Dinosaurs

Dinosaurs (Greek δεινόσαυρος, deinosauros) is the dominant vertebrate animals of terrestrial ecosystems for over 160 million years old, from Old Triassic period (about 230 million years ago) until the end of the Cretaceous period (about 65 million years ago), when many of them became extinct in the Cretaceous-Tertiary extinction event. Ten thousands of bird species alive today have been classified as dinosaurs.

The discovery of a primitive bird Archaeopteryx was the first time in 1861 hinted close kinship between dinosaurs and birds. Besides the existence of fossilized feather impressions, Archaeopteryx was very similar to a small predator dinosaur Compsognathus. Since then research has identified the theropod dinosaurs are most likely as a direct ancestor of birds, most paleontologists now think of birds as the only surviving dinosaurs, and some suggest that dinosaurs and birds should be grouped in a biology class. [1] In addition to birds, crocodiles other close relatives of dinosaurs that survived until now .. Such as dinosaurs and birds, alligators also a member of Archosauria, a group of reptiles that first appeared in the Permian period is very old and dominating in the middle Triassic period.

During the first half of the 20th century, many communities of scientists believe dinosaurs as cold-blooded animals are dumb and slow. However, many studies conducted since the 1970s (called renaissance of dinosaurs) have supported the view that dinosaurs were active animals with a high metabolism and adaptation to diverse social interactions. The resulting changes in scientific understanding of dinosaurs gradually filtered into popular consciousness.

Since the first dinosaur fossil identified in the early nineteenth century, are assembled into the framework of dinosaurs show that major ones in museums around the world. Dinosaurs became popular world culture and continues. They became a topic in the best-selling books and films (most known for Jurassic Park), and new discoveries regularly disclosed in the media

The term "dinosaur" (UK, dinosaur) proposed in 1842 by Sir Richard Owen and came from the Greek δεινός (deinos) "terrible, strong, great" + σαῦρος (sauros) "lizard". The term dinosaur is sometimes used informally to describe other prehistoric reptiles like pelycosaurus Dimetrodon, the winged pterosaurs, and ichthyosaurs, plesiosaurs and Mosasaurus, although none of these animals which is a dinosaur.

Etymology
Taxon dinosaur was formally named in 1842 by a British paleontologist Richard Owen, who menggunakanna to refer to "tribe or sub-order of reptiles Sauria" which became known in Britain and around the world. The term is derived from the ancient Greek word δεινός (deinos which means "terrible", "strong", or "great") and σαύρα (Saura which means "lizard" or "reptile"). Although the taxonomic name is often interpreted as a reference to the teeth, claws, and other terrible features of dinosaurs, Owen is only intended to warn about the size and keangungan them. In everyday English "dinosaur" is sometimes used to describe objects or old fogy or fail, even though the dinosaurs 160 million years in power and his descendants, birds, a large number and diverse in the world.

Dinosaurus

Dinosaurus (Yunani δεινόσαυρος, deinosauros) adalah hewan bertulang belakang dominan di ekosistem darat selama lebih dari 160 juta tahun, dari periode Trias Tua (sekitar 230 juta tahun yang lalu) sampai dengan akhir periode Kapur (sekitar 65 juta tahun yang lalu), ketika banyak dari mereka punah pada peristiwa kepunahan Kapur-Tersier. Sepuluh ribuan jenis burung yang hidup sekarang telah diklasifikasikan sebagai dinosaurus.

Penemuan burung primitif tahun 1861 Archaeopteryx pertamakalinya memberi petunjuk kekerabatan erat antara dinosaurus dan burung. Selain adanya kesan bulu yang memfosil, Archaeopteryx sangat mirip dinosaurus pemangsa berukuran kecil Compsognathus. Sejak itu penelitian telah mengidentifikasi dinosaurus theropoda paling mungkin sebagai moyang langsung dari burung; kebanyakan paleontolog sekarang menganggap burung sebagai satu-satunya dinosaurus yang masih bertahan, dan beberapa menyarankan bahwa dinosaurus dan burung mesti dikelompokkan dalam satu kelas biologi.^[1] Selain burung, buaya adalah kerabat dekat lain dari dinosaurus yang bertahan sampai kini.. Seperti dinosaurus dan burung, buaya juga anggota Archosauria, kelompok reptil yang muncul pertama kali pada periode Perm sangat tua dan mendominasi pada periode Trias tengah.

