[Paleontology • 2024] Dinocephalosaurus orientalis Li, 2003: A remarkable marine archosauromorph (Diapsida: Archosauromorpha) from the Middle Triassic of southwestern China

 

Dinocephalosaurus orientalis Li, 2003

Restoration of Dinocephalosaurus orientalis depicted among a shoal of the large, predatory actinopterygian fish, Saurichthys.

in Spiekman, Wang, Zhao, et al., 2024. 

DOI: 10.1017/S175569102400001X

Artwork by Marlene Donnelly.

 

Abstract

The non-archosauriform archosauromorph Dinocephalosaurus orientalis was first described from the Upper Member of the Guanling Formation (late Anisian, Middle Triassic) of Guizhou Province by Li in 2003 on the basis of a complete articulated skull and the first three cervical vertebrae exposed in dorsal to right lateral view. Since then, additional specimens have been discovered in southwestern China. Here, five newly discovered specimens are described for the first time, and redescriptions of the holotype IVPP V13767 and another referred specimen, IVPP V13898, are provided. Together, these permit the description of the complete skeleton of this remarkable long-necked marine reptile. The postcranial skeleton is as much as 6 metres long, and characterised by its long tail and even longer neck. The appendicular skeleton exhibits a high degree of skeletal paedomorphosis recalling that of many sauropterygians, but the skull and neck are completely inconsistent with sauropterygian affinities. The palate does not extend back over the basisphenoid region and lacks any development of the closed condition typical of sauropterygians. The arrangement of cranial elements, including the presence of narial fossae, is very similar to that seen in another long-necked archosauromorph, Tanystropheus hydroides, which at least in part represents a convergence related to an aquatic piscivorous lifestyle. The long and low cervical vertebrae support exceptionally elongate cervical ribs that extend across multiple intervertebral joints and contribute to a ‘stiffening bundle of ribs’ extending along the entire ventral side of the neck, as in many other non-crocopodan archosauromorphs. The functional significance of the extraordinarily elongate neck is hard to discern but it presumably played a key role in feeding, and it is probably analogous to the elongate necks seen in pelagic, long-necked plesiosaurs. Dinocephalosaurus orientalis was almost certainly a fully marine reptile and even gave birth at sea.

Keywords: late Anisian, marine reptile, non-archosauriform, southern China,   

Diapsida Osborn, 1903

Archosauromorpha von Huene, 1946

Dinocephalosauridae Spiekman et al. , 2021

Dinocephalosaurus Li, 2003

Type species: Dinocephalosaurus orientalis Li,2003. 

Distribution: Upper Member of the Guanling Formation (late Anisian, Middle Triassic) near Xinmin in Panxian County, southwestern Guizhou Province, and in Luoping County, eastern Yunnan Province, P.R. China.

Dinocephalosaurus orientalis Li, 2003

Type locality: Xinmin, Panxian County, Guizhou Province, southwestern China.

Horizon: Upper Member of Guanling Formation, Pelsonian, Anisian, Middle Triassic.

 Restoration of Dinocephalosaurus orientalis depicted among a shoal of the large, predatory actinopterygian fish, Saurichthys.

Artwork by Marlene Donnelly.

Summary: 

The Middle Triassic (latest Anisian) marine reptile Dinocephalosaurus orientalis is fully described in detail on the basis of seven beautifully preserved specimens from southwestern Guizhou Province, southern China, five of which are presented for the first time. Characters in the skull and neck are consistent with Dinocephalosaurus orientalis being included within Archosauromorpha. With 32, mostly elongate, cervical vertebrae, it had an extraordinarily long neck that draws comparison with the neck of Tanystropheus hydroides, another aquatic non-crocopodan archosauromorph that has been recorded from the Middle Triassic of both Europe and China. Both taxa share several other cranial features, including a fish-trap type dentition, a distinct antorbital recess and a wide palatal ramus of the pterygoid. The phylogenetic placement of Dinocephalosaurus orientalis is hampered by high levels of homoplasy, but our analysis suggests that the similarities between Dinocephalosaurus orientalis and Tanystropheus hydroides are largely convergent. Instead, the results corroborate the presence of a monophyletic Dinocephalosauridae outside Tanystropheidae. A greater expression of paedomorphosis in the appendicular skeleton and the presence of paddle-shaped autopodia in Dinocephalosaurus orientalis also suggest an adaptation to more open waters than in Tanystropheus hydroides. Dinocephalosaurus orientalis and Tanystropheus sp. were not contemporaries in the eastern Tethys based on current fossil occurrences: all finds of Tanystropheus sp. to date being from latest Ladinian or earliest Carnian sequences. The exact function of the extraordinary long neck of Dinocephalosaurus orientalis is unclear but it almost certainly aided in catching fish, which are preserved in the stomach contents of one of the specimens.

