Intraspecific variation of hatchling size in Late Cretaceous ammonoids from Hokkaido, Japan: implication for planktic duration at early ontogenetic stage

Lethaia ◽  
2010 ◽  
Vol 44 (3) ◽  
pp. 287-298 ◽  
Author(s):  
AMANE TAJIKA ◽  
RYOJI WANI
Keyword(s):  
Intraspecific Variation ◽  
Late Cretaceous ◽  
Ontogenetic Stage ◽  
Early Ontogenetic Stage ◽  
Hatchling Size

scholarly journals Arenysaurus ardevoli, first paleoneuroanatomical description of a European hadrosaurid

2014 ◽  
Author(s):  
Penélope Cruzado-Caballero ◽  
Josep Fortuny ◽  
Sergio Llacer ◽  
José Ignacio JI Canudo
Keyword(s):  
North America ◽  
Inner Ear ◽  
Late Cretaceous ◽  
Cerebral Hemisphere ◽  
3D Model ◽  
General Pattern ◽  
Semicircular Canals ◽  
Major Axis ◽  
Ontogenetic Stage ◽  
And Behavior

The neuroanatomy of hadrosaurid dinosaurs is well known from North America and Asia. In Europe only a few cranial remains have been recovered with the braincase. Arenysaurus is the first European endocast for which the paleoneuroanatomy has been studied. The resulting data have enabled us to draw ontogenetic, phylogenetic and functional inferences. Arenysaurus preserves the endocast and the inner ear. This cranial material was CT-scanned, and a 3D-model was generated. The endocast morphology supports a general pattern for hadrosaurids with some characters that distinguish to a subfamily level, such as a brain cavity anteroposteriorly shorter or the angle of the major axis of the cerebral hemisphere to the horizontal in lambeosaurines. Both characters are present in the endocast of Arenysaurus. Moreover, osteological features indicate an adult ontogenetic stage while some paleoneuroanatomical features are indicative of a subadult ontogenetic stage and even a juvenile ontogenetic stage. Finally, a comparison with other hadrosaurids reveals that the low values for the angle of the dural peak may be an autapomorphy exclusive to the Parasaurolophus genus. It is hypothesized that the presence of puzzling characters that suggest different ontogenetic stages for this specimen, may reflect some degree of dwarfism in Arenysaurus. Regarding the inner ear, its structure shows differences from the ornithopod clade with respect to the height of the semicircular canals. These differences could lead to a decrease in the compensatory movements of eyes and head, with important implications for the paleobiology and behavior of hadrosaurid taxa such as Edmontosaurus, Parasaurolophus and Arenysaurus. These differences in the vestibular system could be used as a phylogenetical signal. The endocranial morphology of European hadrosaurids sheds new light on the evolution of this group and may reflect the conditions in the archipelago where these animals lived during the Late Cretaceous.

scholarly journals Intraspecific Variation through Ontogeny in Late Cretaceous Ammonites

2019 ◽  
Vol 2019 (3922) ◽  
pp. 1 ◽  
Author(s):  
Carina Klein ◽  
Neil H. Landman
Keyword(s):  
Intraspecific Variation ◽  
Late Cretaceous

Effects of environmental warming during early life history on libellulid odonates

2017 ◽  
Vol 95 (6) ◽  
pp. 373-382 ◽  
Author(s):  
D.N. Frances ◽  
J.Y. Moon ◽  
S.J. McCauley
Keyword(s):  
Life History ◽  
Intraspecific Variation ◽  
Climate Warming ◽  
Early Life ◽  
Development Time ◽  
Early Life History ◽  
Thermal Variation ◽  
Egg Development ◽  
Measured Time ◽  
Hatchling Size

Climate warming affects ectotherms globally, yet we know little regarding the variability in species’ responses to warming, particularly in early life stages. Additionally, intraspecific variation in response to warming is understudied but may determine species’ resilience to warming. To assess how temperature affects egg development rate in co-occurring dragonfly species, we manipulated temperature (range: 22–31 °C) and measured time to hatching. Warming decreased egg development time across all species, indicating that while climate warming will advance hatching phenology, maintained synchrony in hatching order will likely not affect species interactions. Our second experiment examined early life-history responses to warming in the dot-tailed whiteface (Leucorrhinia intacta (Hagen, 1861)) dragonfly. We measured time to hatching, hatchling size, growth rate, and survival at four temperatures (23–30 °C), including a treatment with increased thermal variation. Warming resulted in smaller hatchlings with increased growth and mortality rates, whereas higher thermal variation did not have effects different from those of warming alone. We observed significant intraspecific variation in the responses to warming in both egg development time and hatchling size and this variation was correlated with date of oviposition. High levels of intraspecific variation may be important in buffering populations from the effects of climate warming.

scholarly journals First Record of a living Platycopida (Crustacea, Ostracoda) from Antarcticwaters and a Discussion on Cytherella serratula (Brady, 1880)

