[Paleontology • 2025] Cheilophis periplanetes • Another Wanderer from the Paleocene-Eocene Thermal Maximum? A New Species of the North American Snake Genus Cheilophis Gilmore, 1938 (Serpentes: Constrictores) from the early Eocene of France

Cheilophis periplanetes

Georgalis & Mennecart, 2025

  sciencepress.MNHN.fr 

We here document new snake vertebral material from the early Eocene (MP 10) of Cuis, France, that we describe as a new species of Cheilophis Gilmore, 1938, a genus that was so far exclusively known from the Paleocene and Eocene of North America. The new taxon bears several anatomical features with the type, and so far, only known species of Cheilophis from North America. However, there are also important differences that allow us to recognize it as a new congeneric species. If our identification is correct, this first observed occurrence of Cheilophis from France adds another shared terrestrial vertebrate genus between Europe and North America, reinforcing biogeographic hypotheses about dispersals between the two landmasses around the Paleocene-Eocene Thermal Maximum (PETM).

Keywords: Serpentes, vertebral morphology, dispersals, Paleogene, new species

SERPENTES Linnaeus, 1758

ALETHINOPHIDIA Nopcsa, 1923

CONSTRICTORES Oppel, 1811 (sensu Georgalis &Smith, 2020)

Cheilophis periplanetes n. sp.

Etymology. The new species epithet is from the greek word 'periplanetes', which means “wanderer”, reflecting the potential wandering that occurred during the dispersals among North America and Europe.

 

Georgios L. GEORGALIS and Bastien MENNECART. 2025. Another Wanderer from the Paleocene-Eocene Thermal Maximum? A New Species of the North American Snake Genus Cheilophis Gilmore, 1938 from the early Eocene of France. Comptes Rendus Palevol. 24 (16) 317-331. DOI: doi.org/10.5852/cr-palevol2025v24a16 [25 June 2025]

  sciencepress.MNHN.fr/en/periodiques/comptes-rendus-palevol/24/16

This article is a part of the thematic issue: Snakes from the Cenozoic of Europe – towards a macroevolutionary and palaeobiogeographic synthesis.

https://x.com/DrGeorgalis/status/1937876893199478842

[PaleoOrnithology • 2024] Paakniwatavis grandei • A new Paleogene fossil and a new dataset for Waterfowl (Aves: Anseriformes) clarify phylogeny, ecological evolution, and Avian Evolution at the K-Pg Boundary

Paakniwatavis grandei 

Musser & Clarke, 2024 

DOI: doi.org/10.1371/journal.pone.0278737

Abstract

Despite making up one of the most ecologically diverse groups of living birds, comprising soaring, diving and giant flightless taxa, the evolutionary relationships and ecological evolution of Anseriformes (waterfowl) remain unresolved. Although Anseriformes have a comparatively rich, global Cretaceous and Paleogene fossil record, morphological datasets for this group that include extinct taxa report conflicting relationships for all known extinct taxa. Correct placement of extinct taxa is necessary to understand whether ancestral anseriform feeding ecology was more terrestrial or one of a set of diverse aquatic ecologies and to better understand avian evolution around the K-T boundary. Here, we present a new morphological dataset for Anseriformes that includes more extant and extinct taxa than any previous anseriform-focused dataset and describe a new anseriform species from the early Eocene Green River Formation of North America. The new taxon has a mediolaterally narrow bill which is rarely found in previously described anseriform fossils. The matrix created to assess the placement of this taxon comprises 41 taxa and 719 discrete morphological characters describing skeletal morphology, musculature, syringeal morphology, ecology, and behavior. We additionally combine the morphological dataset with published sequences using Bayesian methods and perform ancestral state reconstruction for select morphological, ecological and behavioral characters. We recover the new Eocene taxon as the sister taxon to (Anseranatidae+Anatidae) across all analyses, and find that the new taxon represents a novel ecology within known Anseriformes and the Green River taxa. Results provide insight into avian evolution during and following the K-Pg mass extinction and indicate that Anseriformes were likely ancestrally aquatic herbivores with rhamphothecal lamellae..