Stephan N.F. SPIEKMAN, Wei WANG, Lijun ZHAO, Olivier RIEPPEL, Nicholas C. FRASER and Chun LI. 2024. Dinocephalosaurus orientalis Li, 2003: A remarkable marine archosauromorph from the Middle Triassic of southwestern China. Earth and Environmental Science Transactions of The Royal Society of Edinburgh. First View; 1 - 33. DOI: 10.1017/S175569102400001X

[PaleoIchthyology • 2024] Harajicadectes zhumini • A New Stem-Tetrapod Fish (Sarcopterygii: Tetrapodomorpha) from the Middle–Late Devonian of central Australia

 

 Harajicadectes zhumini

Choo, Holland, Clement, King, Challands, Young & Long, 2024

 DOI: 10.1080/02724634.2023.2285000  

Illustration by Brian Choo

ABSTRACT

Remote Devonian exposures in central Australia have produced significant but highly fragmentary remains of fish-grade tetrapodomorphs. We describe a new tetrapodomorph from the Middle–Late Devonian (Givetian–Frasnian) Harajica Sandstone Member of the Amadeus Basin, Northern Territory, which is represented by several nearly complete skulls along with much of the body and postcranial skeleton. The new form has a posteriorly broad postparietal shield, broad, triangular extratemporal bones, and a lanceolate parasphenoid. The spiracular openings are particularly large, a character also recorded in elpistostegalians and Gogonasus, demonstrating that these structures, suggestive of spiracular surface air-breathing, appeared independently in widely differing nodes of the stem-tetrapod radiation. A phylogenetic analysis resolves the new form within a cluster of osteolepidid-grade taxa, either as part of a polytomy or as the most basally-branching representative of a clade containing ‘osteolepidids,’ canowindrids, and megalichthyids.

  Harajicadectes zhumini from the Harajica Sandstone Member (Givetian–Frasnian), Northern Territory, Australia, Holotype NTM P6410.
A, photographed as a natural mold in situ as it was discovered in 2016; B, as a whitened latex peel; and C, interpretative drawing.

SYSTEMATIC PALEONTOLOGY

OSTEICHTHYES Huxley, 1880

SARCOPTERYGII Romer, 1955

TETRAPODOMORPHA Ahlberg, 1991

Genus HARAJICADECTES gen. nov.

HARAJICADECTES ZHUMINI, gen. nov. et sp. nov.

Diagnosis—Tetrapodomorph fish with greatly enlarged spiracular openings, comprising over 20% of the total length of the skull-roof, bordered by the tabular, extratemporal, and squamosal. Parietal and postparietals of roughly equal length. Elongate intertemporal that widens anteriorly. Posterior nasals narrower than the anterior and posterior supraorbitals. Median extrascapular tapers anteriorly into a V-shaped recess formed by the large rounded lateral extrascapulars. Elongate lanceolate parasphenoid with denticles larger on the anterior part of the bone. Scales display ridged ornamentation and lack cosmine. Anterior squamation cycloid, abruptly shifting to a rhombic shape on the rear flank.

Etymology—“Harajica Biter.” Named for the Harajica Sandstone Member and the ancient Greek dēktēs (“biter”) in reference to the animal’s large fangs and presumed predatory habits. The species honors Professor Min Zhu of the Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China, for his numerous contributions to early vertebrate paleontology.

Type Locality and Horizon—Harajica Sandstone Member of the Parke Siltstone. Locality 6 of Young (Citation1985), about 2 km southwest of the southern end of Stokes Pass, Amadeus Basin, Northern Territory. Givetian–Frasnian in age (Fig. 1).

Life reconstruction of  Harajicadectes zhumini, a 40 cm long lobe-finned fish that is not too distantly related to the fishes that gave rise to the earliest limbed tetrapods.

(Illustration by Brian Choo, Flinders University)

 

 

Brian Choo, Timothy Holland, Alice M. Clement, Benedict King, Tom Challands, Gavin Young and John A. Long. 2024. A New Stem-Tetrapod Fish from the Middle–Late Devonian of central Australia. Journal of Vertebrate Paleontology. e2285000. DOI: 10.1080/02724634.2023.2285000  

[Paleontology • 2024] Austronaga minuta • A small-sized dinocephalosaurid archosauromorph (Diapsida: Dinocephalosauridae) from the Middle Triassic of Yunnan, southwestern China