Zootaxa ◽  
2008 ◽  
Vol 1866 (1) ◽  
pp. 349 ◽  
Author(s):  
SIMONE N. BRANDÃO
Keyword(s):  
New Species ◽  
Southern Ocean ◽  
Intraspecific Variation ◽  
Late Cretaceous ◽  
First Record ◽  
Review Of The Literature ◽  
Antarctic Region ◽  
Fossil Species ◽  
O2 Concentration ◽  
The Antarctic

Previous records of Platycopida (Ostracoda) from the Antarctic region of the Southern Ocean include only a few fossil species from the Late Cretaceous to the Palaeocene: Cytherelloidea megaspirocostata Majoran & Widmark, 1998, [sic] Cytherella serratula (Brady, 1880), plus seven species left in open nomenclature. The present study documents the first record of a living platycopid from the Antarctic region and describes Cytherella rwhatleyi sp. nov. as new. Comparison among specimens collected at stations 60° longitude and 10° of latitude apart from each other show that very little intraspecific variation in outline and ornamentation of the valves, as well as on the hemipenis is presented by this new species. Otherwise, clear differences on valve and hemipenis are observed between different species (herein, Jellinek & Swanson 2003). Review of the literature indicates that several species (with great differences in valve outline and ornamentation) have been erroneously assigned to Cytherella serratula (Brady, 1880) demonstrating that this so-called cosmopolitan taxon is in truth most probably restricted to bathyal depths of the Northwestern Atlantic. Finally, the abundances of Cytherella rwhatleyi sp. nov. in the samples studied herein (considering O2 concentration measurements) contradict the proposed relationship between Platycopida and O2 concentration in water masses (Whatley et al. 2003).

scholarly journals Reassessment of a juvenile Daspletosaurus from the Late Cretaceous of Alberta, Canada with implications for the identification of immature tyrannosaurids

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jared T. Voris ◽  
Darla K. Zelenitsky ◽  
François Therrien ◽  
Philip J. Currie
Keyword(s):  
Late Cretaceous ◽  
Phylogenetic Analyses ◽  
Ontogenetic Stage ◽  
Ontogenetic Changes ◽  
Diagnostic Features ◽  
Taxonomic Affinity ◽  
Small Juvenile ◽  
Juvenile Individual ◽  
Dinosaur Park Formation ◽  
Upper Campanian

AbstractDaspletosaurus is a large tyrannosaurine found in upper Campanian deposits of Alberta and Montana. Although several large subadult and adult individuals of this taxon are known, only one juvenile individual, TMP 1994.143.1, has been identified. This specimen has played a key role in the idea that juvenile tyrannosaurid individuals are difficult to differentiate among species. Here the taxonomic affinity of TMP 1994.143.1 is reassessed in light of a juvenile tyrannosaurine postorbital recently discovered in the Dinosaur Park Formation of Alberta. Anatomical comparisons and phylogenetic analyses reveal that TMP 1994.143.1 is referable to the albertosaurine Gorgosaurus libratus, whereas the new postorbital belongs to a small juvenile Daspletosaurus. This taxonomic reassignment of TMP 1994.143.1 results in the juvenile ontogenetic stage of Daspletosaurus being known only from two isolated cranial elements. The new postorbital provides insights into early Daspletosaurus ontogeny, revealing that the cornual process developed earlier or faster than in other tyrannosaurids. Although some ontogenetic changes in the postorbital are found to be unique to Daspletosaurus, overall changes are most consistent with those of other large tyrannosaurines. Our results also show that diagnostic features develop early in ontogeny, such that juveniles of different tyrannosaurid species are easier to differentiate than previously thought.

scholarly journals Cranial ornamentation in the Late Cretaceous nodosaurid ankylosaurHungarosaurus

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11010
Author(s):  
Attila Ősi ◽  
János Magyar ◽  
Károly Rosta ◽  
Matthew Vickaryous
Keyword(s):  
Individual Differences ◽  
Sexual Dimorphism ◽  
Late Cretaceous ◽  
Sister Group ◽  
Ontogenetic Stage ◽  
Size Classes ◽  
Number Of Species ◽  
Interspecific Recognition

Bony cranial ornamentation is developed by many groups of vertebrates, including ankylosaur dinosaurs. To date, the morphology and ontogenetic origin of ankylosaurian cranial ornamentation has primarily focused on a limited number of species from only one of the two major lineages, Ankylosauridae. For members of the sister group Nodosauridae, less is known. Here, we provide new details of the cranial anatomy of the nodosauridHungarosaurusfrom the Santonian of Europe. Based on a number of previously described and newly identified fragmentary skulls and skull elements, we recognize three different size classes ofHungarosaurus. We interpret these size classes as representing different stages of ontogeny. Cranial ornamentation is already well-developed in the earliest ontogenetic stage represented herein, suggesting that the presence of outgrowths may have played a role in intra- and interspecific recognition. We find no evidence that cranial ornamentation inHungarosaurusinvolves the contribution of coossified osteoderms. Instead, available evidence indicates that cranial ornamentation forms as a result of the elaboration of individual elements. Although individual differences and sexual dimorphism cannot be excluded, the observed variation inHungarosauruscranial ornamentation appears to be associated with ontogeny.