Photograph (A) and line drawing (B) of the holotype specimen of Paakniwatavis grandei (FMNH PA725). Bone is unfilled. Extremely crushed bone and bone margin is delimited with dashed margins.

Anatomical abbreviations: prx, premaxilla; max, maxilla; jug, jugal; orb, orbital margin; rmf, rostral mandibular fenestra; scl, scleral ossicles; mnd, mandible; rde, radiale; cmc, carpometacarpus.

Photograph (A) and line drawing (B) of the holotype specimen of Paakniwatavis grandei (FMNH PA725). Extremely crushed bone and bone margin is delimited with dashed margins.

Anatomical abbreviations: prx, premaxilla; orb, orbital margin; mnd, mandible; cvt, cervical vertebrae; tvt, thoracic vertebrae; syn, synsacrum; pyg, pygostyle; cor, coracoid; scp, scapula; fur, furcula; str, sternum; rbs, ribs; hum, humerus; uln, ulna; rad, radius; rde, radiale; cmc, carpometacarpus; mII:1, phalanx 1 of manual digit II; mtII:2, phalanx 2 of manual digit II; ili, ilium; fem, femur; tbt, tibiotarsus; tmt, tarsometatarsus; mtI, metatarsal I; I:1, phalanx 1 of pedal digit I; II:1, phalanx 1 of pedal digit II; III:1, phalanx 1 of pedal digit III; IV:1, phalanx 1 of pedal digit IV.

Systematic paleontology

AVES Linnaeus, 1758 

NEOGNATHAE Pycraft, 1900 

ANSERIFORMES Wagler, 1831 

Paakniwatavis grandei, gen. et sp. nov.

Etymology: Paakniwatavis references Paakniwat, used by the Shoshoni tribe indigenous to the region of the recovery site and means “Water Spirit”. The Water Spirits are dangerous supernatural beings that lure people to their death with child-like cries. The name references the aquatic ecology of this taxon. The species honors Dr. Lance Grande, who collected the holotype specimen, in recognition of his leading research on the faunas of the Green River Formation.

 Grace Musser and Julia A. Clarke. 2024. A new Paleogene fossil and a new dataset for waterfowl (Aves: Anseriformes) clarify phylogeny, ecological evolution, and avian evolution at the K-Pg Boundary. PLoS ONE. 19(7): e0278737. DOI: doi.org/10.1371/journal.pone.0278737

https://www.biorxiv.org/content/10.1101/2022.11.23.517648v1.full

[PaleoOrnithology • 2023] Anachronornis anhimops • Basal Anseriformes from the Early Paleogene of North America and Europe

 Anachronornis anhimops 

Houde, Dickson & Camarena, 2023 

   

 DOI:  10.3390/d15020233  

Abstract

We describe nearly complete skeletons of basal Anseriformes from the Latest Paleocene to the early Eocene of North America and Europe. Collectively, these birds appear to be representative of anseriforms near the divergence of Anhimae and Anseres, but their exact positions relative to these clades remains uncertain. A new family, Anachronornithidae nov. fam., is erected on the basis of one of these, Anachronornis anhimops nov. gen., nov. gen. et sp., to which the others cannot be confidently assigned. The new fossils augment a growing collection of early Pan-Anseriformes, which in their diversity do not paint an unambiguous picture of phylogeny or character state evolution on the path to or within crown-Anseriformes. Anachronornis nov. gen. is similar in some aspects of both cranial and postcranial anatomy to other well-represented early Paleogene Anseriformes and members of Anseres, such as Presbyornis Wetmore, 1926. However, it exhibits a more landfowl-like bill, like that of Anhimae and unlike the spatulate bill of Anseres. Additional specimens of similar basal Anseriformes of uncertain affinities from the early Eocene of North America and Europe further complicate interpretation of character state polarity due to the mosaicism of primitive and derived characters they exhibit.  