 Austronaga minuta

Wang, Lei & Li, 2024

  Researchgate.net/publication/377413090

Abstract

Among numerous marine reptiles discovered in the Triassic eastern Tethys, today’s Southern China, Dinocephalosaurus is a bizarre animal comparable to European Tanystropheus in developing a prominently long neck. These two taxa are respectively assigned to Dinocephalosauridae and Tanystropheidae, and the two families and other basal members collectively form an early-diverging clade of Archosauromorpha. Here we report a new archosauromorph specimen, IVPP V18579, excavated from the lower Middle Triassic (Anisian), from Luoping, Yunnan in southwestern China. Compared with all the hitherto known dinocephalosaurids and tanystropheids, this skeletally mature individual is exclusively similar to Dinocephalosaurus in a number of characteristics, particularly with the long posterodorsal process of the premaxilla extending posteriorly beyond the level of the external nares, the concave posterior margin of the anteroposteriorly broad quadrate, and the strongly expanded distal end of the chevron in most of the caudal vertebrae. However, this reptile is much smaller than Dinocephalosaurus and different from Dinocephalosaurus and the other dinocephalosaurid, Pectodens, in many aspects, such as an anteriorly tapering long rostrum, the dentition composed of short conical teeth with less heterodonty, relatively but obviously tall neural spines of the axis and the anterior cervical vertebrae. Our phylogenetic analysis suggests that the new archosauromorph is a dinocephalosaurid, and then we erect Austronaga minuta gen. et sp. nov. based on this specimen. Detailed comparisons in osteological anatomy and the discussion about its potential aquatic adaptation of this new taxon are also provided.

Key words: Luoping, Yunnan, East Tethys, Triassic, marine reptile, Archosauromorpha, Dinocephalosauridae, osteological anatomy

Diapsida Osborn, 1903

Archosauromorpha Huene, 1946 sensu Dilkes, 1998

Dinocephalosauridae Spiekman et al., 2021

Austronaga minuta gen. et sp. nov.

Etymology: Austronaga, from the Latin “auster” or “austral” meaning south or southern referring to the South China Block where this taxon occurred, combining with “naga”, an Asian mythological figure that is snake-like and associated with water; minuta meaning small refers to the relatively small body size of this animal compared with most of its Triassic marine archosauromorph relatives. 

Wei Wang, Hong Lei and Chun Li. 2024. A small-sized dinocephalosaurid archosauromorph from the Middle Triassic of Yunnan, southwestern China. Vertebrata Palasiatica.  DOI: 10.19615/j.cnki.2096-9899.231013

https://www.vertpala.ac.cn/CN/10.19615/j.cnki.2096-9899.231013

Researchgate.net/publication/377413090_A_small-sized_dinocephalosaurid_archosauromorph_from_the_Middle_Triassic_of_Yunnan_China

 

摘要：现在的中国南方地区在三叠纪时期曾位于特提斯洋东部。在该区域产出的众多海生爬行动物中，恐头龙(Dinocephalosaurus)的形态特化，颈部极度增长，可与时代略晚的长颈龙(Tanystropheus)相比拟。这两种爬行动物分别归属于恐头龙科(Dinocephalosauridae)和长颈龙科(Tanystropheidae), 而这两个科的成员加之另外一些基干物种代表了主龙型类(Archosauromorpha)中一系列早期分异出的支系。报道一件产自云南罗平地区中三叠世安尼期地层的主龙型类成年个体新标本IVPP V18579, 与目前已知的早期主龙型类成员相比，该标本显示出与恐头龙属一致但区别于其他属种的特征，主要包括前颌骨发育有超过外鼻孔后缘的较长后背侧突，方骨前后向较宽大且具有后边缘的凹缺，大部分尾椎上的人字骨带有远端前后向的延展。然而，新标本体型明显小于恐头龙，且显示出与恐头龙属和梳齿龙属(另一恐头龙科成员)不同的鉴别特征，例如吻部窄长、牙齿短锥状且异齿性弱、枢椎和前部颈椎的神经棘显著更高等。基于最新的用于早期主龙型类系统发育分析的特征矩阵，系统发育分析结果确定V18579代表一个新的恐头龙科成员，在恐头龙科中与恐头龙属互为姊妹群关系。于是基于V18579建立了一新属新种：玲珑南蛇龙(Austronaga minuta), 同时对其进行了详细的解剖学特征描述，并讨论了它可能具有的水生适应性。

关键词: 云南罗平, 东特提斯, 三叠纪, 海生爬行动物, 主龙型类, 恐头龙科, 骨骼学解剖

[Paleontology • 2023] Meilifeilong youhao • A New toothless Pterosaur from the Early Cretaceous Jehol Biota with Comments on the Chaoyangopteridae

 Meilifeilong youhao  

Wang, Kellner, Jiang, Chen, Costa, Cheng, Zhang, Vila Nova, de Almeida Campos, Sayão, Rodrigues, Bantim, Saraiva & Zhou, 2023

DOI: 10.1038/s41598-023-48076-7 

twitter.com/paleoTaissa

artwork by Maurilio Oliveira

Abstract

The Chaoyangopteridae is a clade of azhdarchoid pterosaurs that stands out in China, particularly in the Jehol Biota, as a Cretaceous group of medium-sized and high-crested pterosaurs. Herein, we describe a new species, Meilifeilong youhao gen. et sp. nov., based on two specimens, one tentatively referred to this taxon. This new species represents the most complete and well-preserved chaoyangopterid recorded to date. Along with a set of characters (low premaxillary crest above the nasoantorbital fenestra extending posteriorly, posterior premaxillary process arched and curving posteriorly, a slightly convex sternal articulation surface of coracoid, and a fibular shaft close to proximal articulation strongly arched posteriorly), this species also provides new information both on the unknown palatal region of this clade, and on the rarely preserved (in place) ear portion with stapes. Moreover, M. youhao sheds light on paleoecological aspects, while also giving new information about the taxonomic diversity of this peculiar group of Jiufotang pterosaurs.