Selama paruh pertama dari abad ke 20, banyak komunitas ilmuwan percaya dinosaurus sebagai hewan berdarah dingin yang bodoh dan lambat. Namun, banyak penelitian yang dilakukan sejak tahun 1970-an (disebut renaisans dinosaurus) telah mendukung pandangan bahwa dinosaurus adalah binatang yang aktif dengan metabolisme yang tinggi dan adaptasi yang beragam untuk interaksi sosial. Perubahan yang dihasilkan pada pemahaman ilmiah tentang dinosaurus lambat laun tersaring menjadi kesadaran populer.

Sejak fosil dinosaurus pertama dikenali pada awal abad sembilan belas, rangka dinosaurus yang dirangkai menjadi pertunjukan yang poluler di museum-museum di seluruh dunia. Dinosaurus menjadi budaya dunia dan terus populer. Mereka menjadi topik di buku-buku terlaris dan film-film (paling dikenal Jurassic Park), dan penemuan-penemuan baru secara teratur diungkapkan di media

Istilah "dinosaurus" (Inggris, dinosaur) dikemukakan tahun 1842 oleh Sir Richard Owen dan bersal dari bahasa Yunani δεινός (deinos) "mengerikan, kuat, hebat" + σαῦρος (sauros) "kadal". Istilah dinosaurus kadang-kadang digunakan secara tidak resmi untuk menggambarkan reptil prasejarah lain seperti pelycosaurus Dimetrodon, pterosaurus yang bersayap, serta ichthyosaurus, plesiosaurus dan mosasaurus, meskipun tak satupun dari hewan-hewan ini yang merupakan dinosaurus.

Etimologi

Takson Dinosauria dinamai secara formal tahun 1842 oleh seorang paleontolog Inggris Richard Owen, yang menggunakanna untuk merujuk pada "suku atau sub-ordo dari reptil Sauria" yang kemudian dikenal di Inggris dan seluruh dunia. Istilah tersebut didapat dari kata bahasa Yunani kuno δεινός (deinos yang berarti "mengerikan", "kuat", atau "hebat") dan σαύρα (saura yang berarti "kadal" or "reptil"). Meskipun nama taksonomik tersebut sering diinterpretasikan sebagai rujukan pada gigi, cakar, dan ciri mengerikan lain dari dinosaurus, Owen hanya bermaksud mengingatkan tentang ukuran dan keangungan mereka. Dalam bahasa Inggris sehari-hari "dinosaur" kadang-kadang dipakai untuk menggambarkan benda atau orang kolot atau gagal, meski dinosaurus berkuasa 160 juta tahun dan keturunannya, burung, berjumlah banyak serta beraneka ragam di seluruh dunia.

Biawak Komodo

Komodo, atau yang selengkapnya disebut biawak komodo (Varanus komodoensis), adalah spesies kadal terbesar di dunia yang hidup di pulau Komodo, Rinca, Flores, Gili Motang, dan Gili Dasami di Nusa Tenggara. Biawak ini oleh penduduk asli pulau Komodo juga disebut dengan nama setempat ora.

Termasuk anggota famili biawak Varanidae, dan klad Toxicofera, komodo merupakan kadal terbesar di dunia, dengan rata-rata panjang 2-3 m. Ukurannya yang besar ini berhubungan dengan gejala gigantisme pulau, yakni kecenderungan meraksasanya tubuh hewan-hewan tertentu yang hidup di pulau kecil terkait dengan tidak adanya mamalia karnivora di pulau tempat hidup komodo, dan laju metabolisme komodo yang kecil. Karena besar tubuhnya, kadal ini menduduki posisi predator puncak yang mendominasi ekosistem tempatnya hidup.