Keywords: Anseriformes; Anseres; Anhimidae; Anachronornithidae; Presbyornis; Anatalavis; Nettapterornis; Anachronornis; Danielsavis

 

  Holotype of Anachronornis anhimops nov. gen. et sp. (USNM 496700):
skull, ventral (A), dorsal (B), right lateral (C), right lateral in matrix (D), caudal (E); mandible with heavy gauge wire glued to medial side of right dentary, right lateral (F), dorsal (G), oblique caudomedial aspect of right side (K), right caudal (O); quadrates, left lateral (H), right lateral (I), left medial (L), right medial (M); basihyal (Q), costal fragment with uncinate process (R), left palatine (S), right thoracic vertebrae (T). Quadrate (USNM 496701; Anseriformes fam. incertae sedis): right lateral (J), right medial (N).
Holotype of Danielsavis nazensis nov. gen. et sp. (NMS.Z.2021.40.1): right caudal mandible (P).

All but (D,P) are coated with ammonium hydroxide. Scale bar 1 cm.

 Class Aves Linnaeus, 1758

Order Anseriformes Wagler, 1831

Family Anachronornithidae nov. fam. Houde, Dickson, and Camarena

 

Included genus Anachronornis nov. gen.

Diagnosis: Anachronornithidae nov. fam. is distinguished from all known Anhimidae and Anseres by a lack of unambiguous synapomorphies diagnosing those respective clades and in many respects is intermediate between the two.

Anachronornis nov. gen. Houde, Dickson, and Camarena

 

Etymology: From the Greek ἀναχρονισμός, out of time, and ὄρνις, bird, alluding to the unexpectedly late occurrence of what may be, or may be close to, the most recent common ancestor of the two crown-anseriform lineages, Anhimae and Anseres.

Type and only known species: Anachronornis anhimops nov. gen. et sp.

Occurrence: Late Paleocene of North America.

Diagnosis: As for the family, by monotypy. (Full account of all putative apomorphies by dataset in Supplemental Materials and Supplementary Appendices A3, B2, C2, D2, F3, G6 and G7).

Anachronornis anhimops nov. gen. et sp. Houde, Dickson, and Camarena

Etymology: From the generic name Anhima, a screamer, and ops (Greek, face, countenance, appearance of the face). The name is intended to refer to the screamer-like bill and appearance of the head, particularly like that of Anhima in which the supraorbital region may be somewhat narrower than in Chauna.

 Peter Houde, Meig Dickson and Dakota Camarena. 2023. Basal Anseriformes from the Early Paleogene of North America and Europe. Diversity. 15(2); 233. DOI:  10.3390/d15020233  

 

  

[PaleoMammalogy • 2024] Parutaetus oliveirai • Revealing the Diversity of Paleogene Cingulates from Brazil: A New Species of Parutaetus (Cingulata: Chlamyphoridae: Euphractinae) in the Guabirotuba Formation (middle–late Eocene)

Parutaetus oliveirai

 Klimeck, Ciancio, Sedor & Kerber, 2024

 DOI: doi.org/10.1080/02724634.2024.2403581  

  Researchgate.net/publication/384656990

 x.com/KerberLeonardo

Art by Márcio L. Castro.

ABSTRACT

Parutaetus is an early-diverging Euphractinae cingulate that inhabited South America during the middle Eocene–early Oligocene. Four species are known: P. chicoensis, P. clusus, P. chilensis, and P. punaensis. Here, we describe a new species of this genus from Guabirotuba Formation (middle-upper Eocene of Brazil). The osteoderms differ from other species of the genus by presenting: (i) more surface glandular and piliferous foramina; (ii) the articulation surface of the area between the osteoderms is flat and full of pronounced, round, and anastomosed projections forming serrated external and medial edges with a median projection (indentations); and (iii) larger size than other species of the genus. In combination, this suite of traits is not present in other species of the genus. The increase in the number of surface glandular and piliferous foramina may be associated with the global cooling that occurred during the middle–late Eocene that affected the South American fauna. Finally, the new species expands the knowledge about the diversity of taxa that inhabited southeast South America during the Paleogene.

External views of the fixed osteoderms of Parutaetus oliveirai.