Systematic Paleontology

Pterosauria Kaup, 1834

Pterodactyloidea Plieninger, 1901

Dsungaripteroidea Young, 1964 sensu Kellner 2001, 2003

Azhdarchoidea Nessov 1984, sensu Kellner 2001, 2003

Chaoyangopteridae Lü et al. 2008

Photo (A) and line drawing (B) of the holotype (IVPP V 16059) of Meilifeilong youhao gen. et sp. nov. Arrows indicate preserved soft tissue.
 Abbreviations: at-ax, atlas-axis; cdv, caudal vertebra; cv, cervical vertebra; dca, distal syncarpal; dv, dorsal vertebrae; fe, femur; fi, fibula; gas, gastralia; hu, humerus; il, ilium; isc, ischium; man, mandible; mcI-IV, metacarpal I-IV; mt, metatarsal; obfo, obturator foramen.; paca, preaxial carpal; ph1-3d4, first to third phalanx of manual digit IV; phd 1–3, phalanx of the manual digit IIII; pphd, phalanx of the pedal digit; ppu, prepubis; prca, proximal syncarpal; ptd, pteroid; pu, pubis; ra, radius; ri, rib; sca-cor; scapulocoracoid; sk, skull; sv sacral vertebra; st, sternum; ta, tarsal; ti, tibia; ul, ulna; l, left; r, right.

 Meilifeilong youhao gen. et sp. nov.
Photo (A) and line drawing (B) of the cranial elements of the holotype (IVPP V 16059) 

Meilifeilong gen. nov.

Type species. Meilifeilong youhao.

Etymology. From the Chinese expressions meili—beautiful, fei—fly, and long—dragon, meaning beautiful flying dragon in allusion to the magnificent preservation of the holotype, IVPP V 16059.

Included species. Meilifeilong sanyainus comb. nov.

Diagnosis. Chaoyangopterid with low premaxillary crest above the nasoantorbital fenestra that extends posteriorly; posterior premaxillary process arched and curving posteriorly; humerus about 20% longer than third phalanx of the wing finger (hu/ph1d4 ~ 1.20).

Meilifeilong youhao sp. nov.

Etymology. Youhao, meaning friendship in mandarin, to celebrate the two-decade continuous collaboration between Chinese and Brazilian paleontologists in pterosaur research since 2003.

Holotype. IVPP V 16059, an almost complete skeleton housed at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, Beijing, China,

Horizon and locality. Xiaotaizi, Jianchang, Huludao City, western Liaoning China; Jiufotang Formation, Early Cretaceous (Barremian-Aptian).

Diagnosis. Chaoyangopterid pterosaur exhibiting the following autapomorphies: sternal articulation surface of coracoid slightly convex; fibular shaft close to proximal articulation strongly arched posteriorly. The new species can be further distinguished from Meilifeilong sanyainus by the following features: posterior premaxillary process more arched; jugal with lacrimal and postorbital processes at a narrower angle (~ 45° contra ~ 55° in Meilifeilong sanyainus); deeper mandibular symphysis; cervical vertebrae 5 slightly longer than cervical 4; rectangular sternum that is wider than long (square in Meilifeilong sanyainus); scapula comparatively longer relative to the coracoid, metatarsal III and IV proportionally shorter than metatarsals I and II.

 Meilifeilong youhao gen. et sp. nov.

artwork: Maurilio Oliveira

 

Xiaolin Wang, Alexander W. A. Kellner, Shunxing Jiang, He Chen, Fabiana R. Costa, Xin Cheng, Xinjun Zhang, Bruno C. Vila Nova, Diogenes de Almeida Campos, Juliana M. Sayão, Taissa Rodrigues, Renan A. M. Bantim, Antônio A. F. Saraiva and Zhonghe Zhou. 2023. A New toothless Pterosaur from the Early Cretaceous Jehol Biota with Comments on the Chaoyangopteridae. Scientific Reports. 3, 22642. DOI: 10.1038/s41598-023-48076-7

 twitter.com/paleoTaissa/status/1737866080184307713

[PaleoIchthyology • 2023] Yanliaomyzon ingensdentes & Y. occisor • The Rise of Predation in Jurassic Lampreys

