
October 29, 2025 at 8:29 AM
djbirddanerd.bsky.social
Lin & O’Dea show #Remarkable #dominance of #myctophid #otoliths in Upper #Miocene Chagres Formation, #Caribbean #Panama: doi.org/10.7717/peer...
#Biodiversity suggests pre-Isthmus #upwelling with efficient transfer from high #PrimaryProduction to predators shaping Ecosystem. #Paleontology #Taxonomy
Reconstruction of Late Miocene mesopelagic fish-dominated ecosystem in Caribbean Panama. The illustration highlights key taxa, including lanternfish, hatchetfish, billfish, Isistius sharks, Otodus megalodon, Isthminia panamensis, and Lepidochelys sea turtle. Artwork by Yun-Kae Kiang. https://doi.org/10.7717/peerj.20155/fig-18 Otoliths of Diaphus (Myctophidae) from the Upper Miocene Chagres Formation, Caribbean Panama. (A–C) Diaphus aequalis Schwarzhans & Aguliera, 2013, ASIZF 0100963–0965. (D–F) Diaphus apalus Schwarzhans & Aguliera, 2013, ASIZF 0100966–0968. (G–K) Diaphus barrigonensis Schwarzhans & Aguliera, 2013, ASIZF 0100969–0973. (L–O) Diaphus dumerilii (Bleeker, 1856), ASIZF 0100974–0977. Images are inner views. Scale bar = one mm.
October 17, 2025 at 10:31 AM
djbirddanerd.bsky.social
The first #leech body #fossil predates estimated hirudinidan origins by 200 million years

peerj.com/articles/199...

@peerj.bsky.social #Annelida
October 2, 2025 at 2:15 PM
djbirddanerd.bsky.social
1st chapter by Klug et al. (2015) dealt with technical #terms and #qualitative to #quantitative aspects when "Describing #Ammonoid Conchs": doi.org/10.1007/978-...

Recommendations seem to have been embraced in Paleozoic (doi.org/10.5252/geod...) to Mesozoic (doi.org/10.1016/j.cr...) communities
October 1, 2025 at 1:34 PM
djbirddanerd.bsky.social
In other cases, predators may be less successful in concentrating belemnite remains and (mass) #mortality at #spawning grounds after #reproduction may concentrate belemnite rostra. This is the basic of another model developed by Doyle and Macdonald (1993): doi.org/10.1111/j.15...
Fig. 7. Conceptual model for the Antarctic battlefield where accumulation and concentration processes at the shallow-marine spawning ground may contribute to forming dense concentrations of belemnites. See Doyle and Macdonald: https://doi.org/10.1111/j.1502-3931.1993.tb01513.x One in a million example of pabulite where belemnite which was bitten in half by a predator and subsequently dropped still preserved its arm crown and a prey item grasped within it. See: https://doi.org/10.1186/s13358-021-00225-z
August 29, 2025 at 3:13 PM
djbirddanerd.bsky.social
In the #predation concentration model, #bromalites = fossilized remains of material sources from the digestive system of predators (regurgitates, gastric masses) may play an important role in concentrating belemnite rostra. The Hybodus #shark specimen shows this quite nicely: doi.org/10.1186/s133...
Conceptual model of predation concentration accumulates showing how gastric masses or regurgitates may contribute to concentrating belemnite rostra or other cephalopod elements (note magnified arm hook). From Doyle and Macdonald (1993): https://doi.org/10.1111/j.1502-3931.1993.tb01513.x The Early Jurassic elasmobranch Hybodus hauffianus with its stomach clogged by belemnite rostra (SMNS 10062) from the Toarcian Posidonia Shale of Holzmaden, Germany. See: https://doi.org/10.1186/s13358-021-00225-z
August 29, 2025 at 3:13 PM
djbirddanerd.bsky.social
Talking about another true #invertefest: belemnite "battlefields" or "Schlachtfelder". Despite the name, they are generally used to refer to dense accumulations of #fossil #cephalopod rostra, which can be formed under various mechanisms. Irrespectively, they are a great way to obtain large samples.
A dense accumulation of fossil belemnite rostra (including also some encrusting bivalves) from the Pliensbachian-Toarcian GSSP of Peniche Portugal (see https://doi.org/10.1098/rsos.190494).
