[Paleontology • 2026] Tanyka amnicola • An aberrant Stem Tetrapod from the early Permian of Brazil

 

Tanyka amnicola

 Pardo, Marsicano, Smith, Cisneros, Angielczyk, Fröbisch, Kammerer & Richter, 2026

 

DOI: doi.org/10.1098/rspb.2025.2106

Illustration by Vitor Silva

Abstract

Early evolutionary history of tetrapods is typically divided into two major phases: an initial diversification of archaic stem tetrapod groups, and a sudden replacement by temnospondyl amphibians and amniotes following a late Carboniferous dry interval termed the Carboniferous Rainforest Collapse (CRC). However, the degree to which this scenario applies to the early tetrapods of Gondwana is uncertain. Here, we report Tanyka amnicola, gen. et sp. nov., an archaic stem tetrapod from the early Permian of Brazil characterized by strong torsion of the mandibular ramus and a remarkable battery of enlarged denticles on a strongly arched coronoid. The new taxon is assigned to the tetrapod stem based on the presence of a denticulate adsymphyseal and elevated hook-like glenoid surface without a postglenoid area. Phylogenetic analysis shows affinities between this species and stem tetrapods more proximal to the tetrapod crown group, particularly Eucritta and the Laurussian baphetids. This is the second stem tetrapod group known to have survived until the end of the early Permian in Gondwana despite local extirpation in Laurussia, implying that current hypotheses of Carboniferous tetrapod turnover are oversimplified. The unique jaw morphology suggests adaptations to either specialized processing of small invertebrates or consumption of some plant material, demonstrating that stem tetrapods continued to explore new niche space into the Permian of Gondwana.

Keywords: Permian, Tetrapoda, palaeobiogeography

Holotype jaw of Tanyka amnicola, MAP-PV 662.
(a) MAP-PV 662 in dorsal view; (b) interpretive drawing of MAP-PV 662 in dorsal view;
(c) MAP-PV 662 in ventral view; (d) interpretive drawing of MAP-PV 662 in ventral view.

adsym, adsymphyseal; an, angular; ar, articular; c1, first coronoid; c2, second coronoid; c3, third coronoid; ct, foramen for chorda tympani; d, dentary; laf, lateral angular flange; Mf, Meckelian fenestra; par, prearticular; pMf, pre-Meckelian foramina; pspl, postsplenial, sa, surangular; sfp, symphyseal fang pair of dentary; spl, splenial.

Tetrapodamorpha Ahlberg, 1991

Tanyka amnicola gen. et sp. nov.

Holotype. MAP-PV 662, nearly complete left mandible. Accessioned at Museu de Arqueologia e Paleontologia (MAP) at Universidade Federal do Piauí, Teresina, Brazil.

Type locality and horizon. Pedra de Fogo riverbank, MAP locality PB 156, south of Pastos Bons, Maranhão, lower Pedra de Fogo Formation, early Permian.

 

Etymology. Guarani: tañykã, meaning ‘jaw’ or ‘chin’, and Latin: amnicola, meaning ‘living in or next to the river’ the latter being a reference both to the river bed in Pastos Bons where the holotype was found and also to the presumed aquatic habits of the stem tetrapod.

Diagnosis. Stem tetrapod of moderate size. Adsymphyseal and all coronoids covered in a thickly ankylosed and arched denticle pad much wider than the tooth row. Occlusal surface of jaw, including coronoid denticle plate, faces more labially than dorsally when jaw is in neutral position. Ventral margin of jaw ramus wider than dentary-coronoid area. Angular with prominent sculptured flange. Prearticular braces articular medially with a large triangular process. Meckelian foramen small (less than one-third the depth of the prearticular).

Jaw rotation during mandibular adduction in Tanyka.
(a) Jaw in closed position, lateral view; (b) jaw in closed position, anterior view;
(c) jaw in open position, lateral view; (d) jaw in open position, anterior view.

General skull shape speculative, based on Baphetes

Illustration showing Tanyka amnicola in life, eating underwater plants.