Yanliaomyzon occisor & Y. ingensdentes 

 Wu, Janvier & Zhang, 2023

DOI: 10.1038/s41467-023-42251-0

Abstract

Lampreys, one of two living lineages of jawless vertebrates, are always intriguing for their feeding behavior via the toothed suctorial disc and life cycle comprising the ammocoete, metamorphic, and adult stages. However, they left a meager fossil record, and their evolutionary history remains elusive. Here we report two superbly preserved large lampreys from the Middle-Late Jurassic Yanliao Biota of North China and update the interpretations of the evolution of the feeding apparatus, the life cycle, and the historic biogeography of the group. These fossil lampreys’ extensively toothed feeding apparatus differs radically from that of their Paleozoic kin but surprisingly resembles the Southern Hemisphere pouched lamprey, which foreshadows an ancestral flesh-eating habit for modern lampreys. Based on the revised petromyzontiform timetree, we argued that modern lampreys’ three-staged life cycle might not be established until the Jurassic when they evolved enhanced feeding structures, increased body size and encountered more penetrable host groups. Our study also places modern lampreys’ origin in the Southern Hemisphere of the Late Cretaceous, followed by an early Cenozoic anti-tropical disjunction in distribution, hence challenging the conventional wisdom of their biogeographical pattern arising from a post-Cretaceous origin in the Northern Hemisphere or the Pangean fragmentation in the Early Mesozoic.

Jurassic lampreys from the Yanliao Biota, China, Yanliaomyzon occisor gen. et sp. nov. and Yanliaomyzon ingensdentes gen. et sp. nov.
a–e Yanliaomyzon occisor gen. et sp. nov., a Photograph of holotype (IVPP V 15830); b Line drawing of the oral disc and dentition of (a), based on Supplementary Fig. 2k and l; c, d Paratype (IVPP V 18956B), photograph (c) and line drawing (d); e Restoration.
 f–h Yanliaomyzon ingensdentes gen. et sp. nov., f Photograph of holotype (IVPP V 16715B), white arrow pointing to the skeletal relics in gut content; g Oral disc and dentition; h Restoration.

Abbreviations: adf, ‘anterior dorsal fin’ (dorsal fin); af, anal fin fold; ba, branchial apparatus; ca, cloaca (anus); cot, circumoral teeth; da, dorsal aorta; dcf, dorsal lobe of caudal fin; dt, oral disc teeth; cf, caudal fin; e, eyes; dt, disc teeth; go, external gill openings; gp, gular pouch; ic, intestine contents; io, infraoral lamina; ll, longitudinal lingual lamina; ll.l, left longitudinal lingual lamina; ll.r, right longitudinal lingual lamina; lv, liver; ns, olfactory organ (nasal sac); oc, otic capsule; od, oral disc; of, oral fimbriae; op, oral papilla(e); paf, precloacal skin fold; pdf, ‘posterior dorsal fin’ (anterior part of caudal fin); pt, piston cartilage; so, supraoral lamina; tl, transverse lingual lamina; vcf, ventral lobe of caudal fin; V1?, ophthalmic ramus of trigeminal nerve?

a–d Oral disc and dentition of Yanliaomyzon ingensdentes gen. et sp. nov., a Photograph (IVPP V 16716B) and b Line drawing; c Photograph (IVPP V 16716A), whitened with ammonium chloride, the white arrow pointing to the imprints of the wrinkles of the gular pouch; d Restoration.
e, f Oral disc and dentition of Yanliaomyzon occisor gen. et sp. nov., e Photograph (IVPP V18956A), whitened with ammonium chloride; f Restoration;
 g Oral disc and dentition of Geotria australis, redrawn from ref. 10.
Abbreviations: cot, circumoral teeth; dt, oral disc teeth; gp, gular pouch; ic, intestine contents; io, infraoral lamina; ll, longitudinal lingual lamina; ll.r, right longitudinal lingual lamina; od, oral disc; of, oral fimbriae; op, oral papilla(e); so, supraoral lamina; tl, transverse lingual lamina.

Systematic paleontology

Order: Petromyzontiformes Berg, 194018

Genus Yanliaomyzon gen. nov.

 

Diagnosis: Stem lampreys with oral discs well-toothed in anterior and lateral fields; anterior and lateral oral disc teeth closely arranged, dorsally truncated, spatulate in shape with the slightly concaved undersurface of the free edge protruding a shallow blade; posterior disc teeth lacking, anterior and lateral circumoral teeth elongate and trihedral in shape; supraoral lamina large and consisting of two stout central cusps flanked by wing-like lateral extensions; transverse lingual lamina very large with the apices of three cusps interlocking with the supraoral lamina in vivo.

 

Etymology: ‘Yanliao’ derives from Yanliao Biota, a Jurassic terrestrial Lagerstätte from North China, where these fossils were discovered; ‘myzon’ (Greek), sucker.

Yanliaomyzon occisor

Diagnosis: The supraoral lamina spanning completely the lateral rims of the oral aperture, with the central cusps flanked immediately by two smaller projections; 16 circumoral teeth; the tail region occupying slightly less than 28% of the total body length.