 Hypothetical artistic reconstruction of Parutaetus oliveirai in the middle-late Eocene of Brazil.

Art by Márcio L. Castro.

 Parutaetus oliveirai

Tabata D. F. Klimeck, Martín R. Ciancio, Fernando A. Sedor and Leonardo Kerber. 2024. Revealing the Diversity of Paleogene Cingulates from Brazil: A New Species of Parutaetus (Euphractinae) in the Guabirotuba Formation (middle–late Eocene). Journal of Vertebrate Paleontology. 44(1);  e2403581. DOI: doi.org/10.1080/02724634.2024.2403581  

  Researchgate.net/publication/384656990_Revealing_the_diversity_of_Paleogene_cingulates_from_Brazil_a_new_species_of_Parutaetus_in_the_Guabirotuba_Formation

 x.com/KerberLeonardo/status/1844710941260173615

[PaleoEntomology • 2024] Palaeorhoptrocentrus tenuicornis, Taphaeus obscurus & Eubazus electrus • New Species of braconid parasitoid wasps from the Subfamilies Doryctinae and Brachistinae (Hymenoptera: Braconidae) from late Eocene Baltic Amber

 

Belokobylskij, Pankowski & Zaldívar-Riverón, 2024 

DOI: 10.11646/palaeoentomology.7.5.8

Abstract

Three new fossil species of braconid wasps are described and illustrated from late Eocene Baltic amber: Palaeorhoptrocentrus tenuicornis sp. nov. (Doryctinae), Taphaeus obscurus sp. nov. (Brachistinae: Diospilini), and Eubazus electrus sp. nov. (Brachistinae: Brachistini). Keys to the known species of Palaeorhoptrocentrus Belokobylskij, 2023 and to species of Eubazus Nees, 1812 described from Baltic amber are provided. An illustrated redescription of Blacus (Electroblacus) facialis Brues, 1933 (Brachistinae: Blacini) is also provided, along with digital photographs for the first time of the female of B. (Electroblacus) facialis, whose type material was lost during the World War II. We also provide morphological notes and digital photographs of a male belonging to an undescribed species of Meteorus (Euphorinae).

Eocene, parasitoids, wasp, fossil, Diospilini, Blacini, Brachistini, Meteorus

 

Sergey A. Belokobylskij, Madeline V. Pankowski, Alejandro Zaldívar-Riverón. 2024. New Species of braconid parasitoid wasps from the Subfamilies Doryctinae and Brachistinae from late Eocene Baltic Amber.  Palaeoentomology. 7(5); 645–658. DOI: doi.org/10.11646/palaeoentomology.7.5.8

 x.com/ZaldivarRiveron/status/1851562765980229755 

[PaleoEntomology • 2019] Danatettix hoffeinsorum • The Last batrachideine of Europe: A New Genus and Species of Pygmy Grasshopper (Orthoptera: Tetrigidae) from Eocene Baltic Amber

Danatettix hoffeinsorum

 Thomas, Skejo & Heads, 2019

 

DOI: 10.11646/zootaxa.4686.3.9

Abstract

A new genus and species of pygmy grasshopper (Orthoptera: Tetrigidae) is described from Eocene Baltic amber. Danatettix hoffeinsorum gen. et sp. nov. is assigned to the subfamily Batrachideinae based on antennae with more than 19 antennomeres, sulcate mesofemora, and rectangular paranota. This species is readily distinguished from other batrachideines by a markedly produced vertex, pronotum with divergent internal and external lateral carinae, and highly setiferous female lateral basivalvular sclerite with scabrose integument. The morphology of Danatettix suggests placement within the here defined Tettigidea genus group (comprising Eutettigidea Hancock, 1914, Paurotarsus Hancock, 1900, and Tettigidea Scudder, 1862) and suggests that the latter had diverged from the new Scaria genus group (comprising Eotetrix Gorochov, 2012, Rehnidium Grant, 1956 and Scaria Bolívar, 1887) by the Early Eocene.