 Artwork: Vitor Silva

 

Jason D. Pardo; Claudia A. Marsicano; Roger Smith; Juan Carlos Cisneros; Kenneth D. Angielczyk; Jörg Fröbisch; Christian F. Kammerer; Martha Richter. 2026. An aberrant Stem Tetrapod from the early Permian of Brazil. Proc Biol Sci. 293 (2066): 20252106. DOI: doi.org/10.1098/rspb.2025.2106 [04 Mar 2026]

  

[Paleontology • 2024] Cranial Anatomy and Phylogenetic Affinities of Bolosaurus major, with new information on the unique bolosaurid feeding apparatus and evolution of the impedance-matching ear

Bolosaurus major

in Jenkins, Foster, Napoli, Meyer, Bever et Bhullar, 2024. 

DOI: doi.org/10.1002/ar.25546 

  x.com/reptiliferous

Abstract

Resolving the phylogenetic relationships of early amniotes, in particular stem reptiles, remains a difficult problem. Three-dimensional morphological analysis of well-preserved stem-reptile specimens can reveal important anatomical data and clarify regions of phylogeny. Here, we present the first thorough description of the unusual early Permian stem reptile Bolosaurus major, including the first comprehensive description of a bolosaurid braincase. We describe previously obscured details of the palate, allowing for insight into bolosaurid feeding mechanics. Aspects of the rostrum, palate, mandible, and neurocranium suggest that B. major had a particularly strong bite. We additionally found B. major has a surprisingly slender stapes, similar to that of the middle Permian stem reptile Macroleter poezicus, which may suggest enhanced hearing abilities compared to other Paleozoic amniotes (e.g., captorhinids). We incorporated our new anatomical information into a large phylogenetic matrix (150 OTUs, 590 characters) to explore the relationship of Bolosauridae among stem reptiles. Our analyses generally recovered a paraphyletic “Parareptilia,” and found Bolosauridae to diverge after Captorhinidae + Araeoscelidia. We also included B. major within a smaller matrix (10 OTUs, 27 characters) designed to explore the interrelationships of Bolosauridae and found all species of Bolosaurus to be monophyletic. While reptile relationships still require further investigation, our phylogeny suggests repeated evolution of impedance-matching ears in Paleozoic stem reptiles.

Keywords: amniote, fossil, hearing, Paleozoic, reptile

 

Kelsey M. Jenkins, William Foster, James G. Napoli, Dalton L. Meyer, Gabriel S. Bever and Bhart-Anjan S. Bhullar. 2024. Cranial Anatomy and Phylogenetic Affinities of Bolosaurus major, with new information on the unique bolosaurid feeding apparatus and evolution of the impedance-matching ear. The Anatomical Record. DOI: doi.org/10.1002/ar.25546 

  x.com/reptiliferous/status/1817907322481426897

  x.com/AnatRecord/status/1817960743381471239

[Paleontology • 2023] Parilisthelyphonus bryantae & Inmontibusichnus charleshenryturneri • The Largest Palaeozoic Whip Scorpion and the Smallest (Arachnida: Uropygi: Thelyphonida); A New Species and A New ichnospecies from the Carboniferous of New England, USA

Parilisthelyphonus bryantae

Knecht, Benner, Dunlop & Renczkowski, 2023

DOI: 10.1093/zoolinnean/zlad088

Researchgate.net/publication/373088972

Abstract

Palaeozoic fossils of whip scorpions (Arachnida: Uropygi: Thelyphonida) are extremely rare, with only seven species of this age previously described. A new species of fossil whip scorpion, as well as the first ichnospecies assignable to this group, are described here from the Carboniferous Narragansett Basin of Massachusetts, USA. A body fossil from the Rhode Island Formation (Moscovian) is referred to as Parilisthelyphonus bryantae gen. nov., sp. nov.. At more than 34 mm long it represents both the largest known Palaeozoic whip scorpion and the first fossil arachnid found in the Rhode Island Formation in ~130 years of scrutiny. The whip scorpion trace fossil, comprising a full-body impression and associated tracks, is described from the subjacent Wamsutta Formation (Late Bashkirian) of Massachusetts, USA as Inmontibusichnus charleshenryturneri  igen. nov., isp. nov.. With an estimated body length of less than 10 mm, the producer would be the smallest known Palaeozoic thelyphonid. These discoveries within the Narragansett Basin represent only the second site in the western hemisphere, in what was western Laurasia, to yield Palaeozoic whip scorpions. The Narragansett Basin is of significant Pangaean biogeographical importance among whip scorpion sites, being located between the westernmost Mazon Creek Lagerstätte of Illinois and the eastern assemblage of localities in Europe, and serves as an important new fossil calibration point for phylogenetic studies of this arachnid group.