Etymology: Latin ‘occisor’, meaning ‘killer’, refers to the powerful hunting skill of the species.

Horizon and locality: Tiaojishan Formation, Oxfordian, earliest Late Jurassic, ca. 158.58–160 million years ago (Ma); Daxishan, Linglongta Town, Jianchang County, Liaoning Province (Holotype), and Nanshimen Village, Gangou Town, Qinglong County, Hebei Province (Paratype), China.

Yanliaomyzon ingensdentes gen. et sp. nov.

Diagnosis: The supraoral lamina occupying roughly one-third of the rim of the oral aperture; the transverse lingual lamina almost equaling to the supraoral lamina in width; ca. 23 circumoral teeth; the tail region occupying slightly more than 40% of the total body length.

Etymology: Latin ‘ingens + dentes’, meaning large teeth, refers to the large cuspid laminae on the gouging piston.

 

Horizon and locality: Daohugou beds, Callovian, late Middle Jurassic, ca. 163 Ma in Wubaiding Village, Reshuitang County, Liaoning Province, China.

   

 

Feixiang Wu, Philippe Janvier and Chi Zhang. 2023. The Rise of Predation in Jurassic Lampreys. Nature Communications. 14: 6652. DOI: 10.1038/s41467-023-42251-0

https://phys.org/news/2023-11-species-large-ancient-lampreys-china.html

[PaleoMammalogy • 2023] Amphimachairodus hezhengensis • Origin of Adaptations to Open Environments and Social Behaviour in Sabretoothed Cats (Carnivora: Felidae: Machairodontinae) from the northeastern Border of the Tibetan Plateau

Amphimachairodus hezhengensis

Jiangzuo,  Werdelin, Sanisidro, Yang, Fu, Li, Wang & Deng, 2023

defending their prey (Hezhengia bohlini) 

from two Dinocrocuta gigantea.

 DOI: 10.1098/rspb.2023.0019

Artwork by Oscar Sanisidro.

Highlights: 

• The earliest Amphimachairodus discovered exhibits craniodental adaptation to open environment and social behaviour.

• Adaptations to change in habitat and killing behaviour evolved prior to other traits.

• Adaptatons to open environments and social behaviour first occurred near the Tibetan Plateau, probably due to aridification as the plateau was formed.

Abstract

The iconic sabretooth Homotherium is thought to have hunted cooperatively, but the origin of this behaviour and correlated morphological adaptations are largely unexplored. Here we report the most primitive species of Amphimachairodus (Amphimachairodus hezhengensis sp. nov.), a member of Machairodontini basal to Homotherium, from the Linxia Basin, northeastern border of the Tibetan Plateau (9.8–8.7 Ma). The long snout, laterally oriented and posteriorly located orbit of Amphimachairodus suggest a better ability to observe the surrounding environment, rather than targeting single prey, pointing to an adaptation to the open environment or social behaviour. A pathological forepaw of Amphimachairodus provides direct evidence of partner care. Our analyses of trait evolutionary rates support that traits correlated with killing behaviour and open environment adaptation evolved prior to other traits, suggesting that changes in hunting behaviour may be the major evolutionary driver in the early evolution of the lineage. A. hezhengensis represents one of the most important transitions in the evolution of Machairodontini, leading to adaptation in open environments and contributing to their further dispersal and radiation worldwide. This rapid morphological change is likely to be correlated with increasingly arid environments caused by the rise of the Tibetan Plateau, and competition from abundant large carnivores in this area.

Keywords: Machairodus, Amphimachairodus, Linxia basin, Eastern Asia, competition

 

(a) Cranium of Amphimachairodus hezhengensis sp. nov. HMV2041. a1, dorsal view; a2, anterior view; a3, ventral view; a4, postero-ventral view; a5, lateral view.
(b) Geography of fossil locality.
(c) Pathology of the MC2 and MC3 of Amphimachairodus sp. HMV2047 forepaw.
(d) Large predator contemporary with A. hezhengensis in the Linxia Basin. d1, A. hezhengensis, HMV2041; d2, Dinocrocuta gigantea, HMV2044; d3, Agriotheriini ursid, HMV2046.

 Systematics

Order Carnivora Bowdich, 1821

Family Felidae Batsch, 1788

Subfamily Machairodontinae Gill, 1872

Tribe Machairodontini Gill, 1872

Amphimachairodus Kretzoi, 1929

Diagnosis: machairotont of large size. Rostrum long, and forehead wide. Orbit anterior border located at P4. Glenoid fossa overhung above basicranium. Mastoid process large, and paroccipital moderate to highly reduced. Mandibular flange weak or moderate, cornoid process small. Incisors large with serration, and upper I1 and I2 with laterally posited accessory cusps. P2 variably present. P3 with distinct anterior accessory cusp. P4 with distinct preparastyle and moderate to very small protocone. m1 with metaconid-talonid complex mostly absent.