Keywords: Orthoptera, Caelifera, Tetrigoidea, pygmy locusts, grouse locusts, groundhoppers, Cenozoic, Paleogene, Baltic amber, fossil insects

 Danatettix hoffeinsorum [holotype 1084-4]
 Dorsal oblique view;  Line drawing.

 (scale bar = 1 mm)

  

Danatettix hoffeinsorum gen. et sp. nov. 

 Danatettix hoffeinsorum
Fig 3. Ventral view of holotype 1084-4 (scale bar = 1 mm).
Fig 4. Close-up ventral view of ovipositor valvulae and subgenital plate of holotype 1084-4 (scale bar = 0.2 mm)

M. Jared Thomas, Josip Skejo and Sam W. Heads. 2019. The Last batrachideine of Europe: A New Genus and Species of Pygmy Grasshopper (Orthoptera: Tetrigidae) from Eocene Baltic Amber. Zootaxa. 4686(3); 435–445. DOI: 10.11646/zootaxa.4686.3.9

[Entomology • 2022] Paleogene Forest Fragmentation and Out-of-Africa Dispersal explain Radiation of the Paleotropical Dung Beetle tribe Epactoidini trib. nov. (Coleoptera: Scarabaeidae: Scarabaeinae)

Species illustrated: (a) Ochicanthon hanskii Krikken & Huijbregts, (b) O. woroae Ochi, Ueda & Kon, (c) O. crypticus Krikken & Huijbregts, (d) O. devagiriensis Sabu & Latha, (e) O. ceylonicus Cuccodoro, (f) Grebennikovius basilewskyi (Balthasar), (g) Epactoides giganteus, (h) E. madecassus (Paulian), (i) E. major (Paulian), (j) E. frontalis (Montreuil).

 Epactoidini trib. nov.

Rossini, Grebennikov, Merrien, Miraldo, Viljanen & Tarasov, 2022

DOI: 10.1111/syen.12564 

 twitter.com/Tarasov_Sergio

Abstract

Paleotropical clades with largely disjunct distributions are ideal models for biogeographic reconstructions. The dung beetle genera Grebennikovius Mlambo, Scholtz & Deschodt, Epactoides Olsouffief and Ochicanthon Vaz-de-Mello are distributed in Tanzania, Madagascar and Réunion, and the Oriental region, respectively. We combine morphology and molecular dataset to reconstruct the phylogenetic relationships between these taxa. Our analyses corroborate previous hypotheses of monophyly of the group, which is here described as new tribe Epactoidini trib. nov. Grebennikovius is recovered as sister to Epactoides, while Ochicanthon emerges as sister to them both. The disjunct distribution of our focal clade is unusual within the subfamily Scarabaeinae. Bayesian divergence time estimates and ancestral range reconstructions indicate an African origin of the crown group of the tribe Epactoidini trib. nov. in the early mid Eocene, ca. 46 Ma. The divergence between Epactoides and its sister is dated to 32.3 Ma, while the crown age for the genus Ochicanthon is dated to 27 Ma. We investigate the factors that may have shaped the current distribution of the tribe Epactoidini trib. nov. The formation of the Gomphotherium landbridge, along with favourable environmental conditions would have allowed dry-intolerant organisms, such as Ochicanthon, to disperse out of Africa. Remarkable climatic stability of the Eastern Arc Mountains was critical for the retention of the monotypic genus Grebennikovius. We suggest two subsequent overwater dispersal events: the migration of the most recent common ancestor (MRCA) of Epactoides from Africa to Madagascar (32.3–29.5 Ma); the lately dispersal of the MRCA of the today's extinct Epactoides giganteus Rossini, Vaz-de-Mello & Montreuil to Réunion island from Madagascar (3.4 Ma). We suggest that the high potential of dispersal of Epactoidini trib. nov. dung beetles and the strict association to forest habitat might have triggered two major radiations, one in Madagascar and one in the Oriental Region.

Keywords: biogeography, evolution, phylogenetics

Epactoidini trib. nov. 

Type genus: Epactoides Olsouffief, 1947

Genera: Epactoides Olsouffief, 1947

Grebennikovius Mlambo et al., 2019

Ochicanthon Vaz-de-Mello, 2003.