Komodo ditemukan oleh peneliti barat tahun 1910. Tubuhnya yang besar dan reputasinya yang mengerikan membuat mereka populer di kebun binatang. Habitat komodo di alam bebas telah menyusut akibat aktivitas manusia dan karenanya IUCN memasukkan komodo sebagai spesies yang rentan terhadap kepunahan. Biawak besar ini kini dilindungi di bawah peraturan pemerintah Indonesia dan sebuah taman nasional, yaitu Taman Nasional Komodo, didirikan untuk melindungi mereka.

Anatomi dan m[pheorfologi

Di alam bebas, komodo dewasa biasanya memiliki massa sekitar 70 kilogram, namun komodo yang dipelihara di penangkaran sering memiliki bobot tubuh yang lebih besar. Spesimen liar terbesar yang pernah ada memiliki panjang sebesar 3.13 meter dan berat sekitar 166 kilogram, termasuk berat makanan yang belum dicerna di dalam perutnya. Meski komodo tercatat sebagai kadal terbesar yang masih hidup, namun bukan yang terpanjang. Reputasi ini dipegang oleh biawak Papua (Varanus salvadorii). Komodo memiliki ekor yang sama panjang dengan tubuhnya, dan sekitar 60 buah gigi yang bergerigi tajam sepanjang sekitar 2.5 cm, yang kerap diganti. Air liur komodo sering kali bercampur sedikit darah karena giginya hampir seluruhnya dilapisi jaringan gingiva dan jaringan ini tercabik selama makan. Kondisi ini menciptakan lingkungan pertumbuhan yang ideal untuk bakteri mematikan yang hidup di mulut mereka. Komodo memiliki lidah yang panjang, berwarna kuning dan bercabang. Komodo jantan lebih besar daripada komodo betina, dengan warna kulit dari abu-abu gelap sampai merah batu bata, sementara komodo betina lebih berwarna hijau buah zaitun, dan memiliki potongan kecil kuning pada tenggorokannya. Komodo muda lebih berwarna, dengan warna kuning, hijau dan putih pada latar belakang hitam.

Fisiologi

Komodo tak memiliki indera pendengaran, meski memiliki lubang telinga. Biawak ini mampu melihat hingga sejauh 300 m, namun karena retinanya hanya memiliki sel kerucut, hewan ini agaknya tak begitu baik melihat di kegelapan malam. Komodo mampu membedakan warna namun tidak seberapa mampu membedakan obyek yang tak bergerak. Komodo menggunakan lidahnya untuk mendeteksi rasa dan mencium stimuli, seperti reptil lainnya, dengan indera vomeronasal memanfaatkan organ Jacobson, suatu kemampuan yang dapat membantu navigasi pada saat gelap. Dengan bantuan angin dan kebiasaannya menelengkan kepalanya ke kanan dan ke kiri ketika berjalan, komodo dapat mendeteksi keberadaan daging bangkai sejauh 4—9.5 kilometer. Lubang hidung komodo bukan merupakan alat penciuman yang baik karena mereka tidak memiliki sekat rongga badan. Hewan ini tidak memiliki indra perasa di lidahnya, hanya ada sedikit ujung-ujung saraf perasa di bagian belakang tenggorokan.

Sisik-sisik komodo, beberapa di antaranya diperkuat dengan tulang, memiliki sensor yang terhubung dengan saraf yang memfasilitasi rangsang sentuhan. Sisik-sisik di sekitar telinga, bibir, dagu dan tapak kaki memiliki tiga sensor rangsangan atau lebih.

Komodo pernah dianggap tuli ketika penelitian mendapatkan bahwa bisikan, suara yang meningkat dan teriakan ternyata tidak mengakibatkan agitasi (gangguan) pada komodo liar. Hal ini terbantah kemudian ketika karyawan Kebun Binatang London ZSL, Joan Proctor melatih biawak untuk keluar makan dengan suaranya, bahkan juga ketika ia tidak terlihat oleh si biawak.