Included species: Amphimachairodus giganteus (Wagner, 1848), Amphimachairodus horribilis (Schlosser, 1903), Amphimachairodus palanderi (Zdansky, 1924), Amphimachairodus coloradensis (Cook, 1922), Amphimachairodus alvarezi Ruiz-Ramoni et al. 2019 and Amphimachairodus hezhengensis sp. nov.

Amphimachairodus hezhengensis sp. nov.

Machairodus palanderi p.257, Deng et al. 2013

Amphimachairodus sp. p.11 Jiangzuo et al. 2023

Holotype: HMV2041, a nearly complete cranium  

Etymology: After the place (Hezheng Paleozoological Museum, Hezheng, China) where the specimen was found and is currently stored.

Type locality: Houshan, Linxia Basin, Gansu province of northern China.

Chronology and distribution: Thus far only known from the early Late Miocene of northern China.

Diagnosis: medium-sized Amphimachairodus with small incisors and I1 with lingually posited accessory cusps; long C-P3 diastema; presence of P2; relatively small cheek teeth; small P4 preparastyle and moderate protocone.

Differential diagnosis: differs from Machairodus and Nimravides in having different cranial morphology, e.g. lower angle between facial and neurocranial part, wide forehead, retracted orbit and long rostrum, shorter and dorsally arched zygomatic arch, slightly overhanging glenoid fossa, more arched incisor row and more separated lingual accessory cusps in I2, presence of P2, more distinct P4 preparastyle and smaller protocone; differs from Lokotunjailurus in having larger size, longer C-P3 diastema, stronger P3 anterior accessory cusp and more robust P4; differs from other species of Amphimachairodus in having smaller incisors, I1 with two closely located lingual accessory cusps, longer C-P3 diastema, smaller cheek teeth, smaller P4 preparastyle and slightly larger protocone.

Reconstruction of two Amphimachairodus hezhengensis defending their prey (Hezhengia bohlini) from two Dinocrocuta gigantea.

Artwork by Oscar Sanisidro.

Qigao Jiangzuo, Lars Werdelin, Oscar Sanisidro, Rong Yang, Jiao Fu, Shijie Li, Shiqi Wang and Tao Deng. 2023. Origin of Adaptations to Open Environments and Social Behaviour in Sabretoothed Cats from the northeastern Border of the Tibetan Plateau. Proc. R. Soc. B. DOI: 10.1098/rspb.2023.0019

https://phys.org/news/2023-04-trait-tibetan-saber-toothed-cat.html

[PaleoIchthyology • 2023] Foxaspis novemura • Postcranial Disparity of galeaspids (Galeaspida) and the Evolution of Swimming Speeds in Stem-gnathostomes

Foxaspis novemura

Gai, Lin, Shan, Ferrón & Donoghue, 2023

DOI: 10.1093/nsr/nwad050 

 Researchgate.net/publication/368895582

Abstract

Galeaspids are extinct jawless relatives of living jawed vertebrates whose contribution to understanding the evolutionary assembly of the gnathostome bodyplan has been limited by absence of postcranial remains. Here, we describe Foxaspis novemura gen. et sp. nov., based on complete articulated remains from a newly discovered Konservat-Lagerstätte in the Early Devonian (Pragian, ∼410 Ma) of Guangxi, South China. F. novemura had a broad, circular dorso-ventrally compressed headshield, slender trunk and strongly asymmetrical hypochordal tail fin comprised of nine ray-like scale-covered digitations. This tail morphology contrasts with the symmetrical hypochordal tail fin of Tujiaaspis vividus, evidencing disparity in galeaspid postcranial anatomy. Analysis of swimming speed reveals galeaspids as moderately fast swimmers, capable of achieving greater cruising swimming speeds than their more derived jawless and jawed relatives. Our analyses reject the hypothesis of a driven trend towards increasingly active food acquisition which has been invoked to characterize early vertebrate evolution.

Keywords: Galeaspida, jawed vertebrates, evolution, functional morphology, phylogenetics, modelling

Class Galeaspida Tarlo, 1967

Order Polybranchiaspidiformes Liu, 1965

Family Duyunolepididae P'an et Wang, 1978

Genus Foxaspis gen. nov.

Foxaspis novemura gen. et sp. nov.

 

Etymology. After the nine-tailed fox, a creature spoken of in the ancient Chinese mythological bestiary, the Shan-hai Ching (Classic of Mountains and Seas) which is a compilation of mythic geography and myth. Latin novem meaning nine; Latin -ura, meaning tail.

Holotype. A complete headshield articulated with body and tail V30958.1a,bpreserved together with a complete arthrodiran fish (Fig.1A,B).

Locality and horizon. Tongmu Town, Jinxiu County, Laibin City, Guangxi ZhuangAutonomous Region, China, the Xiaoshan Formation, Pragian, Early Devonian (Supplementary Fig. 1).

