| chorioallantoic and yolk sac placentation in the dassie rat petromus typicus and its significance for the evolution of hystricognath rodents. | placental characters are most important in understanding the evolutionary history of hystricognath rodents of which some act as animal models for human pregnancy. the data available deal mostly with species native to south america, but the current paper presents novel findings on chorioallantoic and yolk sac placentation in an old world hystricognath and discusses its significance for the evolution of the group. several hystricognath stem species characters are verified for petromus, such as the ... | 2007 | 17586042 |
| the subplacenta in octodon degus and petromus typicus--two hystricognath rodents without significant placental lobulation. | until now, defining characters of hystricognath rodents have been the subplacenta and the lobulation of the main chorioallantoic placenta. however, recent studies have revealed hystricognaths without marked lobulation, which is a plesiomorphic condition of the group. the question thus arises whether the subplacenta of these taxa is structurally homologous to that of other hystricognaths. therefore, subplacental morphology and ontogeny were investigated in octodon and petromus by conventional lig ... | 2007 | 17016808 |
| evolutionary transformations of chorioallantoic placental characters in rodentia with special reference to hystricognath species. | the aim of this paper is to reconstruct the evolution of chorioallantoic placental characters in rodentia. the analysis is based on pre-existing hypotheses of rodent relationships and the tracing of character evolution. data on 64 rodent species of 49 genera are derived from the literature. new results refer to the hystricognath species petromus typicus a. smith, 1831 and octodon degus (molina, 1782). this comprehensive analysis confirms that the stem species pattern of rodentia is characterised ... | 2003 | 12950036 |