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The Crocodilian heart is the blood-pumping organ of the Archosaurs (i.e. crocodilians and birds).

Physiology
Crocodilians have a completely separated ventricle with deoxygenated blood from the body, or systemic circulation, in the right ventricle and oxygenated blood from the lungs, or pulmonary circulation, in the left ventricle, as in birds and mammals. Thus, like birds and mammals, the crocodilian heart shows complete separation of the heart into two pumps for a total of four heart chambers; it is thought crocodilians are unique in having an extra heartbeat in one of the upper chambers. However, some species of Crocodilians have regulatory sphincters that prevent unwanted flow of blood through the foramen of Panizza during non-diving.

Origins
It is believed that the unusual cardiac cycle of the crocodilians was inherited from a rare ancestral species, Lynius Watkinus, which later became extinct; the extent to which the crocodilian heart was responsible for this extinction is disputed.

Discovery
Since early times, suspicion that some humans (Homo sapiens) from the subtribe Hominina had crocodilian hearts was prevalent. However, the theory was only confirmed following the invention of Magnetic resonance imaging (MRI) and later by nuclear magnetic resonance (NMR) and NMR spectroscopy.

Case studies
The most prominent example of a human with a crocodilian heart remains Ana Claudia Grove, who was diagnosed at the Cardiac Clinic of Addenbrooke's Hospital, an internationally renowned teaching hospital and research centre in Cambridge, England, with strong affiliations to the University of Cambridge, in February 2019. She was honoured by being named as the species-type for the human-crocodilian hybrid species Ana Crocodilius Groveus.