Zhikun Gai, Xianghong Lin, Xianren Shan, Humberto G. Ferrón and Philip C. J. Donoghue. 2023. Postcranial Disparity of galeaspids and the Evolution of Swimming Speeds in Stem-gnathostomes. National Science Review. nwad050. DOI: 10.1093/nsr/nwad050

  Researchgate.net/publication/368895582_Postcranial_disparity_of_galeaspids_and_the_evolution_of_swimming_speeds_in_stem-gnathostomes

[Paleontology • 2022] Honghesaurus longicaudalis • A Long-tailed Marine Reptile (Sauropterygia: Pachypleurosauridae) from China provides New Insights into the Middle Triassic pachypleurosaur Radiation

 Honghesaurus longicaudalis

Xu, Ren, Zhao, Liao & Feng. 2022

DOI: 10.1038/s41598-022-11309-2

Abstract

Pachypleurosaurs (Pachypleurosauroidea) are a group of small to medium-sized, lizard-like marine reptiles in the Early to Middle Triassic, including Pachypleurosauridae, Keichousauridae and closely related taxa. The group is generally considered as a sauropterygian radiation, but its phylogenetic interrelationships remain highly debated. Here, we present a new pachypleurosaurid, Honghesaurus longicaudalis gen. et sp. nov., from the early Middle Triassic (Anisian, ~ 244 Ma) marine deposits in Luxi, Yunnan, China. The discovery documents the first really long-tailed pachypleurosaur with totally 121 (69 caudal) vertebrae, providing new evidence for the vertebral multiplication and ecological adaption of this group. The long trunk associated with an incredibly long tail could provide Honghesaurus the advantage of maneuverability and energy efficiency for lateral undulatory swimming. Honghesaurus, although possessing a series of autapomorphies, fills the morphological gap between Qianxisaurus from the Ladinian Xingyi Biota and Wumengosaurus from the Anisian Panxian Biota. Phylogenetic studies unite these three pachypleurosaurids as a monophyletic clade above European pachypleurosaurid clades and provide new insights into the interrelationships of this group. Our scenario of pachypleurosaurian phylogeny combined with the stratigraphic data imply that the Tethys Ocean was a west–east corridor for dispersal of pachypleurosaurids from Europe into South China.

Skull and mandible of Honghesaurus longicaudalis gen. et sp. nov., IVPP V30380. 

Photo before (a) and after (b) dusted with ammonium chloride. (c) Line- drawing. (d) Reconstruction in dorsal view. 

an, angular; ar, articular; at, atlas; ax, axis; c, cervical vertebra; den, dentary; en, external naris; eo, exoccipital; f, frontal; j, jugal; m, maxilla; n, nasal; op, opisthotic; p, parietal; pat, proatlas; pm, premaxilla; po, postorbital; pof, postfrontal; prf, prefrontal; pt, pterygoid; q, quadrate; sa, surangular; so, supraoccipital; sq, squamosal; stf, supratemporal fossa.

Honghesaurus longicaudalis gen. et sp. nov., Holotype (IVPP V30380). 

Photo (a) and line-drawing (b) of whole specimen. 

c, cervical vertebra; ca, caudal vertebra; d, dorsal vertebra; s, sacral vertebra.

    

Systematic paleontology

Sauropterygia Owen, 1860 

Eosauropterygia Rieppel, 199 

Pachypleurosauroidea Huene, 1956 

Pachypleurosauridae Nopcsa, 1928 

Honghesaurus longicaudalis gen. et sp. nov.

Holotype: A complete skeleton in the collection of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences (IVPP V30380).

Diagnosis: A pachypleurosaurid distinguishable from other members of this family by the following autapomorphies: snout longer than postorbital portion of skull, 47.8% of skull length; external naris longitudinally retracted, 47.7% of orbital length; supratemporal fossa oval, 46.2% of orbital length; about ten teeth in anteriorly pointed premaxilla; two fossae in retroarticular process; 20 cervical, 29 dorsal, three sacral, and 69 caudal vertebrae; single ossified carpal; and phalangeal formula 2-3-2-4-1 for manus and 2-3-4-5-2 for pes.

Etymology: The genus name refers to Honghe Prefecture, where the holotype was located; the species epithet is derived from longi plus caudalis (Latin for long tail), referring to its incredibly long tail.

Locality and horizon: Luxi, Honghe, Yunnan, China; Second (Upper) Member of Guanling Formation, Pelsonian (~ 244 Ma), Anisian, Middle Triassic. 

   

Guang-Hui Xu, Yi Ren, Li-Jun Zhao, Jun-Ling Liao and Dong-Hao Feng. 2022. A Long-tailed Marine Reptile from China provides New Insights into the Middle Triassic pachypleurosaur Radiation. Scientific Reports. 12, 7396. DOI: 10.1038/s41598-022-11309-2