Objasniti Zapadnoindijsko Područje Zašto Se Tako Zove!
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1 objasniti zapadnoindijsko područje zašto se tako zove! 2 3 4 5 6 7 The first known rodent fossils in South America are represented by the three taxa Cachiyacuy contamanensis, C. kummeli, and Canaanimys maquiensis, as well as teeth from Eobranisamys sp. (Dasyproctidae) and Eospina sp., the latter two found also in the Santa Rosa fauna from the late Eocene or early Oligocene. By the late Oligocene, all superfamilies and most families of caviomorphs are present in the fossil record.[citation needed] During this time, South America was isolated from all other continents. Several hypotheses have been proposed as to how hystricognath rodents colonized this island continent. Most require that a small group of these rodents traveled across ocean bodies atop a raft of mangroves or driftwood. The most common hypothesis suggests that the ancestor to all modern caviomorphs rafted across the Atlantic Ocean (then narrower) from Africa (Lavocat, 1969; Huchon and Douzery, 2000). This is supported by molecular results, which suggest that the Phiomorpha (as restricted to Bathyergidae, Petromuridae, and Thryonomyidae) are sister taxa to the Caviomorpha. In fact, until the discovery of the Laotian rock rat, all modern hystricognath families were restricted to South America, Africa, or had a range that included Africa (Hystricidae). The principal alternative hypothesis is that the caviomorph ancestor arose in Asia and migrated to South America through another continent. Most commonly, North America is cited as the most likely continent (Wood, 1985) as connections between North America and Asia were common via Beringia, and North America appears to have been closer to South America than any other continent at this 8 time. The "Franimorpha" were once proposed as a potential North American rodent group that may represent an ancestor to the Caviomorpha, but most modern researchers consider franimorphs to have been protrogomorphous instead of hystricomorphous. Fossil evidence suggests the Entodacrya may have originated in Asia (Marivaux et al., 2004) and this is cited as potential evidence for an Asian origin for Caviomorpha as well. Likewise, Jenkins et al. (2005) argue that their discovery of a hystricognath rodent family (Laonastidae) exclusive to Asia may be further evidence for an Asian origin of caviomorphs. Alternatively, the caviomorphs may have originated in Asia, but traveled through Africa, Australia and Antarctica, or Africa and Antarctica (noted but not advocated by Huchon and Douzery, 2001). Alternatively they may have originated in Africa and traveled to South America via Antarctica. New World monkeys appear to have colonized South America from Africa at a similar time. Caviomorphs went on to colonize the West Indies as far as the Bahamas, reaching the Greater Antilles by the early Oligocene.[1] This is commonly viewed as another example of oceanic dispersal,[2][3] although a role for a possible land bridge has also been considered. 8 The long-term isolation of South America during most of the Cenozoic produced a highly peculiar terrestrial vertebrate biota, with a wide array of mammal groups, among which caviomorph rodents and platyrrhine primates are Mid- Cenozoic immigrants. In the absence of indisputable pre-Oligocene South American rodents or primates, the mode, timing and biogeography of these extraordinary dispersals remained debated. Here, we describe South America’s oldest known rodents, based on a new diverse caviomorph assemblage from the late Middle Eocene (approx. 41 Ma) of Peru, including five small rodents with three stem caviomorphs. Instead of being tied to the Eocene/Oligocene global cooling and drying episode (approx. 34 Ma), as previously considered, the arrival of caviomorphs and their initial radiation in South America probably occurred under much warmer and wetter conditions, around the Mid-Eocene Climatic Optimum. Our phylogenetic results reaffirm the African origin of South American rodents and support a trans-Atlantic dispersal of these mammals during Middle Eocene times. This discovery further extends the gap (approx. 15 Myr) between first appearances of rodents and primates in South America. 