Keywords: Parilisthelyphonus bryantae, Inmontibusichnus charleshenryturneri, Wamsutta Formation, Rhode Island Formation, Moscovian, Bashkirian, Pennsylvanian, tracks

The holotype of Parilisthelyphonus bryantae gen. nov., sp. nov..
Part (A; MCZ:IP:198710a) and counterpart (B; MCZ:IP:198710b)

Richard J. Knecht, Jacob S. Benner, Jason A. Dunlop and Mark D. Renczkowski. 2023. The Largest Palaeozoic Whip Scorpion and the Smallest (Arachnida: Uropygi: Thelyphonida); A New Species and A New ichnospecies from the Carboniferous of New England, USA. Zoological Journal of the Linnean Society. zlad088. DOI: 10.1093/zoolinnean/zlad088

Researchgate.net/publication/373088972_The_largest_Palaeozoic_whip_scorpion_and_the_smallest_Thelyphonida_from_the_Carboniferous_of_New_England_USA

[Paleontology • 2021] Early Palaeozoic Discinocarina: A Key to the Appearance of Cephalopod Jaws

general view of the cephalic region of an orthocerid in an attacking position.
 The Aptychopsis is working as a protective shield, the dorsal plate is displaced to open the mouth with a radula on a short proboscis. The number of arms (ten) is based on Shigeno et al. 2008, 2010. The presence of well-developed eyes in orthocerids is based on the molecular study of Nautilus eyes (Ogura et al. 2013).

in Mironenko, 2021. 

DOI: 10.1111/let.12414

Reconstruction by Andrey Atuchin  deviantart.com/olorotitan

facebook.com/AleksandrMironenko90

 mirsite.ru

Abstract

Cephalopoda is the only class of molluscs in which virtually all its modern representatives have a pair of powerful jaws. There is little doubt that jaws have contributed to the evolutionary success of cephalopods, but their origin still remains a mystery. Though cephalopods appeared at the end of the Cambrian, the oldest unequivocal jaws have been reported to date from the Late Devonian, though they were initially interpreted as phyllopod crustaceans of the suborder Discinocarina. After their relation with ammonoids was proven, they were considered as opercula, and only later their mandibular nature was recognized and widely accepted. Finds of discinocarins from Silurian deposits are still considered as opercula of ammonoid ancestors - nautiloids of the order Orthocerida. However, according to modern ideas, there is no place within their soft body for the location of such large opercula. Moreover, the repeated appearance of very similar structures in the same evolutionary line at least twice, but in different places of the body and for different purposes seems highly improbable. A new hypothesis is proposed herein, in which the Silurian fossils, earlier assigned to Discinocarina, are not specialized opercula, but protective shields, to defend orthocerids not from the predators, but from their own prey. The chitinous plates around the mouth likely appeared in the Silurian orthocerids for protection from such damage and later, during Silurian and Devonian, most likely gradually evolved into the jaws.

Keywords: Anaptychi, aptychi, Aptychopsis, Cephalopoda, Discinocarina, jaw apparatus

Hypothetical reconstruction of Silurian Orthocerida with Aptychopsis as proto-jaws.
A, general view of the cephalic region of an orthocerid in an attacking position. The Aptychopsisis working as a protective shield, the dorsal plate is displaced to open the mouth with a radula on a short proboscis. The number of arms (ten) is based on Shigeno et al. 2008, 2010. The presence of well-developed eyes in orthocerids is based on the molecular study of Nautilus eyes (Ogura et al. 2013).
B, various views of Orthocerida with Aptychopsis. A small formation on the top of the orthocerid's head is an anterior part of a collar. In modern Nautilus it is a part of the protective hood (Shigeno et al. 2008), but in ancient cephalopods most likely it served to connect the head to the shell and to support collar folds (see Mironenko 2015).

(Andrey Atuchin, based on the sketch by A. A. Mironenko).