Distribution: Tanzania (Uluguru Mountains); Madagascar; Réunion Island; Oriental Region: from southern India to southern Philippines. 

Diagnosis: The tribe Epactoidini is supported by the following diagnostic characters (Figure 2): (i) elytra with 9–10 striae; (ii) besides epipleural carina, elytra with one or two additional lateral carinas; (iii) endophallus without frontolateral peripheral (FLP) endophallite; (iv) radial posterior (RP1) sclerite of hindwings (when present) approaches the posterior side the radial anterior (RA4) sclerite.

Ancestral range reconstruction of Epactoidini trib. nov. BioGeoBEAR tree and map showing suggested dispersal routes of Epactoides and Ochicanthon from Afrotropical ancestors, including date estimation. Nodal support values are expressed as UFBS and SH-aLRT. Bars at nodes indicate 95% CI of estimated ages. Distribution areas of Epactoidini members: Eastern Arc Mountains (EAMs) (red); Madagascar (light blue); Réunion (purple); Oriental (green).
Species illustrated: (a) Ochicanthon hanskii Krikken & Huijbregts, (b) O. woroae Ochi, Ueda & Kon, (c) O. crypticus Krikken & Huijbregts, (d) O. devagiriensis Sabu & Latha, (e) O. ceylonicus Cuccodoro, (f) Grebennikovius basilewskyi (Balthasar), (g) Epactoides giganteus, (h) E. madecassus (Paulian), (i) E. major (Paulian), (j) E. frontalis (Montreuil).

   

Michele Rossini, Vasily Grebennikov, Thomas Merrien, Andreia Miraldo, Heidi Viljanen and Sergei Tarasov. 2022. Paleogene Forest Fragmentation and Out-of-Africa Dispersal explain Radiation of the Paleotropical Dung Beetle tribe Epactoidini trib. nov. (Coleoptera: Scarabaeinae). Systematic Entomology. DOI: 10.1111/syen.12564

  twitter.com/Tarasov_Sergio/status/1569318421250117637

[PaleoMammalogy • 2023] Ashaninkacebus simpsoni • An eosimiid Primate (Eosimiiformes) of South Asian Affinities in the Paleogene of Western Amazonia and the Origin of New World Monkeys

Ashaninkacebus simpsoni

Marivaux, Negri, Antoine, Stutz, Condamine, Kerber, Pujos, Santos, Alvim, Hsiou, Bissaro, Adami-Rodrigues & Ribeiro, 2023

DOI: 10.1073/pnas.2301338120

Abstract

Recent fossil discoveries in Western Amazonia revealed that two distinct anthropoid primate clades of African origin colonized South America near the Eocene/Oligocene transition (ca. 34 Ma). Here, we describe a diminutive fossil primate from Brazilian Amazonia and suggest that, surprisingly, a third clade of anthropoids was involved in the Paleogene colonization of South America by primates. This new taxon, Ashaninkacebus simpsoni gen. et sp. nov., has strong dental affinities with Asian African stem anthropoids: the Eosimiiformes. Morphology-based phylogenetic analyses of early Old World anthropoids and extinct and extant New World monkeys (platyrrhines) support relationships of both Ashaninkacebus and Amamria (late middle Eocene, North Africa) to the South Asian Eosimiidae. Afro-Arabia, then a mega island, played the role of a biogeographic stopover between South Asia and South America for anthropoid primates and hystricognathous rodents. The earliest primates from South America bear little adaptive resemblance to later Oligocene-early Miocene platyrrhine monkeys, and the scarcity of available paleontological data precludes elucidating firmly their affinities with or within Platyrrhini. Nonetheless, these data shed light on some of their life history traits, revealing a particularly small body size and a diet consisting primarily of insects and possibly fruit, which would have increased their chances of survival on a natural floating island during this extraordinary over-water trip to South America from Africa. Divergence-time estimates between Old and New World taxa indicate that the transatlantic dispersal(s) could source in the intense flooding events associated with the late middle Eocene climatic optimum (ca. 40.5 Ma) in Western Africa.

