A new baenid turtle, Saxochelys gilberti, gen. et sp. nov., from the uppermost cretaceous (Maastrichtian) Hell Creek Formation: sexual dimorphism and spatial niche partitioning within the most speciose group of Late Cretaceous turtles (project)

10.7934/p3756 ◽  
2020 ◽  
Author(s):  
T Lyson ◽  
J Sayler ◽  
W Joyce
Keyword(s):  
Sexual Dimorphism ◽  
Late Cretaceous ◽  
Niche Partitioning ◽  
Hell Creek Formation ◽  
Spatial Niche

Ostracoda from the Santonian–Campanian (Upper Cretaceous) Nenjiang and Sifangtai formations, Songliao Basin, northeastern China

2021 ◽  
pp. 1-23
Author(s):  
Yunqi Ye ◽  
Dangpeng Xi ◽  
Lixin Sun ◽  
Dermeval Aparecido Do Carmo ◽  
Lucas Silveira Antonietto ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Northeastern China ◽  
Songliao Basin ◽  
Unique Material ◽  
China And Japan ◽  
Far Eastern

Abstract Despite the abundant literature on limnic Cretaceous ostracode faunas, the database on mid-Late Cretaceous taxa is still scarce. The Songliao Basin in northeastern China preserves a diverse assemblage of ostracode fossils from the Santonian–Campanian Nenjiang and Sifangtai formations. This rather unique material is of major importance to comprehend Early to mid-Late Cretaceous (Cenomanian–Campanian) limnic ostracode faunas and therefore the evolution of Late Cretaceous basins in China. A study of this fauna was conducted to detail the taxonomy of ostracode species from members 1 and 2 of the Nenjiang and Sifangtai formations in the Songliao Basin. Well-preserved specimens of 14 ostracode species were recovered from samples of the ZKY2-1 well in southwestern Songliao Basin: Scabriculocypris liaukhenensis Liu in Netchaeva et al., 1959, Ilyocyprimorpha netchaevae Su in Netchaeva et al., 1959, Cypridea acclinia Netchaeva in Netchaeva et al., 1959, Cypridea cavernosa Galeeva, 1955, Cypridea gracile Netchaeva in Netchaeva et al., 1959, Cypridea lepida Ye in DOFEAD, 1976, Cypridea squalida Sou in Netchaeva et al., 1959, Fabaeformiscandona? Disjuncta (Hao in Hao et al., 1974), Lycopterocypris profunda Lübimova, 1956, Mongolocypris magna (Hou, 1958), Mongolocypris tera (Su in Netchaeva et al., 1959), Talicypridea obliquecostae (Szczechura and Błaszyk, 1970), Talicypridea reticulata (Szczechura, 1978) and Renicypris renalata (Su in Hao et al., 1974). Four of the species identified received emended descriptions and diagnoses. Other important results include the first discussion on sexual dimorphism in Cypridea acclinia and Fabaeformiscandona? disjuncta, the first study on the ontogeny of Ilyocyprimorpha netchaevae, and the reassignment of Cypridea liaukhenensis to the genus Scabriculocypris. Several species recorded herein are also found in other continental far-eastern Asian basins, while genera range from worldwide to far-eastern Asian distribution; these results support strong affinities among faunas of Mongolia, China, and Japan.

scholarly journals A new two-fingered dinosaur sheds light on the radiation of Oviraptorosauria

2020 ◽  
Vol 7 (10) ◽  
pp. 201184
Author(s):  
Gregory F. Funston ◽  
Tsogtbaatar Chinzorig ◽  
Khishigjav Tsogtbaatar ◽  
Yoshitsugu Kobayashi ◽  
Corwin Sullivan ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Late Cretaceous ◽  
Southern China ◽  
Niche Partitioning

Late Cretaceous trends in Asian dinosaur diversity are poorly understood, but recent discoveries have documented a radiation of oviraptorosaur theropods in China and Mongolia. However, little work has addressed the factors that facilitated this diversification. A new oviraptorid from the Late Cretaceous of Mongolia sheds light on the evolution of the forelimb, which appears to have played a role in the radiation of oviraptorosaurs. Surprisingly, the reduced arm has only two functional digits, highlighting a previously unrecognized occurrence of digit loss in theropods. Phylogenetic analysis shows that the onset of this reduction coincides with the radiation of heyuannine oviraptorids, following dispersal from southern China into the Gobi region. This suggests expansion into a new niche in the Gobi region, which relied less on the elongate, grasping forelimbs inherited by oviraptorosaurs. Variation in forelimb length and manus morphology provides another example of niche partitioning in oviraptorosaurs, which may have made possible their incredible diversity in the latest Cretaceous of Asia.