August 29, 2025 at 10:50 AM
djbirddanerd.bsky.social
I´m Kenneth. I am a paleontologist at the University of Warsaw. Our team works on the evolution and fossil record of mollusks and wormy parasites. This includes looking at shell morphology, traces and pathologies in skeletons as well as fossilized poop and other fossils. www.paradivelab.com
Members of our team and collaborators working on fossil (shark) coprolites from the Permian at the Institute of Evolutionary Biology in Warsaw. Belemnite accumulation (or battlefield) at the Pliensbachian-Toarcian GSSP in Peniche, Portugal Life reconstruction of ammonoid Carboniferous assemblages including various ontogenetic stages. The reconstruction was made by Christian Klug for our paper which you can find at the following url: https://doi.org/10.4202/app.00220.2015
August 22, 2025 at 11:31 AM
djbirddanerd.bsky.social
🐙 Key evolutionary insights:

• Different lineages show distinct long-term size #trends
• Responses to mass extinctions varied
• Most groups evolved giants >1 m ( #marine #megafauna)
• Size ceilings: ~100 L for nautilids/orthocones vs. ~500 L for ammonoids/neocoleoids

See: doi.org/10.1038/s415...
Exponential trendlines of the volumes of the four examined cephalopod groups through the Phanerozoic. Horizontal bars display the duration of the four groups. Red lines represent mass extinctions. Maximum body sizes in volumes through the Phanerozoic and the European rock record (brown line).
August 21, 2025 at 4:05 PM
djbirddanerd.bsky.social
🌊🦑 For 500+ million years, #cephalopods have shaped ocean ecosystems as active predators.
In our study, we trace body #size fluctuations of cephalopods—from ancient shelled cephalopods to today’s squids & octopuses—using maximum body volume for comparability across groups. doi.org/10.1038/s415...
Some of the largest known cephalopods as examples for the four studied groups. a, Endoceras giganteum, UMMNH 2019.0385, Platteville, Illinois (display in the University of Michigan Museum of Natural History). b, Deiroceras hollardi, PIMUZ 31922, Early Devonian, Jebel Mdouar, Morocco (display in the Museum of Natural History, University of Zurich). c, Cenoceras rumelangense, Bajocian, Dorset, UK (W. Grulke collection). d, ventral and e, lateral view of Parapuzosia seppenradensis, Campanian, Seppenrade, Germany, displayed at the LWL museum in Münster. f, Megateuthis elliptica, SMNS 60752, Bajocian, Bopfingen-Oberdorf; Germany (display at the Staatliches Museum für Naturkunde, Stuttgart). g, Leptotheutis gigas, Tithonian, Solnhofen (display in the Schaulager Ruhrmuseum, Essen). All photos except a belong to CK. Photo in a by courtesy of J. Bauer (University of Michigan Museum of Natural History). Maximum body sizes in lengths and diameters through the Phanerozoic. a, linear plot. Grey silhouette of a 1.8 m tall person for scale. b, logarithmic plot. c, environmental parameters such as sea-level and sea surface temperatures (blue lines) and the European rock record (brown line). Red lines represent mass extinctions.
August 21, 2025 at 4:05 PM
djbirddanerd.bsky.social
Our study examines historical & modern examples, proposes hosts can ease transitions, and links such shifts to diversification, with implications for biodiversity under global change. doi.org/10.1093/icb/...
Phylogenetic relationships and divergence time estimates of Platyhelminthes (modified from Perkins 2010), Pentastomida (Raillietiellida and Porocephalida; modified from Sanders and Lee 2010), Nematoida (modified from Blaxter 2009; Rota-Stabelli et al. 2013; Li et al. 2018), and constraints for colonization of particular environments (full circles = fossil or modern observations; stippled circles = inferred habitat based on modern clock or host constraints). Arrows denote ancestral environmental transitions. “ “ refer to paraphyletic lineages. Fossil constraints reviewed in De Baets et al. (2021). Repeated transitions between marine and freshwater environments in cestodes belonging to the order Bothriocephalidea. Note propensity for more transitions from freshwater to marine hosts (modified from Brabec et al. 2015).