9 The platyrrhine primates, or New World monkeys, are immigrant mammals whose fossil record comes from Tertiary and Quaternary sediments of South America and the Caribbean Greater Antilles1,2. The time and place of platyrrhine origins are some of the most controversial issues in primate palaeontology, although an African Palaeogene ancestry has been presumed by most primatologists3,4. Until now, the oldest fossil records of New World monkeys have come from Salla, Bolivia5,6, and date to approximately 26 million years ago7, or the Late Oligocene epoch. Here we report the discovery of new primates from the ?Late Eocene epoch of Amazonian Peru, which extends the fossil record of primates in South America back approximately 10 million years. The new specimens are important for understanding the origin and early evolution of modern platyrrhine primates because they bear little resemblance to any extinct or living South American primate, but they do bear striking resemblances to Eocene African anthropoids, and our phylogenetic analysis suggests a relationship with African taxa. The discovery of these new primates brings the first appearance datum of caviomorph rodents and primates in South America back into close correspondence, but raises new questions about the timing and means of arrival of these two mammalian groups. 10 11 Prije formiranja prevlake svaki kontinent imao je 26 porodica kopnenih sisavaca, a nakon što se prevlaka formirala 16 porodica uspjelo je priječi na jednu ili drugu stranu. Od ukupno sjevernoameričkih sisavaca 29 rodova proširilo se na jug za vrijeme razdoblja pliocen/pleistocen prije odprilike 2,5 milijuna godina. Oni su uključivali rovke, glodavce, zvijeri (mačke, pse, medvjede), slonove, tapire konje, pekarije, ljame i jelene (Slika 5.7; 5.8; 5.9). Istovremeno su iz Južne Amerike prodrli su pasanci dikobrazi, dikobrazoliki glodavci i tipavci. Slijedili su ih prije 1,5 milijuna godina tobolčari (oposum) i mravojedi. Fauna koja je prešla Panamsku prevlaku bila je prilagođena vegetaciji savana. Stoga se pretpostavlja da je ovaj tip vegetacije tada egzistirao u srednjoj Americi. Tropska kišna šuma razvila se tek krajem pleistocena (Burnham i Graham 1999). Iako je jednaki broj porodica migrirao južno i sjeverno, sjevernoamerički doseljenici bili su mnogo uspješniji od južnoameričkih. U Sjevernoj Americi samo 29 rodova (21%) danas živućih kopnenih sisavaca su potomci južnjačkih useljenika. Nasuprot tome u Južnoj Americi čak 85 rodova (50%) danas živućih kopnenih sisavaca su potomci sjevernjačkih useljenika. Najuspješniji su od njih bili porodice hrčaka Cricetidae koji su u Južnoj Americi evoluirali u 45 različitih rodova svrstanih u tri endemične podporodice: Neotominae, Sigmodontinae, Tylomyinae (ove tri podporodice nazivaju se popularno „miševima i štakorima Novog svijeta“). Razlozi ovakve uspješnosti su različiti. Južna Amerika bila manje povezana nego što li je to bila Sjeverna Amerika i Europa. Tako su se sjevernoamerički doseljenici mogli razvijati neometano oslobođeni kompeticije novonastalih vrsta u Sjevernom svijetu. 12 Megatherium – bio veličine slona, jedan od najvećih kopnenih sisavaca ikad Megatherium is one of the largest land mammals known to have existed, weighing up to 4 tonnes[11] and measuring up to 6 m (20 ft) in length from head to tail.[12][13] It is the largest known ground sloth, as big as modern elephants, and would have only been exceeded in its time by a few species of mammoth. The group is known primarily from its largest species, M. americanum. Megatherium species were members of the abundant Pleistocene megafauna, large mammals that lived during the Pleistocene epoch. Thylacosmilus – tobolčarska sabljozuba “mačka” – izumro ranije, istisnuo ga Smilodon Smilodon – zvijer, mačka Doedicurus – najveći pasanac ikad, bio je dugačak do 4 m, visok oko 1,5m 13 14 15 Marmosa murina – arborealni, noćni tobolčar. svejed. velik 15ak cm (s repom do 20), težak do 250 g 16 Pasanci: danas ima oko 30 vrsta, u nekoliko porodica i rodova. Dasypus are non-territorial, have large progeny, have few predators, and are capable of living in various environments, thus accounting for their large distribution. They are, though, limited by a lack of sufficient insects as a food source and their low metabolic rate, which prevents them from livingincoldclimates.[6] Dasypus originated from South America but has expanded and diversified across numerous countries.[7] The existence of human developments and construction has generally increased the armadillo's ability to expand by facilitating the crossing of previous obstacles. As of 2011, within the United States, they have not yet migrated south due to the lack of rainfall or water availability. Golemi pasanac – danas najvećiživući pasanac, dugačak oko 1,5 s repom (od tog tijelo 1 m, rep 50ak cm), težak do 50 kg u divljini. slabo istražena biologija i ekologija u prirodi, status – ranjiv, zbog lova (zbog mesa) Mravojeda danas ima 5 vrsta (u dvije porodice) Veliki mravojed – najveći mravojed, dugačak do oko 2 m, težak oko 40ak kg. uglavnom živinatluzarazlikuodvećine drugih koji su arborealni. hrani se mravima i termitima, dolazi u travnjačkim i šumskim ekosustavima Tipavaca ima 6 vrsta danas (4 vrste su least concern, 1 vulnerable, 1 critically endangered). Sloth's lower metabolism confines them to the tropics and they adopt thermoregulation behaviors of