Ekologi, perilaku dan cara hidup

Komodo secara alami hanya ditemui di Indonesia, di pulau Komodo, Flores dan Rinca dan beberapa pulau lainnya di Nusa Tenggara. Hidup di padang rumput kering terbuka, sabana dan hutan tropis pada ketinggian rendah, biawak ini menyukai tempat panas dan kering ini. Mereka aktif pada siang hari, walaupun kadang-kadang aktif juga pada malam hari. Komodo adalah binatang yang penyendiri, berkumpul bersama hanya pada saat makan dan berkembang biak. Reptil besar ini dapat berlari cepat hingga 20 kilometer per jam pada jarak yang pendek; berenang dengan sangat baik dan mampu menyelam sedalam 4.5 meter; serta pandai memanjat pohon menggunakan cakar mereka yang kuat. Untuk menangkap mangsa yang berada di luar jangkauannya, komodo dapat berdiri dengan kaki belakangnya dan menggunakan ekornya sebagai penunjang. Dengan bertambahnya umur, komodo lebih menggunakan cakarnya sebagai senjata, karena ukuran tubuhnya yang besar menyulitkannya memanjat pohon.

Untuk tempat berlindung, komodo menggali lubang selebar 1–3 meter dengan tungkai depan dan cakarnya yang kuat. Karena besar tubuhnya dan kebiasaan tidur di dalam lubang, komodo dapat menjaga panas tubuhnya selama malam hari dan mengurangi waktu berjemur pada pagi selanjutnya. Komodo umumnya berburu pada siang hingga sore hari, tetapi tetap berteduh selama bagian hari yang terpanas. Tempat-tempat sembunyi komodo ini biasanya berada di daerah gumuk atau perbukitan dengan semilir angin laut, terbuka dari vegetasi, dan di sana-sini berserak kotoran hewan penghuninya. Tempat ini umumnya juga merupakan lokasi yang strategis untuk menyergap rusa.

Perilaku makan

Komodo adalah hewan karnivora. Walaupun mereka kebanyakan makan daging bangkai, penelitian menunjukkan bahwa mereka juga berburu mangsa hidup dengan cara mengendap-endap diikuti dengan serangan tiba-tiba terhadap korbannya. Ketika mangsa itu tiba di dekat tempat sembunyi komodo, hewan ini segera menyerangnya pada sisi bawah tubuh atau tenggorokan. Komodo dapat menemukan mangsanya dengan menggunakan penciumannya yang tajam, yang dapat menemukan binatang mati atau sekarat pada jarak hingga 9,5 kilometer.

Komodo muda di Rinca yang makan bangkai kerbau.

Reptil purba ini makan dengan cara mencabik potongan besar daging dan lalu menelannya bulat-bulat sementara tungkai depannya menahan tubuh mangsanya. Untuk mangsa berukuran kecil hingga sebesar kambing, bisa jadi dagingnya dihabiskan sekali telan. Isi perut mangsa yang berupa tumbuhan biasanya dibiarkan tak disentuh. Air liur yang kemerahan dan keluar dalam jumlah banyak amat membantu komodo dalam menelan mangsanya. Meski demikian, proses menelan tetap memakan waktu yang panjang; 15–20 menit diperlukan untuk menelan seekor kambing. Komodo kadang-kadang berusaha mempercepat proses menelan itu dengan menekankan daging bangkai mangsanya ke sebatang pohon, agar karkas itu bisa masuk melewati kerongkongannya. Dan kadang-kadang pula upaya menekan itu begitu keras sehingga pohon itu menjadi rebah. Untuk menghindari agar tak tercekik ketika menelan, komodo bernafas melalui sebuah saluran kecil di bawah lidah, yang berhubungan langsung dengan paru-parunya. Rahangnya yang dapat dikembangkan dengan leluasa, tengkoraknya yang lentur, dan lambungnya yang dapat melar luar biasa memungkinkan komodo menyantap mangsa yang besar, hingga sebesar 80% bobot tubuhnya sendiri dalam satu kali makan. Setelah makan, komodo menyeret tubuhnya yang kekenyangan mencari sinar matahari untuk berjemur dan mempercepat proses pencernaan. Kalau tidak, makanan itu dapat membusuk dalam perutnya dan meracuni tubuhnya sendiri. Dikarenakan metabolismenya yang lamban, komodo besar dapat bertahan dengan hanya makan 12 kali setahun atau kira-kira sekali sebulan. Setelah daging mangsanya tercerna, komodo memuntahkan sisa-sisa tanduk, rambut dan gigi mangsanya, dalam gumpalan-gumpalan bercampur dengan lendir berbau busuk, gumpalan mana dikenal sebagai gastric pellet. Setelah itu komodo menyapukan wajahnya ke tanah atau ke semak-semak untuk membersihkan sisa-sisa lendir yang masih menempel; perilaku yang menimbulkan dugaan bahwa komodo, sebagaimana halnya manusia, tidak menyukai bau ludahnya sendiri.