 

Aleksandr A. Mironenko. 2021. Early Palaeozoic Discinocarina: A Key to the Appearance of Cephalopod Jaws. Lethaia: an international journal of palaeontology and stratigraphy. 54(4); 457-476. DOI: 10.1111/let.12414

deviantart.com/olorotitan/art/Orthocerida-reconstruction-882845031

 facebook.com/AleksandrMironenko90/posts/1059766017761051

 mirsite.ru/papers/22.html

[Paleontology • 2021] Karutia fortunata • A New Reptile from the lower Permian of Brazil and the Interrelationships of Parareptilia

Karutia fortunata 

 Cisneros, Kammerer, Angielczyk, Fröbisch, Marsicano, Smith & Richter, 2021

 DOI: 10.1080/14772019.2020.1863487 

 facebook.com/PaleoUFPI 

  twitter.com/Synapsida 

 

Abstract

A new parareptile from the Cisuralian Pedra de Fogo Formation of north-eastern Brazil is described. Karutia fortunata gen. et sp. nov. is the first Gondwanan member of Acleistorhinidae, a clade previously known only from North America but thought to be closely related to the Russian Lanthanosuchidae. A re-examination of parareptile phylogeny indicates that lanthanosuchids are not closely related to acleistorhinids. These results are more congruent both stratigraphically and biogeographically than the previous ‘lanthanosuchoid’ position for acleistorhinids, as they eliminate a 15 Ma ghost lineage within parareptiles, leaving Acleistorhinidae as an exclusively Pennsylvanian/Cisuralian clade from western Pangaea. Karutia fortunata contributes to our knowledge of the early Permian diversity of Parareptilia in Gondwana, a clade previously represented only by the mesosaurid inhabitants of the Irati-Whitehill epicontinental sea in the southern portion of the supercontinent. The new parareptile joins captorhinids in the amniote record of the Pedra de Fogo Formation, improving our picture of the inland tetrapod fauna of the southern hemisphere during the Cisuralian.

 

Keywords: Reptilia, Parareptilia, Acleistorhinidae, Gondwana, Cisuralian, Pedra de Fogo Formation, Parnaíba Basin

 

  

 Karutia fortunata gen. et sp. nov. 

 

Juan Carlos Cisneros, Christian F. Kammerer, Kenneth D. Angielczyk, Jörg Fröbisch, Claudia Marsicano, Roger M. H. Smith and Martha Richter. 2021. A New Reptile from the lower Permian of Brazil (Karutia fortunata gen. et sp. nov.) and the Interrelationships of Parareptilia. Journal of Systematic Palaeontology.  DOI: 10.1080/14772019.2020.1863487

  facebook.com/PaleoUFPI/posts/704462156930611

  twitter.com/Synapsida/status/1349017567499870216

    

[PaleoIchthyology • 2020] Tanyrhinichthys mcallisteri • A Long-rostrumed Pennsylvanian Ray-finned Fish (Actinopterygii) and the Simultaneous Appearance of Novel Ecomorphologies in Late Palaeozoic Fishes

Tanyrhinichthys mcallisteri  Gottfried 1987

in Stack, Hodnett, Lucas & Sallan, 2020. 

DOI: 10.1093/zoolinnean/zlaa044 

penntoday.upenn.edu

 twitter.com/JackStack9

Abstract

The Carboniferous radiation of fishes was marked by the convergent appearance of then-novel but now common ecomorphologies resulting from changes in the relative proportions of traits, including elongation of the front of the skull (rostrum). The earliest ray-finned fishes (Actinopterygii) with elongate rostra are poorly known, obscuring the earliest appearances of a now widespread feature in actinopterygians. We redescribe Tanyrhinichthys mcallisteri, a long-rostrumed actinopterygian from the Upper Pennsylvanian (Missourian) of the Kinney Brick Quarry, New Mexico. Tanyrhinichthys has a lengthened rostrum bearing a sensory canal, ventrally inserted paired fins, posteriorly placed median fins unequal in size and shape, and a heterocercal caudal fin. Tanyrhinichthys shares these features with sturgeons, but lacks chondrostean synapomorphies, indicating convergence on a bottom-feeding lifestyle. Elongate rostra evolved independently in two lineages of bottom-dwelling, freshwater actinopterygians in the Late Pennsylvanian of Euramerica, as well as in at least one North American chondrichthyan (Bandringa rayi). The near-simultaneous appearance of novel ecomorphologies among multiple, distantly related lineages of actinopterygians and chondrichthyans was common during the Carboniferous radiation of fishes. This may reflect global shifts in marine and freshwater ecosystems and environments during the Carboniferous favouring such ecomorphologies, or it may have been contingent on the plasticity of early actinopterygians and chondrichthyans.

