Structure and function of the hearts of lizards and snakes

  title={Structure and function of the hearts of lizards and snakes},
  author={Bjarke Jensen and Antoon F. M. Moorman and Tobias Wang},
  journal={Biological Reviews},
With approximately 7000 species, snakes and lizards, collectively known as squamates, are by far the most species‐rich group of reptiles. It was from reptile‐like ancestors that mammals and birds evolved and squamates can be viewed as phylogenetically positioned between them and fishes. Hence, their hearts have been studied for more than a century yielding insights into the group itself and into the independent evolution of the fully divided four‐chambered hearts of mammals and birds… 
Anatomy of the heart of the leatherback turtle
It is concluded that if leatherback turtles have exceptional circulation needs, they are sustained with a relatively large but otherwise typical non-crocodylian reptile heart.
Little variation in the morphology of the atria across 13 orders of birds
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Comparative analysis of avian hearts provides little evidence for variation among species with acquired endothermy
The findings suggest that the transition to high cardiac performance does not necessarily lead to a greater variation in cardiac structure, as among mammals there are 2–3 and 1–7, respectively.
Reptiles as a Model System to Study Heart Development.
Reptiles are placed in their phylogenetic context with a focus on features that are primitive when compared with the homologous features of mammals, including compact chamber walls and a specialized conduction system.
Heart development in the lizards (Varanidae) with the greatest extent of ventricular septation
It is concluded that current concepts of ventricular septum formation apply well to the monitor septa and that there is evolutionary conservation of Ventricular sePTum formation among amniote vertebrates.
Development and evolution of the metazoan heart
It is argued that endothermic ancestors lost the capacity to elevate their body temperature during evolution, resulting in ectothermic modern crocodilians, and a clinically relevant paragraph reviews the occurrence of congenital cardiac malformations in humans as derailments of signaling pathways during embryonic development.
Sequential segmental analysis of the crocodilian heart
By applying a method of analysis and terminology usually restricted to the human heart, this work builds from the considerable existing literature to show neglected and overlooked shared features, such as the offset between the left and right atrioventricular valvar orifices.
Evolution and Development of Ventricular Septation in the Amniote Heart
A novel function of the epicardium in ventricular development in species with partial and complete septation is investigated, to elucidate the evolution and development of this part of the vertebrate heart as well as understand the etiology of septal defects in human congenital heart malformations.
Extreme variation in the atrial septation of caecilians (Amphibia: Gymnophiona)
Atrial septation in caecilians is based on evolutionarily conserved structures but possibly exhibits greater variation than in any other vertebrate order.
Anatomy of the heart with the highest heart rate
The shrew heart, nevertheless, stands out by its relative size, elongation, proportionally large coronary vessels, and extent of pulmonary venous myocardium.


Development of the Hearts of Lizards and Snakes and Perspectives to Cardiac Evolution
It is found that the ventricle and atria grow exponentially, whereas the myocardial volumes of the atrioventricular canal and the muscular outflow tract are stable in the corn snake, and the adult design of the squamate heart is essentially reached halfway through development.
  • K. Johansen
  • Biology
    Annals of the New York Academy of Sciences
  • 1965
It is proposed to review how far a corresponding analysis of the functional characteristics of the lower vertebrate heart has come, with particular reference to the dynamices of the central circulation.
Anatomy of the python heart
It is proposed that intraventricular compact myocardium is an indicator of high-pressure systems and possibly pressure separation in the hearts of varanid lizards.
Form and Function in Reptilian Circulations
Several hypotheses are presented that suggest selective advantages for central vascular shunting in intermittent breathing reptiles with variable body temperature and metabolic rate.
Phylogeny, Ecology, and Heart Position in Snakes
The results suggest that overcoming gravitational pressure gradients in snakes most likely involves the combined action of several cardiovascular and behavioral adaptations in addition to alterations in relative heart location.
Scaling of cardiovascular physiology in snakes
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On the structure of the aortic valves in snakes (Reptilia: Serpentes)
It is suggested that the presence of an interaortic foramen, with its associated valve, could result in an interAortic shunt of blood that potentially alters hemodynamics and flow patterns in the systemic circulation of snakes.
The heart of the South American rattlesnake, Crotalus durissus
A comprehensive study of the cardiac anatomy of the South American rattlesnake (Crotalus durissus) and shows high degrees of blood flow separation in the Crotalus heart, and this can only be explained by the coordinated actions of the septa and the prominent atrioventricular valves.
Mechanisms of heart development in the Japanese lamprey, Lethenteron japonicum
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Gravity and the evolution of cardiopulmonary morphology in snakes.