August 13, 2025 at 3:34 PM
djbirddanerd.bsky.social
Final days (Deadline: August 15) to apply for a 4-year #PhD position to work on inclusions in Permian-Triassic coprolites and how they can inform us on the impact of mass #extinction of parasite-host associations.
Reconstruction of Ascarites by @Franzanth - an egg attributed to Ascaridae known since the Triassic.
August 12, 2025 at 9:39 AM
djbirddanerd.bsky.social
The answer is both fossil types are #underdogs to study #evolution and i discovered parasitic remains in #ammonoid shell pathologies during my PhD research: doi.org/10.4202/app..... I saw the potential in both; one things led to another. Now i am a #malacologist and a #paleoparasitologist
Longitudinal median section through the well preserved specimen PIMUZ 28583 of Sellanarcestes spp. (Sellanarcestes wenkenbachi Zone, Emsian, Oufrane, Morocco) displaying many “Housean pits” interpreted as blister pearls, many with internal tube.
May 21, 2025 at 8:55 AM
djbirddanerd.bsky.social
Taphonomic and reworking processes isolating #cephalopod septa and chamber #fillings: doi.org/10.18261/let...

#paleontology #paleobiology #taphonomy #phragmocone #cephalopods
Fig. 13. Illustration of some of the taphonomic processes discussed with images of the fossil results. a, b, Early Devonian of the Tafilalt, Morocco. c, Middle Triassic of central Europe. d, Middle Jurassic of the Causses, France. e, Early Cretaceous of Heligoland, Germany. https://doi.org/10.18261/let.58.2.1
April 29, 2025 at 1:10 PM
djbirddanerd.bsky.social
Perturbations in plate #microstructure and the overproduction of skeletal material in specific regions, together with reduced #size, negatively impact the host’s #growth suggesting a parasitic interaction. rdcu.be/ei75y
Comparative distribution of centroid size among non-infested (“normal”) and infested echinoderm plates (a) and among the different number of outgrowths per plate (b). A box shows the interquartile range (IQR) of the distribution of a data subset and the whiskers the 1.5 IQR value. Vertical colored lines show the median centroid size for each subset.
April 24, 2025 at 2:49 PM
djbirddanerd.bsky.social
These unusual #structures have not been previously documented from #Cambrian echinoderms and their lack of #consistency across various morphological parameters, supports the interpretation that a #biotic interaction generated these unique structures. rdcu.be/ei75y
CT-based 3D reconstruction of the internal microstructure of stereom showing microstructural difference between a plate and its associated outgrowths. (a) Specimen USTL5296, echinoderm plate displaying three outgrowths of different size (labelled O1, O2 and O3), with virtual orthogonal plans X, Y and Z. (b) Axial-section of O2 according to plan Y. (c) Axial-section of O3 according to plan Y. (d) Axial-section of O1 according to plan Z. (e) Cross-section of O1 at its base according to plan X, showing microstructural difference. (f) Specimen USTL5298-6 echinoderm plate displaying three outgrowths of different size. (g) Cross-sections of O1, O2 and O3, at their base, according to plan X, showing microstructural difference. (h) Axial-section through the pit of O2 and subaxial section of O1 according to plan Y. (i) Axial-section of O3 according to plan Y. Red arrows point to microstructural difference at the base of each outgrowth. O1 = outgrowth 1; O2 = outgrowth 2; O3 = outgrowth 3. Scale bars, 500 μm (a, e); 50 μm (b–d, f–h).
April 24, 2025 at 2:49 PM
djbirddanerd.bsky.social
Based on qualitative and quantitative analyses, we report evidence of a biotic interaction between an echinoderm host and its symbiont, probably a parasitic epibiont, from the Cambrian Wuliuan Stage of Australia. The echinoderm plates bear external outgrowths with a median pit at their distal end.