Keywords: North America, convergence, skull, vertebrate palaeontology, species redescription, Carboniferous, fish, palaeoecology, Palaeozoic, taxonomy

Figure 15. Comparison of the two broad structural forms of elongate rostra in Palaeozoic actinopterygians.
A, Tanyrhinichthys, which bears an elongate rostrum that is a lengthened snout-like structure above the mouth. B, a representative saurichthyiform (Saurichthys madagascariensis Piveteau, 1945), which bears an elongate rostrum that is a lengthened mouth (after Kogan & Romano, 2016, fig. 11B).

Jack Stack, John-Paul Hodnett, Spencer G. Lucas and Lauren Sallan. 2020. Tanyrhinichthys mcallisteri, A Long-rostrumed Pennsylvanian Ray-finned Fish (Actinopterygii) and the Simultaneous Appearance of Novel Ecomorphologies in Late Palaeozoic Fishes. Zoological Journal of the Linnean Society. zlaa044. DOI: 10.1093/zoolinnean/zlaa044

 twitter.com/JackStack9/status/1275081772988903425 

300-million-year-old fish resembles a sturgeon but took a different evolutionary path

penntoday.upenn.edu/news/300-million-year-old-fish-resembles-sturgeon-took-different-evolutionary-path

[Paleontology • 2018] Caudal Autotomy as Anti-predatory Behaviour in Palaeozoic Reptiles

Artist’s reconstruction of the Permian reptile Captorhinus with an autotomous tail (inset showing anterior caudal vertebrae with fracture planes)

in LeBlanc, MacDougall, Haridy, et al., 2018. 

 Reconstruction by Danielle Dufault.   DOI: 10.1038/s41598-018-21526-3 

Abstract

Many lizards can drop a portion of their tail in response to an attack by a predator, a behaviour known as caudal autotomy. The capacity for intravertebral autotomy among modern reptiles suggests that it evolved in the lepidosaur branch of reptilian evolution, because no such vertebral features are known in turtles or crocodilians. Here we present the first detailed evidence of the oldest known case of caudal autotomy, found only among members of the Early Permian captorhinids, a group of ancient reptiles that diversified extensively and gained a near global distribution before the end-Permian  mass extinction event of the Palaeozoic. Histological and SEM evidence show that these early reptiles were the first amniotes that could autotomize their tails, likely as an anti-predatory behaviour. As in modern iguanid lizards, smaller captorhinids were able to drop their tails as juveniles, presumably as a mechanism to evade a predator, whereas larger individuals may have gradually lost this ability. Caudal autotomy in captorhinid reptiles highlights the antiquity of this anti-predator behaviour in a small member of a terrestrial community composed predominantly of larger amphibian and synapsid predators.

Figure 1 Fracture planes in captorhinid caudal vertebrae.

 (a) Artist’s reconstruction of the Permian reptile Captorhinus with an autotomous tail (inset showing anterior caudal vertebrae with fracture planes). (b) Image and (c) SEM image of an isolated anterior caudal vertebra (ROM 73769) with a fracture plane passing through the centrum (black arrow). (d) Ventral view of an anterior, rib-bearing caudal vertebra (ROM 77410) showing the absence of any fracture plane. (e) Ventral view of a caudal vertebra bearing a fracture plane (black arrows) (ROM 73771) (f) thin-section through the sagittal plane of a caudal vertebra (ROM 73773) with a fracture plane (black arrow) passing through the ventral portion of the centrum. (g) Close-up of fracture plane (black arrows) in (f) passing into the notochordal canal.

 Abbreviations: cb, cortical bone; cct, calcified cartilage; ce, centrum; nc, neural canal; ns, neural spine; ntc, notochordal canal.
Reconstruction by Danielle Dufault. Anterior is to the left in all of the images.

A. R. H. LeBlanc, M. J. MacDougall, Y. Haridy, D. Scott and R. R. Reisz. 2018. Caudal Autotomy as Anti-predatory Behaviour in Palaeozoic Reptiles. Scientific Reports. 8, 3328.  DOI: 10.1038/s41598-018-21526-3

 twitter.com/Yara_Haridy/status/971086289918291968 art by @MesozoicMuse

Escape artist: Ancient reptile Captorhinus could detach its tail to elude predators

 utoronto.ca/news/escape-artist-ancient-reptile-captorhinus-could-detach-its-tail-elude-predators

[Paleontology • 2015] The Cranial Morphology of the Temnospondyl Australerpeton cosgriffi (Tetrapoda: Stereospondyli) from the Middle–Late Permian of Paraná Basin and the Phylogenetic Relationships of Rhinesuchidae

  Australerpeton cosgriffi in its environment (Middle–Late Permian [260 million years ago], Rio do Rasto Formation, Paraná Basin, Brazil)

Reconstruction by Rodolfo Nogueira.

