Evolutionary Trends of Triassic Ammonoids

Monnet, Claude; Brayard, Arnaud; Brosse, Morgane

doi:10.1007/978-94-017-9633-0_2

Cited by 5 publications

(5 citation statements)

References 120 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ontogenetic analysis.-Ammonoid generic diversity reached its maximum during the Triassic Period (Brayard et al, 2009). At present, few studies have investigated trends in morphological disparity of Triassic ammonoids (Monnet et al, 2015). McGowan (2004McGowan ( , 2005 and Brosse et al (2013) carried out important foundational research in this field.…”

Section: Speciesmentioning

confidence: 99%

Ontogenetic analysis of Anisian (Middle Triassic) ptychitid ammonoids from Nevada, USA

Bischof

Lehmann

2020

J. Paleontol.

View full text Add to dashboard Cite

Ptychites is among the most widely distributed ammonoid genera of the Triassic and is namesake of a family and superfamily. However, representatives of the genus mostly show low-level phenotypic disparity. Furthermore, a large number of taxa are based on only a few poorly preserved specimens, creating challenges to determine ptychitid taxonomy. Consequently, a novel approach is needed to improve ptychitid diversity studies. Here, we investigate Ptychites spp. from the middle and late Anisian of Nevada. The species recorded include Ptychites embreei n. sp., which is distinguished by an average conch diameter that is much smaller and shows a more evolute coiling than most of its relatives. The new species ranges from the Gymnotoceras mimetus to the Gymnotoceras rotelliformis zones, which makes it the longest-ranging species of the genus. For the first time, the ontogenetic development of Ptychites was obtained from cross sections where possible. Cross-sectioning highlights unique ontogenetic trajectories in ptychitids. This demonstrates that, despite showing little phenotypic disparity, Ptychites was highly ontogenetically differentiated, and thus the high taxonomic diversity at the species level is justified for the species investigated. UUID: http://zoobank.org/5abe2487-8a00-4b48-adc7-ec7db7a097f7

show abstract

Section: Speciesmentioning

confidence: 99%

Ontogenetic analysis of Anisian (Middle Triassic) ptychitid ammonoids from Nevada, USA

Bischof

Lehmann

2020

J. Paleontol.

View full text Add to dashboard Cite

show abstract

“…Furthermore, taxonomic diversity and morphological disparity of Triassic ammonoids were probably decoupled ( McGowan, 2004 ; McGowan, 2005 ; Brosse et al, 2013 ). At present, only a few studies have investigated trends in morphological disparity of Triassic ammonoids ( Monnet, Brayard & Brosse, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Ontogeny of highly variable ceratitid ammonoids from the Anisian (Middle Triassic)

Bischof

Schlüter

Korn

et al. 2021

PeerJ

View full text Add to dashboard Cite

Ammonoids reached their greatest diversity during the Triassic period. In the early Middle Triassic (Anisian) stage, ammonoid diversity was dominated by representatives of the family Ceratitidae. High taxonomic diversity can, however, be decoupled from their morphologic disparity. Due to its high phenotypic variability, the high diversity of ceratitids of the Anisian of Nevada was initially assumed to be caused by artificial over-splitting. This study aims to contribute data to settle this issue by applying geometric morphometrics methods, using landmarks and semi-landmarks, in the study of ontogenetic cross-sections of ammonoids for the first time. The results reveal that alterations in ontogenetic trajectories, linked to heterochronic processes, lead to the morphologic diversification of the species studied herein. Our knowledge, based on these ontogenetic changes, challenge the traditional treatment of species using solely adult characters for their distinction. This study furthermore demonstrates that the high diversity of the Anisian ammonoid assemblages of Nevada based on the traditional nomenclatoric approach is regarded to be reasonably accurate.

show abstract

“…There were mass extinction events at the end of the Permian and Triassic when drastic taxonomic turnovers of ammonoid fauna occurred (e.g., House, 1988 ; Monnet, Brayard & Brosse, 2015 ; Brayard & Bucher, 2015 ; Longridge & Smith, 2015 ). In the Early Triassic and Early Jurassic, origination rates of ammonoids were high (Ceratitida originated in the Triassic and Lytoceratina and Ammonitina originated in the Jurassic; Neige & Rouget, 2015 ; Yacobucci, 2015 ; Longridge & Smith, 2015 ), which probably indicate radiations into open niche followed mass extinction events.…”

Section: Discussionmentioning

confidence: 99%

Geological duration of ammonoids controlled their geographical range of fossil distribution

Wani

2017

PeerJ

View full text Add to dashboard Cite

The latitudinal distributions in Devonian–Cretaceous ammonoids were analyzed at the genus level, and were compared with the hatchling sizes (i.e., ammonitella diameters) and the geological durations. The results show that (1) length of temporal ranges of ammonoids effected broader ranges of fossil distribution and paleobiogeography of ammonoids, and (2) the hatchling size was not related to the geographical range of fossil distribution of ammonoids. Reducing the influence of geological duration in this analysis implies that hatchling size was one of the controlling factors that determined the distribution of ammonoid habitats at any given period in time: ammonoids with smaller hatchling sizes tended to have broader ammonoid habitat ranges. These relationships were somewhat blurred in the Devonian, Carboniferous, Triassic, and Jurassic, which is possibly due to (1) the course of development of a reproductive strategy with smaller hatchling sizes in the Devonian and (2) the high origination rates after the mass extinction events.

show abstract

Evolutionary Trends of Triassic Ammonoids

Cited by 5 publications

References 120 publications

Ontogenetic analysis of Anisian (Middle Triassic) ptychitid ammonoids from Nevada, USA

Ontogenetic analysis of Anisian (Middle Triassic) ptychitid ammonoids from Nevada, USA

Ontogeny of highly variable ceratitid ammonoids from the Anisian (Middle Triassic)

Geological duration of ammonoids controlled their geographical range of fossil distribution

Contact Info

Product

Resources

About