CO2-metabolism in early tetrapods revisited: inferences from osteological correlates of gills, skin and lung ventilation in the fossil record

Lethaia ◽  
2015 ◽  
Vol 49 (4) ◽  
pp. 492-506 ◽  
Author(s):  
Florian Witzmann
Keyword(s):  
Fossil Record ◽  
Lung Ventilation ◽  
Early Tetrapods ◽  
Co2 Metabolism

scholarly journals The Fossil Record of Early Tetrapods: Worker Effort and the End-Permian Mass Extinction

2010 ◽  
Vol 55 (2) ◽  
pp. 229-239 ◽  
Author(s):  
Emma L. Bernard ◽  
Marcello Ruta ◽  
James E. Tarver ◽  
Michael J. Benton
Keyword(s):  
Mass Extinction ◽  
Fossil Record ◽  
Early Tetrapods ◽  
Permian Mass Extinction

scholarly journals Dermal bone in early tetrapods: a palaeophysiological hypothesis of adaptation for terrestrial acidosis

2012 ◽  
Vol 279 (1740) ◽  
pp. 3035-3040 ◽  
Author(s):  
Christine M. Janis ◽  
Kelly Devlin ◽  
Daniel E. Warren ◽  
Florian Witzmann
Keyword(s):  
Carbon Dioxide ◽  
Lung Ventilation ◽  
Ventilation Mode ◽  
Acid Base Balance ◽  
Dermal Bone ◽  
Base Balance ◽  
Lactate Acidosis ◽  
Early Tetrapods ◽  
Calcified Tissues ◽  
Dermal Bones

The dermal bone sculpture of early, basal tetrapods of the Permo-Carboniferous is unlike the bone surface of any living vertebrate, and its function has long been obscure. Drawing from physiological studies of extant tetrapods, where dermal bone or other calcified tissues aid in regulating acid–base balance relating to hypercapnia (excess blood carbon dioxide) and/or lactate acidosis, we propose a similar function for these sculptured dermal bones in early tetrapods. Unlike the condition in modern reptiles, which experience hypercapnia when submerged in water, these animals would have experienced hypercapnia on land, owing to likely inefficient means of eliminating carbon dioxide. The different patterns of dermal bone sculpture in these tetrapods largely correlates with levels of terrestriality: sculpture is reduced or lost in stem amniotes that likely had the more efficient lung ventilation mode of costal aspiration, and in small-sized stem amphibians that would have been able to use the skin for gas exchange.

scholarly journals Locomotory behaviour of early tetrapods from Blue Beach, Nova Scotia, revealed by novel microanatomical analysis

2021 ◽  
Vol 8 (5) ◽  
pp. 210281
Author(s):  
Kendra I. Lennie ◽  
Sarah L. Manske ◽  
Chris F. Mansky ◽  
Jason S. Anderson
Keyword(s):  
Nova Scotia ◽  
Fossil Record ◽  
Early Carboniferous ◽  
Late Devonian ◽  
Ground Reaction Forces ◽  
Limb Bones ◽  
Additional Information ◽  
Reaction Forces ◽  
Early Tetrapods ◽  
Locomotory Behaviour

Evidence for terrestriality in early tetrapods is fundamentally contradictory. Fossil trackways attributed to early terrestrial tetrapods long predate the first body fossils from the Late Devonian. However, the Devonian body fossils demonstrate an obligatorily aquatic lifestyle. Complicating our understanding of the transition from water to land is a pronounced gap in the fossil record between the aquatic Devonian taxa and presumably terrestrial tetrapods from the later Early Carboniferous. Recent work suggests that an obligatorily aquatic habit persists much higher in the tetrapod tree than previously recognized. Here, we present independent microanatomical data of locomotor capability from the earliest Carboniferous of Blue Beach, Nova Scotia. The site preserves limb bones from taxa representative of Late Devonian to mid-Carboniferous faunas as well as a rich trackway record. Given that bone remodels in response to functional stresses including gravity and ground reaction forces, we analysed both the midshaft compactness profiles and trabecular anisotropy, the latter using a new whole bone approach. Our findings suggest that early tetrapods retained an aquatic lifestyle despite varied limb morphologies, prior to their emergence onto land. These results suggest that trackways attributed to early tetrapods be closely scrutinized for additional information regarding their creation conditions, and demand an expansion of sampling to better identify the first terrestrial tetrapods.

