A New Tritylodontid from the Cave Sandstone of South Africa

Fourie, S.

doi:10.1038/198201a0

Cited by 22 publications

(15 citation statements)

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“…These innovations appear concomitantly with the key mammalian traits of endothermy, mastication, and lactation that require increased locomotor activity and efficiency. Evidence of such a change in locomotory performance is seen not only in the advent of the cross-couplet linkage proposed here, but in the appearance of the mammalian-grade pelvis (reduced pubis and anteriorly projecting ileum) (14) and the change to less sprawling, more parasagittal pelvic limb posture at the level of the tritylodontids (15). Reliance on the cross-couplet system would appear to constrain animals to coupletdominated symmetrical gaits, which is true for generalized marsupials (for example, Monodelphis and Didelphis) and monotremes (7).…”

mentioning

confidence: 67%

Hypaxial Motor Patterns and the Function of Epipubic Bones in Primitive Mammals

Reilly

White

2003

Science

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Since the first description of epipubic bones in 1698, their functions and those of the associated abdominal muscles of monotremes and marsupial mammals have remained unresolved. We show that each epipubic bone is part of a kinetic linkage extending from the femur, by way of the pectineus muscle, to the epipubic bone, through the pyramidalis and rectus abdominis muscles on one side of the abdomen, and through the contralateral external and internal oblique muscles to the vertebrae and ribs of the opposite side. This muscle series is activated synchronously as the femur and contralateral forelimb are retracted during the stance phase in locomotion. The epipubic bone acts as a lever that is retracted (depressed) to stiffen the trunk between the diagonal limbs that support the body during each step. This cross-couplet kinetic linkage and the stiffening function of the epipubic bone appear to be the primitive conditions for mammals.

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mentioning

confidence: 67%

Hypaxial Motor Patterns and the Function of Epipubic Bones in Primitive Mammals

Reilly

White

2003

Science

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“…a retention or replacement of a portion of the reptilian puboischiadic plate and that this took place during the general posteriorward displacement of the pelvis." Therefore it is not surprising that in tritylodonts, which are undoubtedly derived from cynodonts and which have a mammalian pelvis with a rotated pubis, epipubic bones do occur (Fourie, 1962).…”

Section: Pelvis and Hindlimbmentioning

confidence: 99%

Cynodont Postcranial Anatomy and the “Prototherian” Level of Mammalian Organization

Jenkins

1970

Evolution

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“…Mayulestes is more derived than Pucadelphys and Andinodelphys in having a small alisphenoid hypotympanic sinus and in lacking a prootic canal, two borhyaenoid synapomorphies 9,12 . Mayulestes exhibits a complex of dental adaptations to a hypercarnivorous diet, independently evolved in several groups of mammals 2,7,9 . The presence of a large nasolacrimal contact in Mayulestes is likely to be a plesiomorphic feature because it is found in other borhyaenoids 10,12 , cynodonts, non-therian mammals, and Vincelestes.…”

mentioning

confidence: 99%

Epipubic bones in eutherian mammals from the Late Cretaceous of Mongolia

Novacek

Rougier

Wible

et al. 1997

Nature

110

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An important transformation in the evolution of mammals was the loss of the epipubic bones. These are elements projecting anteriorly from the pelvic girdle into the abdominal region in a variety of Mesozoic mammals, related tritylodonts, marsupials and monotremes but not in living eutherian (placental) mammals. Here we describe a new eutherian from the Late Cretaceous period of Mongolia, and report the first record of epipubic bones in two distinct eutherian lineages. The presence of epipubic bones and other primitive features suggests that these groups occupy a basal position in the Eutheria. It has been argued that the epipubic bones support the pouch in living mammals, but epipubic bones have since been related to locomotion and suspension of the litter mass of several attached, lactating offspring. The loss of the epipubic bones in eutherians can be related to the evolution of prolonged gestation, which would not require prolonged external attachment of altricial young. Thus the occurrence of epipubic bones in two Cretaceous eutherians suggests that the dramatic modifications connected with typical placental reproduction may have been later events in the evolution of the Eutheria.

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A New Tritylodontid from the Cave Sandstone of South Africa

Cited by 22 publications

References 1 publication

Hypaxial Motor Patterns and the Function of Epipubic Bones in Primitive Mammals

Hypaxial Motor Patterns and the Function of Epipubic Bones in Primitive Mammals

Cynodont Postcranial Anatomy and the “Prototherian” Level of Mammalian Organization

Epipubic bones in eutherian mammals from the Late Cretaceous of Mongolia

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