Outgrowth structures on Cambrian disarticulated echinoderm plates of different size and shape. (a) Specimen USTL5297-5, plate fragment displaying three outgrowths, one being longitudinally sectioned at fragment edge. (b) Close-up on the cut outgrowth from specimen USTL5297-5. (c) Specimen USTL5297-11, plate with flat edge displaying two outgrowths of similar size and shape. (d–f) Specimen USTL5300-15, plate displaying two outgrowths of different size (close-up on each outgrowth in (d), (f). (g–h) Specimen USTL5301-4, plate displaying one tall outgrowth, with a close-up (h). (i–l) specimen USTL5298-7, plate displaying three outgrowths of different size and shape, each outgrowth with a close-up (j–l). White arrows point to outgrowths. Yellow arrow points to pit within the outgrowth. Scale bars, 500 μm (a, c); 100 μm (c, d–j). https://rdcu.be/ei75y
April 24, 2025 at 2:49 PM
djbirddanerd.bsky.social
Further evidence to test these hypotheses could be obtained by conducting systematic screenings for resistant remains of platyhelminths such as hooks and eggs as well as characteristic traces such as trails or shell concretions preserved with their producers.
Table highlighting the possible (hollow circles) and realized (filled circles) preservation potential of structures in the fossil record modified and mainly expanded from these references (Rieger and Sterrer 1975, Littlewood and Donovan 2003, Knaust 2010, De Baets et al. 2021a, 2021b). In-depth discussion of these points and associated references can be found in the main text (https://doi.org/10.1590/S1984-4689.v41.e24002). Question marks relate to a structure likely having increased preservation potential but further documentation is needed. Asterisks refers to packaging of eggs may further increase resistance of egg capsules.
December 6, 2024 at 9:40 PM
djbirddanerd.bsky.social
This relative order of appearance is most consistent with the hypotheses placing the divergence of Monopisthocotylea from the rest of Neodermata before the divergence of Cestoda from a clade of Trematoda and Polyopisthocotylea.
Alternative topologies obtained for Neodermata in analyses of Brabec et al. (2023). Circles indicate the oldest fossil record for particular groups (differently coloured circles reflect those for early to later branching groups in Fig. 2). Light gray tree branches reflect lacking fossil record, black bars reflect present fossil record. Circle within circle refers to origin of endoparasitism and smaller circle attached to larger circle refers to origin of ectoparasitism based on fossil record. See Table 1 and discussion in text (https://doi.org/10.1590/S1984-4689.v41.e24002) for further details of the oldest finds. Note the different stratigraphic range and distribution of ghost lineages depending on the topology.
December 6, 2024 at 9:40 PM
djbirddanerd.bsky.social
Species/genera attributable to modern families could not be confidently traced back beyond the #Quaternary with the exception of #Gymnophallidae (if we consider traces characteristic for them today to be equally characteristic in the deep time). doi.org/10.1590/S198...
Earliest direct archaeological finds of families of parasitic platyhelminths from Pleistocene (c. 2.58 Ma - 11.7 Ka, yellow labels) and Holocene (< 11.7 Ka, white labels). Sites numbered in chronological order; age in years Before Present (yrs BP); age scale bar pertains to Holocene finds. See Table 2 in https://doi.org/10.1590/S1984-4689.v41.e24002 for further details of each find.
December 6, 2024 at 3:15 PM
djbirddanerd.bsky.social
The fossil finds are surprising for #trematodes which so far are recovered from #terrestrial/freshwater environments older than from #marine environments both in the case of eggs in vertebrate coprolites or characteristic traces in bivalve shells.
Summary of the stratigraphic occurrence of characteristic igloo-shaped and pit-shaped structures attributed to gymnophallid trematodes. Question mark refers to a superficially similar igloo structure discussed in text which is superficially similar but lacks diagnostic characters to make it clearly assignable to trematodes. See text for further details. https://doi.org/10.1590/S1984-4689.v41.e24002
December 6, 2024 at 3:10 PM
djbirddanerd.bsky.social
Although the #fossil record is patchy and some clades lack one, the finds which are available are surprisingly concordant with some of the latest molecular #phylogenies (free-living forms > Monopisthocotylea > Cestoda > Trematoda) 10.0.3.248/j.cub.2023.0...
Stratigraphic occurrence of fossil evidence for particular orders of Platyhelminthes (https://doi.org/10.1590/S1984-4689.v41.e24002). Phylogeny follows Littlewood and Waeschenbach (2015) with the exception of Neodermata which follows Brabec et al. (2023). See Table 1 and text for further details of each find.
December 6, 2024 at 3:10 PM