scholarly journals The morphological diversity of Osedax worm borings (Annelida: Siboglinidae)

2014 ◽  
Vol 94 (7) ◽  
pp. 1429-1439 ◽  
Author(s):  
Nicholas D. Higgs ◽  
Adrian G. Glover ◽  
Thomas G. Dahlgren ◽  
Craig R. Smith ◽  
Yoshihiro Fujiwara ◽  
...  
Keyword(s):  
Niche Partitioning ◽  
Three Dimensional ◽  
Morphological Diversity ◽  
Morphological Data ◽  
Micro Computed Tomography ◽  
Fossil Bones ◽  
Spatial Niche ◽  
Multiple Species ◽  
Root Tissues ◽  
Marine Worms

Marine worms in the genus Osedax, have specialized ‘root’ tissues used to bore into the bones of decomposing vertebrate skeletons and obtain nutrition. We investigated the borings of nine Osedax species, using micro computed tomography to quantitatively describe the morphology of the borings and provide three-dimensional reconstructions of the space occupied by Osedax root tissues inside the bone. Each Osedax species displayed a consistent boring morphology in any given bone, but these differed between bones. In bones where multiple species coexisted there was limited evidence for spatial niche partitioning by Osedax root tissues inside the bones investigated here. The new morphological data may be applied to Osedax traces in fossil bones, showing that borings can be used to indicate minimum species richness in these bones.

scholarly journals The shell morphology of the latest Cretaceous (Maastrichtian) trionychid turtle Helopanoplia distincta

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4169 ◽  
Author(s):  
Walter G. Joyce ◽  
Tyler R. Lyson
Keyword(s):  
Phylogenetic Analysis ◽  
North Dakota ◽  
Late Cretaceous ◽  
Type Specimen ◽  
Shell Morphology ◽  
Surface Sculpture ◽  
Fine Grained ◽  
Hell Creek Formation ◽  
The Past ◽  
Metaplastic Bone

Background Helopanoplia distincta is an extinct soft-shelled turtle (Pan-Trionychidae) for which the type specimen is a fragmentary costal and the inguinal notch portion of the left hypoplastron from the Late Cretaceous (Maastrichtian) Lance Formation of Wyoming, USA that bear a distinct surface sculpture pattern consisting of raised tubercles. Over the course of the past few decades, a number of additional, fragmentary specimens from the Late Cretaceous (Maastrichtian) Hell Creek Formation of Montana and North Dakota have been referred to this taxon based on the presence of these tubercles, but a more complete understanding of the anatomy and phylogenetic relationships of this distinctive soft-shelled turtle is still outstanding. Methods We here figure and describe shell remains of eight fossils referable to Helopanoplia distincta from the Hell Creek Formation of Montana and North Dakota that, in combination, document nearly all aspects of the shell morphology of this taxon. We furthermore explore the relationships of this fossil turtle by inserting it into a modified phylogenetic analysis of pan-trionychid relationships. Results The new fossil material thoroughly supports the validity of Helopanoplia distincta. In addition to its unique surface sculpture pattern, this turtle can be diagnosed relative to all other named pan-trionychids by the presence of a distinct corner along the margin of costals II, the complete covering of costal ribs I–VI by metaplastic bone, midline contact of the main plastral elements, hyoplastral shoulder, presence of a lateral, upturned margin on the hyo/hypoplastron that is covered dorsally and laterally by sculptured metaplastic bone, a single, lateral hyoplastral process, and the apomorphic presence of fine scallops along the margin of costals VIII, formation of a laterally embraced, rounded nuchal, anteriorly rounded costals I, distally expanded costals II, and narrow costals VII. A phylogenetic analysis places Helopanoplia distincta as sister to the clade formed by Plastomenus thomasii and Hutchemys spp., thereby confirming its identity as a plastomenid. The vast majority of Helopanoplia distincta material has been recovered from fine-grained overbank deposits, thereby supporting the hypothesis that this turtle favored ponded waters.

Sexual dimorphism in feeding apparatus and niche partitioning in juvenile jumbo squid Dosidicus gigas

2018 ◽  
Vol 607 ◽  
pp. 99-112 ◽  
Author(s):  
Y Gong ◽  
RI Ruiz-Cooley ◽  
ME Hunsicker ◽  
Y Li ◽  
X Chen
Keyword(s):  
Sexual Dimorphism ◽  
Niche Partitioning ◽  
Feeding Apparatus ◽  
Dosidicus Gigas ◽  
Jumbo Squid
Sign in / Sign up

Export Citation Format

Share Document