Dabbobi masu shayarwa: taƙaitaccen bayanin

Don kwanan wata, dabbobi masu shayarwa suna dauke su daya daga cikin mafi m azuzuwan. Wannan kungiya ne halin da dama da muhimmanci fasali. Bisa ga kiyasin da aka sani da karatu a duniya a yau akwai fiye da dubu biyar mambobi na aji. Ko da yake shi ne ya kamata a lura da cewa wannan adadi ne sosai m, saboda masana kimiyya da kuma suna neman sababbin nau'in kwanan wata.

Dabbobi masu shayarwa da kuma su rarraba

Dabbobi masu shayarwa suna dauke su quite musamman wakilan fauna. Suna rarraba a ko'ina cikin duniya.

Wakilai daga wannan aji za a iya samu a kusan dukan manyan wuraren da Duniya. Wadannan dabbobi da kyau halittun da zafi, bushe hamada sauyin yanayi a Highland yankuna. Za ka iya ganin su a cikin iyakacin duniya yankuna da kuma na wurare masu zafi rainforests. Su ne m ko a cikin ruwa yanayi.

Zai yiwu ne kawai yankunan da ba su lugar da dabbobi masu shayarwa suna cikin ƙasa na Antarctica da zurfin na duniya ba ta tekuna.

Abin sha'awa, yankin na rarraba monotremes dabbobi (misali, da platypus) ne a fili iyakance zuwa yankuna na New Guinea da kuma Australia. Marsupials wakilan rarraba kan tsibirin na Oceania, kazalika a Australia da kuma a cikin ƙasa na nahiyar Amirka. Wani mai ban sha'awa Gaskiyar ita ce, a kan Australian nahiyar da aka sanaki kawai 'yan placental dabbobi masu shayarwa kafin zuwa na farko natsuwa.

Dabbobi masu shayarwa: babban fasali na aji

Kamar yadda aka ambata a riga, wannan rukuni na dabbobi yana da yawan musamman halaye, da nuna babban matakin da kungiyar:

• Kusan viviparous dabbobi masu shayarwa.
• Mãtan shãyar da matasa madara samar a cikin takamaiman gland (af, saboda wannan al'amari dabbobi masu shayarwa samun su suna).
• Class wakilan da takamaiman fatar kan mutum, mukaddashin sebaceous da sunadarin gumi.
• Ga abin da ake kira da hankula dabbobi masu shayarwa homeotherms, ko dumin jiki - da yanayin jikinsu ba ya dogara ne a kan yanayi da kuma yanayi zazzabi.
• A muhimmanci musamman alama ce ta wannan rukuni na dabbobi ne mai kyau-da kwakwalwa, musamman, da karshe na shi. A nan ne cibiyar ta hanyar abin da wakilan ayan zama sosai hadaddun halayyar.
• A dabbobi masu shayarwa kafa auricle, cikin matsanancin kunne canal, kazalika da dukan uku daga cikin auditory ossicles, wanda, ba zato ba tsammani, an modified kashin dadashinsu.
• Domin da 'yan aji ne halin da m hudu gidajen zuciya da kuma hagu aortic baka, wanda samar da rabuwa da jini a kan venous da jijiya (misali, a cikin dabbobi masu rarrafe da venous jijiya jini da ake gauraya a cikin zuciya).
• A rarrabe za a iya daukan da alveolar tsarin da huhu.
• Bugu da ƙari, akwai bambance-bambance a cikin tsari na jini Kwayoyin - ja jini Kwayoyin na wadannan dabbobi ba dauke da nuclei, a numfashi pigment.
• Dabbobi masu shayarwa suna da bakwai vertebrae a cikin mahaifa yankin.
• Ga 'yan wannan aji suna halin da irin hakora (gaban incisors, canines, molars). A wannan yanayin via hakora tushen nutsa cikin zurfin dadashin.

Asalin Dabbobi masu shayarwa

Masana kimiyya yi imani da cewa magabatan zamani dabbobi masu shayarwa sun dabbobi masu rarrafe da ya bayyana a cikin Paleozoic. Wadannan dabbobi har yanzu riƙe wasu kama da halittar dabba mai kafafuwa, musamman, a gaban fata gland da yiwu a biyu occipital condyle.

Musamman ma kusa da dangi na zamani dabba bace-kamar jinsunan suna dauke. Wakilai na wannan kungiyar da aka halin gaban daban-daban hakora (molars, incisors da canines). A babba da ƙananan jaws aka shiga musamman kashi wanda samo asali a cikin dabbobi masu shayarwa auditory ossicles. Amma wakilan da dabbobi masu shayarwa-kamar dadaddun a cikin Upper Triassic.

Tuni a cikin Jurassic lokaci, akwai rabuwa na live-qazanta jinsunan daga waɗanda mambobi cewa sun dage farawa qwai.

A gaskiya, a fili kirkiro ka'idar asalin Dabbobi masu shayarwa ne ba zai yiwu ba, saboda wannan rana, masana binciken burbushin halittu da kuma sauran masana kimiyya ne rayayye da bincike a wannan yanki.