scholarly journals Arenysaurus ardevoli, first paleoneuroanatomical description of a European hadrosaurid

2014 ◽  
Author(s):  
Penélope Cruzado-Caballero ◽  
Josep Fortuny ◽  
Sergio Llacer ◽  
José Ignacio JI Canudo
Keyword(s):  
North America ◽  
Inner Ear ◽  
Late Cretaceous ◽  
Cerebral Hemisphere ◽  
3D Model ◽  
General Pattern ◽  
Semicircular Canals ◽  
Major Axis ◽  
Ontogenetic Stage ◽  
And Behavior

The neuroanatomy of hadrosaurid dinosaurs is well known from North America and Asia. In Europe only a few cranial remains have been recovered with the braincase. Arenysaurus is the first European endocast for which the paleoneuroanatomy has been studied. The resulting data have enabled us to draw ontogenetic, phylogenetic and functional inferences. Arenysaurus preserves the endocast and the inner ear. This cranial material was CT-scanned, and a 3D-model was generated. The endocast morphology supports a general pattern for hadrosaurids with some characters that distinguish to a subfamily level, such as a brain cavity anteroposteriorly shorter or the angle of the major axis of the cerebral hemisphere to the horizontal in lambeosaurines. Both characters are present in the endocast of Arenysaurus. Moreover, osteological features indicate an adult ontogenetic stage while some paleoneuroanatomical features are indicative of a subadult ontogenetic stage and even a juvenile ontogenetic stage. Finally, a comparison with other hadrosaurids reveals that the low values for the angle of the dural peak may be an autapomorphy exclusive to the Parasaurolophus genus. It is hypothesized that the presence of puzzling characters that suggest different ontogenetic stages for this specimen, may reflect some degree of dwarfism in Arenysaurus. Regarding the inner ear, its structure shows differences from the ornithopod clade with respect to the height of the semicircular canals. These differences could lead to a decrease in the compensatory movements of eyes and head, with important implications for the paleobiology and behavior of hadrosaurid taxa such as Edmontosaurus, Parasaurolophus and Arenysaurus. These differences in the vestibular system could be used as a phylogenetical signal. The endocranial morphology of European hadrosaurids sheds new light on the evolution of this group and may reflect the conditions in the archipelago where these animals lived during the Late Cretaceous.

rDNA Methylation in Hypericum perforatum Diploids and Tetraploids

2003 ◽  
Vol 58 (11-12) ◽  
pp. 895-897 ◽  
Author(s):  
Jana Halušková ◽  
Benye Liu ◽  
Ludger Beerhues
Keyword(s):  
Hypericum Perforatum ◽  
Gene Dosage ◽  
Ontogenetic Stage ◽  
Early Ontogenetic Stage

Abstract The effect of the gene dosage on the expression of rRNAs was studied in Hypericum perforatum. The methylation levels of rDNA were analysed using the isoschizomers MspI and HpaII and eleven additional methylation-sensitive enzymes. No differences in rDNA methylation were observed between diploids and tetraploids at an early ontogenetic stage.

scholarly journals Baby tyrannosaurid bones and teeth from the Late Cretaceous of western North America

2021 ◽  
pp. 1-22
Author(s):  
Gregory F. Funston ◽  
Mark J. Powers ◽  
S. Amber Whitebone ◽  
Stephen L. Brusatte ◽  
John B. Scannella ◽  
...  
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Critical Period ◽  
Tooth Development ◽  
Western North America ◽  
Apex Predators ◽  
Search Image ◽  
Nesting Habits ◽  
Horseshoe Canyon Formation ◽  
Hatchling Size

Tyrannosaurids were the apex predators of Late Cretaceous Laurasia and their status as dominant carnivores has garnered considerable interest since their discovery, both in the popular and scientific realms. As a result, they are well studied and much is known of their anatomy, diversity, growth, and evolution. In contrast, little is known of the earliest stages of tyrannosaurid development. Tyrannosaurid eggs and embryos remain elusive, and juvenile specimens — although known — are rare. Perinatal tyrannosaurid bones and teeth from the Campanian–Maastrichtian of western North America provide the first window into this critical period of the life of a tyrannosaurid. An embryonic dentary (cf. Daspletosaurus) from the Two Medicine Formation of Montana, measuring just 3 cm long, already exhibits distinctive tyrannosaurine characters like a “chin” and a deep Meckelian groove, and reveals the earliest stages of tooth development. When considered together with a remarkably large embryonic ungual from the Horseshoe Canyon Formation of Alberta, minimum hatchling size of tyrannosaurids can be roughly estimated. A perinatal premaxillary tooth from the Horseshoe Canyon Formation likely pertains to Albertosaurus sarcophagus and it shows small denticles on the carinae. This tooth shows that the hallmark characters that distinguish tyrannosaurids from other theropods were present early in life and raises questions about the ontogenetic variability of serrations in premaxillary teeth. Sedimentary and taphonomic similarities in the sites that produced the embryonic bones provide clues to the nesting habits of tyrannosaurids and may help to refine the prospecting search image in the continued quest to discover baby tyrannosaurids.

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