Dalam kumpulan, komodo yang berukuran paling besar biasanya makan lebih dahulu, diikuti yang berukuran lebih kecil menurut hirarki. Jantan terbesar menunjukkan dominansinya melalui bahasa tubuh dan desisannya; yang disambut dengan bahasa yang sama oleh jantan-jantan lain yang lebih kecil untuk memperlihatkan pengakuannya atas kekuasaan itu. Komodo-komodo yang berukuran sama mungkin akan berkelahi mengadu kekuatan, dengan cara semacam gulat biawak, hingga salah satunya mengaku kalah dan mundur; meskipun adakalanya yang kalah dapat terbunuh dalam perkelahian dan dimangsa oleh si pemenang.

Mangsa biawak komodo amat bervariasi, mencakup aneka avertebrata, reptil lain (termasuk pula komodo yang bertubuh lebih kecil), burung dan telurnya, mamalia kecil, monyet, babi hutan, kambing, rusa, kuda, dan kerbau. Komodo muda memangsa serangga, telur, cecak, dan mamalia kecil. Kadang-kadang komodo juga memangsa manusia dan mayat yang digali dari lubang makam yang dangkal. Kebiasaan ini menyebabkan penduduk pulau Komodo menghindari tanah berpasir dan memilih mengubur jenazah di tanah liat, serta menutupi atasnya dengan batu-batu agar tak dapat digali komodo. Ada pula yang menduga bahwa komodo berevolusi untuk memangsa gajah kerdil Stegodon yang pernah hidup di Flores. Komodo juga pernah teramati ketika mengejutkan dan menakuti rusa-rusa betina yang tengah hamil, dengan harapan agar keguguran dan bangkai janinnya dapat dimangsa; suatu perilaku yang juga didapati pada predator besar di Afrika.

Karena tak memiliki sekat rongga badan, komodo tak dapat menghirup air atau menjilati air untuk minum (seperti kucing). Alih-alih, komodo ‘mencedok’ air dengan seluruh mulutnya, lalu mengangkat kepalanya agar air mengalir masuk ke perutnya.

Bisa dan bakteri

Pada akhir 2005, peneliti dari Universitas Melbourne, Australia, menyimpulkan bahwa biawak Perentie (Varanus giganteus) dan biawak-biawak lainnya, serta kadal-kadal dari suku Agamidae, kemungkinan memiliki semacam bisa. Selama ini diketahui bahwa luka-luka akibat gigitan hewan-hewan ini sangat rawan infeksi karena adanya bakteria yang hidup di mulut kadal-kadal ini, akan tetapi para peneliti ini menunjukkan bahwa efek langsung yang muncul pada luka-luka gigitan itu disebabkan oleh masuknya bisa berkekuatan menengah. Para peneliti ini telah mengamati luka-luka di tangan manusia akibat gigitan biawak Varanus varius, V. scalaris dan komodo, dan semuanya memperlihatkan reaksi yang serupa: bengkak secara cepat dalam beberapa menit, gangguan lokal dalam pembekuan darah, rasa sakit yang mencekam hingga ke siku, dengan beberapa gejala yang bertahan hingga beberapa jam kemudian. Sebuah kelenjar yang berisi bisa yang amat beracun telah berhasil diambil dari mulut seekor komodo di Kebun Binatang Singapura, dan meyakinkan para peneliti akan kandungan bisa yang dipunyai komodo.