DOI:  10.1111/zoj.12339 

  

Abstract

Stereospondyls are a diverse and morphologically distinctive clade of basal tetrapods that rapidly reached a global distribution and high abundance during the Early Triassic. Yet, the first stereospondyls appeared in the Middle–Late Permian of Gondwana, mostly represented by Rhinesuchidae. Australerpeton cosgriffi is a long-snouted representative of the group and one of the most complete temnospondyls known from the Permian of South America. The elements attributed to Au. cosgriffi were recovered from the Middle-Late Permian deposits of the Rio do Rasto Formation (Paraná Basin), in the Serra do Cadeado area of Brazil. Here, we review the cranial anatomy of the species, providing a comparative redescription, new anatomical data and previously unrecognized characters. Australerpeton cosgriffi is nested within Rhinesuchidae based on the anatomy of the tympanic cavity, but its long-snouted condition is unique amongst rhinesuchids. Based on the recovered information and new morphological data, the systematic position of Au. cosgriffi was assessed using a new matrix of 221 characters; of which 196 were selected from previous studies and the remaining are newly proposed. The results show Rhinesuchidae divided into Rhinesuchinae and Australerpetinae. A unique tympanic cavity formed by a well posteroventrally projected tabular horn, stapedial groove, well-developed oblique crest on the pterygoid, and a dorsal pterygoid crest (new term) characterizes the ear region of Rhinesuchidae. Australerpeton cosgriffi is the only undisputed Rhinesuchidae record outside southern Africa and the first long-snouted Stereospondyli, and thus is useful in helping to understand the diversification of the stereospondyls during the Middle/Late Permian of Gondwana.

Keywords: Gondwana; long-snouted rhinesuchid; Palaeozoic; phylogenetics; Rio do Rasto Formation; systematics; Temnospondyli; tympanic cavity

Estevan Eltink, Eliseu V. Dias, Sérgio Dias-da-Silva, Cesar L. Schultz and Max C. Langer. 2015. The Cranial Morphology of the Temnospondyl Australerpeton cosgriffi (Tetrapoda: Stereospondyli) from the Middle–Late Permian of Paraná Basin and the Phylogenetic Relationships of Rhinesuchidae.  Zoological Journal of the Linnean Society. 176(4);   835–860.  DOI: 10.1111/zoj.12339

ResearchGate.net/publication/282870755_The_cranial_morphology_of_the_temnospondyl_Australerpeton_cosgriffi_Tetrapoda_Stereospondyli_from_the_Middle-Late_Permian_of_Parana_Basin_and_the_phylogenetic_relationships_of_Rhinesuchidae

Paleontologists describe giant amphibian that lived 260 million years ago http://agencia.fapesp.br/paleontologists_describe_giant_amphibian_that_lived_260_million_years_ago/22285/

[Paleontology • 2016] Aquilonifer spinosus • Tiny Iindividuals attached to A New Silurian Arthropod from Herefordshire Lagerstätte of England, Suggest A Unique Mode of Brood Care

Aquilonifer spinosus 

Briggs, Siveter, Siveter, Sutton & Legg, 2016  

  DOI:  10.1073/pnas.1600489113 

Significance

The paper reports a remarkable arthropod from the Silurian Herefordshire Lagerstätte of England. The fossil reveals a unique association in an early Paleozoic arthropod involving tethering of 10 tiny individuals each by a single thread to the tergites so that their appearance is reminiscent of kites. The evidence suggests that these are juveniles and that the specimen records a unique brooding strategy. This is part of a diversity of complex brooding behaviors in early arthropods heralding the variety that occurs today. The possibility that the small individuals represent a different arthropod, possibly parasitic, which colonized the larger individual, seems less likely.

Abstract

The ∼430-My-old Herefordshire, United Kingdom, Lagerstätte has yielded a diversity of remarkably preserved invertebrates, many of which provide fundamental insights into the evolutionary history and ecology of particular taxa. Here we report a new arthropod with 10 tiny arthropods tethered to its tergites by long individual threads. The head of the host, which is covered by a shield that projects anteriorly, bears a long stout uniramous antenna and a chelate limb followed by two biramous appendages. The trunk comprises 11 segments, all bearing limbs and covered by tergites with long slender lateral spines. A short telson bears long parallel cerci. Our phylogenetic analysis resolves the new arthropod as a stem-group mandibulate. The evidence suggests that the tethered individuals are juveniles and the association represents a complex brooding behavior. Alternative possibilities—that the tethered individuals represent a different epizoic or parasitic arthropod—appear less likely.