Keywords: Brazilian Amazonia; Platyrrhini; paleobiogeography; phylogeny; teeth.

 Ashaninkacebus simpsoni gen. et sp. nov.

Significance: 

Western Amazonia has recently revealed that two distinct anthropoid primate clades of African origin colonized South America near the Eocene/Oligocene transition (ca. 34 Ma). Here, we report a new fossil primate from Brazilian Amazonia pointing to a third clade involved in that colonization. Surprisingly, this taxon has strong affinities with eosimiid anthropoids of South Asian origin. These data highlight some of the life history traits (very-small-bodied size and insectivory/frugivory) that would have increased the chances of survival on a natural raft during this extraordinary transatlantic journey from Africa to South America. Estimated splits between New and Old World taxa indicate that the dispersal(s) coincides with the late middle Eocene climatic optimum (ca. 40.5 Ma), which generated intense flooding events.

Laurent Marivaux, Francisco R. Negri, Pierre-Olivier Antoine, Narla S Stutz, Fabien L. Condamine, Leonardo Kerber, François Pujos, Roberto Ventura Santos, André M. V. Alvim, Annie S. Hsiou, Marcos C. Bissaro Jr., Karen Adami-Rodrigues and Ana Maria Ribeiro. 2023. An eosimiid Primate of South Asian Affinities in the Paleogene of Western Amazonia and the Origin of New World Monkeys. Proc Natl Acad Sci USA. 120 (28) e2301338120. DOI: 10.1073/pnas.2301338120

[PaleoMammalogy • 2023] A Macroevolutionary Pathway to Megaherbivory

in Sanisidro, Mihlbachler & Cantalapiedra, 2023.

 DOI: 10.1126/science.ade1833 

 twitter.com/Canta_Lab

Abstract

Several scenarios have been proposed to explain rapid net size increases in some early Cenozoic mammalian lineages: sustained and gradual directional change, successive occupation of adaptive zones associated with progressively larger body sizes, and nondirectional evolution associated with branching events in combination with higher diversification potential of the larger lineages. We test these hypotheses in brontotheres, which are among the first radiations of mammals that consistently evolved multitonne sizes. Body-mass evolution in brontotheres mainly occurred during speciation and had no preferential direction. Long-term directional change stemmed from the higher survival of larger lineages in less-saturated herbivore guilds. Our study emphasizes the role of differential species proliferation in explaining the long-term phenotypic trends observed in the fossil record, which are more than an accumulation of steady microevolutionary changes.

Editor’s summary: 

After the extinction of large dinosaurs at the end of the Cretaceous, many mammals underwent a rapid increase in size. Several hypotheses for this change have been put forward, with much debate about the drivers. Sanisidro et al. looked at the record of body size in brontotheres, large herbivorous mammals from the Eocene that experienced orders of magnitude changes in size. The authors saw no evidence for directional selection, but instead found a pattern of increased survival of larger species caused by reduced competition with other herbivores in their niches. Thus, over time, the increase in body size in these mammals was caused by the macroevolutionary process of species sorting. —Sacha Vignieri

Oscar Sanisidro, Matthew C Mihlbachler and Juan L Cantalapiedra. 2023. A Macroevolutionary Pathway to Megaherbivory. SCIENCE. 380, 6645; 616-618. DOI: 10.1126/science.ade1833

  twitter.com/Canta_Lab/status/1656720984617934850

  phys.org/news/2023-05-differential-species-proliferation-key-evolutionary.html

[Paleontology • 2023] Taubaracna maculosa • First Fossil Spider from Paleogene in South America

 Taubaracna maculosa

Martine, Mesquita, Carvalho, Beloto, Ricardi-Branco & Garcia, 2023

DOI: 10.1016/j.jsames.2022.104147

 twitter.com/PaleoCisneros 

 Abstract

Spiders (Order Araneae) can be found in all continents, except Antarctica. This order has a long evolutionary history that began during the Paleozoic Era. Despite this prolonged span and the diversity of extant species, the fossil record of spiders is relatively modest, with most specimens preserved in amber and found in the Northern Hemisphere. Taubaracna maculosa nov. gen. et sp., preserved in Oligocene sediments from the Tremembé Formation, Taubaté Basin, Brazil, is described here based on a single medium-sized fossil that presents elongated legs with bristles and spines and a reduced prosoma and opisthosoma. Unusually, the specimen presents a banding pattern (light and dark pigments) still preserved on the exoskeleton, suggesting a camouflage pattern common to many extant spider species.