Di samping mengandung bisa, air liur komodo juga memiliki aneka bakteri mematikan di dalamnya; lebih dari 28 bakteri Gram-negatif dan 29 Gram-positif telah diisolasi dari air liur ini. Bakteri-bakteri tersebut menyebabkan septikemia pada korbannya; jika gigitan komodo tidak langsung membunuh mangsa dan mangsa itu dapat melarikan diri, umumnya mangsa yang sial ini akan mati dalam waktu satu minggu akibat infeksi. Bakteri yang paling mematikan di air liur komodo agaknya adalah bakteri Pasteurella multocida yang sangat mematikan; diketahui melalui percobaan dengan tikus laboratorium. Karena komodo nampaknya kebal terhadap mikrobanya sendiri, banyak penelitian dilakukan untuk mencari molekul antibakteri dengan harapan dapat digunakan untuk pengobatan manusia.

Reproduksi

Musim kawin terjadi antara bulan Mei dan Agustus, dan telur komodo diletakkan pada bulan September. Selama periode ini, komodo jantan bertempur untuk mempertahankan betina dan teritorinya dengan cara "bergulat" dengan jantan lainnya sambil berdiri di atas kaki belakangnya. Komodo yang kalah akan terjatuh dan "terkunci" ke tanah. Kedua komodo jantan itu dapat muntah atau buang air besar ketika bersiap untuk bertempur. Pemenang pertarungan akan menjentikkan lidah panjangnya pada tubuh si betina untuk melihat penerimaan sang betina. Komodo betina bersifat antagonis dan melawan dengan gigi dan cakar mereka selama awal fase berpasangan. Selanjutnya, jantan harus sepenuhnya mengendalikan betina selama bersetubuh agar tidak terluka. Perilaku lain yang diperlihatkan selama proses ini adalah jantan menggosokkan dagu mereka pada si betina, garukan keras di atas punggung dan menjilat. Kopulasi terjadi ketika jantan memasukan salah satu hemipenisnya ke kloaka betina. Komodo dapat bersifat monogamus dan membentuk "pasangan," suatu sifat yang langka untuk kadal.

Betina akan meletakkan telurnya di lubang tanah, mengorek tebing bukit atau gundukan sarang burung gosong berkaki-jingga yang telah ditinggalkan. Komodo lebih suka menyimpan telur-telurnya di sarang yang telah ditinggalkan. Sebuah sarang komodo rata-rata berisi 20 telur yang akan menetas setelah 7–8 bulan. Betina berbaring di atas telur-telur itu untuk mengerami dan melindunginya sampai menetas di sekitar bulan April, pada akhir musim hujan ketika terdapat sangat banyak serangga.

Proses penetasan adalah usaha melelahkan untuk anak komodo, yang keluar dari cangkang telur setelah menyobeknya dengan gigi telur yang akan tanggal setelah pekerjaan berat ini selesai. Setelah berhasil menyobek kulit telur, bayi komodo dapat berbaring di cangkang telur mereka untuk beberapa jam sebelum memulai menggali keluar sarang mereka. Ketika menetas, bayi-bayi ini tak seberapa berdaya dan dapat dimangsa oleh predator.

Komodo muda menghabiskan tahun-tahun pertamanya di atas pohon, tempat mereka relatif aman dari predator, termasuk dari komodo dewasa yang kanibal, yang sekitar 10% dari makanannya adalah biawak-biawak muda yang berhasil diburu. Komodo membutuhkan tiga sampai lima tahun untuk menjadi dewasa, dan dapat hidup lebih dari 50 tahun.