Origin and Evolution of the Turtle Body Plan

2020 ◽  
Vol 51 (1) ◽  
pp. 143-166
Author(s):  
Tyler R. Lyson ◽  
Gabriel S. Bever
Keyword(s):  
Fossil Record ◽  
Lung Ventilation ◽  
Body Plan ◽  
Phylogenetic Position ◽  
Evolutionary Trajectory ◽  
Origin And Evolution ◽  
Key Innovation

The origin of turtles and their uniquely shelled body plan is one of the longest standing problems in vertebrate biology. The unfulfilled need for a hypothesis that both explains the derived nature of turtle anatomy and resolves their unclear phylogenetic position among reptiles largely reflects the absence of a transitional fossil record. Recent discoveries have dramatically improved this situation, providing an integrated, time-calibrated model of the morphological, developmental, and ecological transformations responsible for the modern turtle body plan. This evolutionary trajectory was initiated in the Permian (>260 million years ago) when a turtle ancestor with a diapsid skull evolved a novel mechanism for lung ventilation. This key innovation permitted the torso to become apomorphically stiff, most likely as an adaption for digging and a fossorial ecology. The construction of the modern turtle body plan then proceeded over the next 100 million years following a largely stepwise model of osteological innovation.

scholarly journals Palaeophysiology of pH regulation in tetrapods

2020 ◽  
Vol 375 (1793) ◽  
pp. 20190131 ◽  
Author(s):  
Christine M. Janis ◽  
James G. Napoli ◽  
Daniel E. Warren
Keyword(s):  
Carbon Dioxide ◽  
Ph Regulation ◽  
Volume Ratio ◽  
Lung Ventilation ◽  
Acid Base ◽  
Terrestrial Vertebrates ◽  
Mineralized Tissues ◽  
Dermal Bone ◽  
Active Lifestyles ◽  
Early Tetrapods

The involvement of mineralized tissues in acid–base homeostasis was likely important in the evolution of terrestrial vertebrates. Extant reptiles encounter hypercapnia when submerged in water, but early tetrapods may have experienced hypercapnia on land due to their inefficient mode of lung ventilation (likely buccal pumping, as in extant amphibians). Extant amphibians rely on cutaneous carbon dioxide elimination on land, but early tetrapods were considerably larger forms, with an unfavourable surface area to volume ratio for such activity, and evidence of a thick integument. Consequently, they would have been at risk of acidosis on land, while many of them retained internal gills and would not have had a problem eliminating carbon dioxide in water. In extant tetrapods, dermal bone can function to buffer the blood during acidosis by releasing calcium and magnesium carbonates. This review explores the possible mechanisms of acid–base regulation in tetrapod evolution, focusing on heavily armoured, basal tetrapods of the Permo-Carboniferous, especially the physiological challenges associated with the transition to air-breathing, body size and the adoption of active lifestyles. We also consider the possible functions of dermal armour in later tetrapods, such as Triassic archosaurs, inferring palaeophysiology from both fossil record evidence and phylogenetic patterns, and propose a new hypothesis relating the archosaurian origins of the four-chambered heart and high systemic blood pressures to the perfusion of the osteoderms. This article is part of the theme issue ‘Vertebrate palaeophysiology’.

Molecular clock tied to fossil record

Nature ◽  
2004 ◽  
Author(s):  
Emma Marris
Keyword(s):  
Molecular Clock ◽  
Fossil Record

Darwin's two competing phylogenetic trees: marsupials as ancestors or sister taxa?

2012 ◽  
Vol 39 (2) ◽  
pp. 217-233 ◽  
Author(s):  
J. David Archibald
Keyword(s):  
Fossil Record ◽  
Evolutionary Biology ◽  
Phylogenetic Trees ◽  
Charles Darwin ◽  
The Other ◽  
Charles Lyell ◽  
Single Origin ◽  
Molecular Studies ◽  
Richard Owen ◽  
First Time

Studies of the origin and diversification of major groups of plants and animals are contentious topics in current evolutionary biology. This includes the study of the timing and relationships of the two major clades of extant mammals – marsupials and placentals. Molecular studies concerned with marsupial and placental origin and diversification can be at odds with the fossil record. Such studies are, however, not a recent phenomenon. Over 150 years ago Charles Darwin weighed two alternative views on the origin of marsupials and placentals. Less than a year after the publication of On the origin of species, Darwin outlined these in a letter to Charles Lyell dated 23 September 1860. The letter concluded with two competing phylogenetic diagrams. One showed marsupials as ancestral to both living marsupials and placentals, whereas the other showed a non-marsupial, non-placental as being ancestral to both living marsupials and placentals. These two diagrams are published here for the first time. These are the only such competing phylogenetic diagrams that Darwin is known to have produced. In addition to examining the question of mammalian origins in this letter and in other manuscript notes discussed here, Darwin confronted the broader issue as to whether major groups of animals had a single origin (monophyly) or were the result of “continuous creation” as advocated for some groups by Richard Owen. Charles Lyell had held similar views to those of Owen, but it is clear from correspondence with Darwin that he was beginning to accept the idea of monophyly of major groups.

Sign in / Sign up

Export Citation Format

Share Document