 Taubaracna maculosa nov. gen. et sp.

Ariel Milani Martine, Marisa Vianna Mesquita, Ighor Carvalho, Beatriz Beloto, Fresia Ricardi-Branco and Maria Judite Garcia. 2023. Taubaracna maculosa: First Fossil Spider from Paleogene in South America. Journal of South American Earth Sciences. 121, 104147. DOI: 10.1016/j.jsames.2022.104147

 twitter.com/PaleoCisneros/status/1616217571480551424

[PaleoMammalogy • 2021] Eusmilus adelos • The Largest Hoplophonine (Carnivora: Nimravidae) and A Complex New Hypothesis of Nimravid Evolution

Eusmilus adelos

 Barrett, 2021

DOI: 10.1038/s41598-021-00521-1 

twitter.com/nimravenous 

skeletal reconstruction by Dhruv Franklin  twitter.com/DhruvFranklin

Abstract

Nimravids were the first carnivorans to evolve saberteeth, but previously portrayed as having a narrow evolutionary trajectory of increasing degrees of sabertooth specialization. Here I present a novel hypothesis about the evolution of this group, including a description of Eusmilus adelos, the largest known hoplophonine, which forces a re-evaluation of not only their relationships, but perceived paleoecology. Using a tip-dated Bayesian analysis with sophisticated evolutionary models, nimravids can now be viewed as following two paths of evolution: one led to numerous early dirk-tooth forms, including E. adelos, while the other converged on living feline morphology, tens of millions of years before its appearance in felids.

Partial skeleton of USNM 12820, Eusmilus adelos with shaded known elements. Cranial abbreviations: fr frontal, na nasal, mp mastoid process, (A) cn carnassial notch, mc main cusp of P3, pa paracone, pcc posterior cingular cusp of P3, ps parastyle; (B–D) bis brachialis insertion site, lg lateral groove of ulna, rn radial notch, sln semilunar notch, (E–G) ce capitular eminence of radius, rt radial tuberosity, (H–J) dpc delto-pectoral crest, of olecranon fossa, sc supinator crest (brachial flange), *remnants of bridge enclosing epicondylar foramen. Eusmilus adelos skeletal reconstruction by Dhruv Franklin.

Tip-dated Bayesian phylogeny of the Nimravidae, outgroups (save Tapocyon) removed. Two main clades were recovered, the Hopliphoninae and Nimravinae, the latter of which includes all barbourofelin taxa. Color gradient reflects maximum-likelihood estimation of ancestral body mass. Additional nodal values (e.g., posterior probability, divergence dates) can be found in Supplementary.

Systematic palaeontology

Carnivora 

Nimravidae 

Eusmilus 

Eusmilus adelos sp. nov.

Holotype: Smithsonian National Museum of Natural History, Washington D.C., USA (USNM) 12820: partially crushed cranium, parts of both dentaries, atlas, axis, 3rd, 5th and 7th cervical vertebrae, three lumbar vertebrae, left: scapula, distal humerus, proximal and distal ends of radius, proximal ulna (Figs. 1, 2, 3, Supplementary Figs. S1–S3).

Etymology: From the Greek adelos, for unseen, unknown, or secret. The specific epithet refers to the unclear taxonomic affiliations these specimens have had in their more than 85 year history of publication. 

Paul Zachary Barrett. 2021. The Largest Hoplophonine and A Complex New Hypothesis of Nimravid Evolution. Scientific Reports. 11, 21078. DOI: 10.1038/s41598-021-00521-1

 twitter.com/nimravenous/status/1453107573788344320

 twitter.com/DhruvFranklin/status/1453122170784256004