Di samping proses reproduksi yang normal, terdapat beberapa contoh kasus komodo betina menghasilkan anak tanpa kehadiran pejantan (partenogenesis), fenomena yang juga diketahui muncul pada beberapa spesies reptil lainnya seperti pada Cnemidophorus.

Partenogenesis

Sungai, seekor komodo di Kebun Binatang London, telah bertelur pada awal tahun 2006 setelah dipisah dari jantan selama lebih dari dua tahun. Ilmuwan pada awalnya mengira bahwa komodo ini dapat menyimpan sperma beberapa lama hasil dari perkawinan dengan komodo jantan di waktu sebelumnya, suatu adaptasi yang dikenal dengan istilah superfekundasi.

Pada tanggal 20 Desember 2006, dilaporkan bahwa Flora, komodo yang hidup di Kebun Binatang Chester, Inggris adalah komodo kedua yang diketahui menghasilkan telur tanpa fertilisasi (pembuahan dari perkawinan): ia mengeluarkan 11 telur, dan 7 di antaranya berhasil menetas. Peneliti dari Universitas Liverpool di Inggris utara melakukan tes genetika pada tiga telur yang gagal menetas setelah dipindah ke inkubator, dan terbukti bahwa Flora tidak memiliki kontak fisik dengan komodo jantan. Setelah temuan yang mengejutkan ini, pengujian lalu dilakukan terhadap telur-telur Sungai dan mendapatkan bahwa telur-telur itupun dihasilkan tanpa pembuahan dari luar.

Bayi komodo partenogenetik di Kebun Binatang Chester, Inggris.

Komodo memiliki sistem penentuan seks kromosomal ZW, bukan sistem penentuan seks XY. Keturunan Flora yang berkelamin jantan, menunjukkan terjadinya beberapa hal. Yalah bahwa telur Flora yang tidak dibuahi bersifat haploid pada mulanya dan kemudian menggandakan kromosomnya sendiri menjadi diploid; dan bahwa ia tidak menghasilkan telur diploid, sebagaimana bisa terjadi jika salah satu proses pembelahan-reduksi meiosis pada ovariumnya gagal. Ketika komodo betina (memiliki kromosom seks ZW) menghasilkan anak dengan cara ini, ia mewariskan hanya salah satu dari pasangan-pasangan kromosom yang dipunyainya, termasuk satu dari dua kromosom seksnya. Satu set kromosom tunggal ini kemudian diduplikasi dalam telur, yang berkembang secara partenogenetika. Telur yang menerima kromosom Z akan menjadi ZZ (jantan); dan yang menerima kromosom W akan menjadi WW dan gagal untuk berkembang.

Diduga bahwa adaptasi reproduktif semacam ini memungkinkan seekor hewan betina memasuki sebuah relung ekologi yang terisolasi (seperti halnya pulau) dan dengan cara partenogenesis kemudian menghasilkan keturunan jantan. Melalui perkawinan dengan anaknya itu di saat yang berikutnya hewan-hewan ini dapat membentuk populasi yang bereproduksi secara seksual, karena dapat menghasilkan keturunan jantan dan betina. Meskipun adaptasi ini bersifat menguntungkan, kebun binatang perlu waspada kerena partenogenesis mungkin dapat mengurangi keragaman genetika.

Pada 31 Januari 2008, Kebun Binatang Sedgwick County di Wichita, Kansas menjadi kebun binatang yang pertama kali mendokumentasi partenogenesis pada komodo di Amerika. Kebun binatang ini memiliki dua komodo betina dewasa, yang salah satu di antaranya menghasilkan 17 butir telur pada 19-20 Mei 2007. Hanya dua telur yang diinkubasi dan ditetaskan karena persoalan ketersediaan ruang; yang pertama menetas pada 31 Januari 2008, diikuti oleh yang kedua pada 1 Februari. Kedua anak komodo itu berkelamin jantan.