Keywords: Arthropod; Silurian; brood care; juvenile; Herefordshire Lagerstätte

Aquilonifer spinosus is a new genus and species of arthropod from the Herefordshire Lagerstätte, a late Wenlock (mid-Silurian) volcaniclastic deposit in Herefordshire, United Kingdom. It is preserved, as are the other fossils from this Lagerstätte, in three dimensions as a calcitic void fill in a carbonate concretion. The name of the new taxon refers to the fancied resemblance between the tethered individuals and kites, and echoes the title of the 2003 novel The Kite Runner by Khaled Hosseini (aquila, eagle or kite; -fer, suffix meaning carry; thus aquilonifer, kite bearer; spinosus, spiny, referring to the long lateral spines on the tergites). The material is a single specimen, the holotype OUMNH C.29695, registered at the Oxford University Museum of Natural History (Fig. 1 and Movie S1).

Diagnosis. Features include a head shield with rostrum-like anterior projection, large uniramous antenna, chelate limb, and two other biramous appendages in the head, the last similar to those of the trunk; an elongated trunk with long, slender lateral spines on the 11 tergites, with all trunk somites bearing limbs of which all but the last are biramous; and a short telson and long cerci.

......

Derek E. G. Briggs, Derek J. Siveter, David J. Siveter, Mark D. Sutton and David Legg. 2016. Tiny Iindividuals attached to A New Silurian Arthropod Suggest A Unique Mode of Brood Care.
Proceedings of the National Academy of Sciences. 113(16) DOI:  10.1073/pnas.1600489113

[Paleontology • 2012] Siphusauctum gregarium • A New Stalked Filter-Feeder from the Middle Cambrian Burgess Shale, British Columbia, Canada

Abstract 

Burgess Shale-type deposits provide invaluable insights into the early evolution of body plans and the ecological structure of Cambrian communities, but a number of species, continue to defy phylogenetic interpretations. Here we extend this list to include a new soft-bodied animal, Siphusauctum gregarium n. gen. and n. sp., from the Tulip Beds (Campsite Cliff Shale Member, Burgess Shale Formation) of Mount Stephen (Yoho National Park, British Columbia). With 1,133 specimens collected, S. gregarium is clearly the most abundant animal from this locality.

This stalked animal (reaching at least 20 cm in length), has a large ovoid calyx connected to a narrow bilayered stem and a small flattened or bulb-like holdfast. The calyx is enclosed by a flexible sheath with six small openings at the base, and a central terminal anus near the top encircled by indistinct openings. A prominent organ, represented by six radially symmetrical segments with comb-like elements, surrounds an internal body cavity with a large stomach, conical median gut and straight intestine. Siphusauctum gregarium was probably an active filter-feeder, with water passing through the calyx openings, capturing food particles with its comb-like elements. It often occurs in large assemblages on single bedding planes suggesting a gregarious lifestyle, with the animal living in high tier clusters. These were probably buried en masse more or less in-situ by rapid mud flow events.

Siphusauctum gregarium resembles Dinomischus, another Cambrian enigmatic stalked animal. Principal points of comparison include a long stem with a calyx containing a visceral mass and bract-like elements, and a similar lifestyle albeit occupying different tiering levels. The presence in both animals of a digestive tract with a potential stomach and anus suggest a grade of organization within bilaterians, but relationships with extant phyla are not straightforward. Thus, the broader affinities of S. gregarium remain largely unconstrained.

The filter-feeder Siphusauctum lived 500 million years ago in clusters on the sea floor. CREDIT: © Royal Ontario Museum 

Lorna J. O'Brien & Jean-Bernard Caron 2012. A new stalked filter-feeder from the Middle Cambrian Burgess Shale, British Columbia, Canada. PLoS ONE 7 (1): e29233.

http://dx.doi.org/10.1371/journal.pone.0029233

http://palaeoblog.blogspot.com/2012/01/siphusauctum-gregarium-from-burgess.html

http://www.livescience.com/18003-tulip-animal-fossil.html