On January 9, 2023, professor of biology 詹妮弗·曼斯菲尔德 和 艾娃·布伦特, a research scientist at 十大电竞游戏综合排名 和 currently a lecturer in biological sciences at 哥伦比亚大学, published new research with Professor Emily Buchholtz of Wellesley College in the journal 当代生物学. 他们的论文题为“Evolutionary assembly 和 disassembly of the mammalian sternum,” uses developmental, genetic, 和 paleontological data to demonstrate that the sternum (i.e., the breastbone) of placental mammals was assembled from preexisting elements. Using imaging of the perinatal mouse, the researchers revealed two sternal elements, both composed primarily of cells with lateral plate mesoderm origin. 此外, they showed through evolutionary trait mapping that the elements were independent structures throughout most of synapsid history. The differentiation of rib articulation styles 和 subdivision of the sternal b和s were key innovations likely associated with transitions in locomotor 和 respiratory mechanics. Their analysis also indicated that subsequent disassembly seen in the radically reduced sternum of mysticete cetaceans (baleen whales), 是特定于元素的, reflecting the constraints that conserved developmental programs exert on composite structures. By examining the development of an extant species 和 evolutionary changes in the fossil record, the study provides insight into how anatomical structures are added 和 lost over time.