Evolusi

Perkembangan evolusi komodo dimulai dengan marga Varanus, yang muncul di Asia sekitar 40 juta tahun yang silam dan lalu bermigrasi ke Australia. Sekitar 15 juta tahun yang lalu, pertemuan lempeng benua Australia dan Asia Tenggara memungkinkan para biawak bergerak menuju wilayah yang dikenal sebagai Indonesia sekarang. Komodo diyakini berevolusi dari nenek-moyang Australianya pada sekitar 4 juta tahun yang lampau, dan meluaskan wilayah persebarannya ke timur hingga sejauh Timor. Perubahan-perubahan tinggi muka laut semenjak zaman Es telah menjadikan agihan komodo terbatas pada wilayah sebarannya yang sekarang.

Statue of Liberty

The Statue of Liberty (Liberty Enlightening the World [French: La Liberté éclairant le monde]) is a colossal neoclassical sculpture on Liberty Island in New York Harbor, designed by Frédéric Bartholdi and dedicated on October 28, 1886. The statue, a gift to the United States from the people of France, is of a robed female figure representing Libertas, the Roman goddess of freedom, who bears a torch and a tabula ansata (a tablet evoking the law) upon which is inscribed the date of the American Declaration of Independence. A broken chain lies at her feet. The statue has become an iconic symbol of freedom and of the United States.

Bartholdi was inspired by French law professor and politician Édouard René de Laboulaye, who commented in 1865 that any monument raised to American independence would properly be a joint project of the French and American peoples. Due to the troubled political situation in France, work on the statue did not commence until the early 1870s. In 1875, Laboulaye proposed that the French finance the statue and the Americans provide the pedestal and the site. Bartholdi completed both the head and the torch-bearing arm before the statue was fully designed, and these pieces were exhibited for publicity at international expositions. The arm was displayed in New York's Madison Square Park from 1876 to 1882. Fundraising proved difficult, especially for the Americans, and by 1885 work on the pedestal was threatened due to lack of funds. Publisher Joseph Pulitzer of the World initiated a drive for donations to complete the project, and the campaign inspired over 120,000 contributors, most of whom gave less than a dollar. The statue was constructed in France, shipped overseas in crates, and assembled on the completed pedestal on what was then called Bedloe's Island. The statue's completion was marked by New York's first ticker-tape parade and a dedication ceremony presided over by President Grover Cleveland.

The statue was administered by the United States Lighthouse Board until 1901 and then by the Department of War; since 1933 it has been maintained by the National Park Service. The statue was closed for renovation for much of 1938. In the early 1980s, it was found to have deteriorated to such an extent that a major restoration was required. While the statue was closed from 1984 to 1986, the torch and a large part of the internal structure were replaced. After the September 11 attacks in 2001, it was closed for reasons of safety and security; the pedestal reopened in 2004 and the statue in 2009, with limits on the number of visitors allowed to ascend to the crown. The statue is scheduled to close for up to a year beginning in late 2011 so that a secondary staircase can be installed. Public access to the balcony surrounding the torch has been barred for safety reasons since 1916.

Design And Construction

Origin

The origin of the Statue of Liberty project is generally traced to a comment made by French law professor and politician Édouard René de Laboulaye in mid-1865. In after-dinner conversation at his home near Versailles, Laboulaye, an ardent supporter of the Union in the American Civil War, stated, "If a monument should rise in the United States, as a memorial to their independence, I should think it only natural if it were built by united effort—a common work of both our nations." Laboulaye's comment was not intended as a proposal, but it inspired a young sculptor, Frédéric Bartholdi, who was present at the dinner. Given the repressive nature of the regime of Napoleon III, Bartholdi took no immediate action on the idea except to discuss it with Laboulaye. Instead, Bartholdi approached Ismail Pasha, Khedive of Egypt, with a plan to build a huge lighthouse in the form of an ancient Egyptian female fellah or peasant, robed and holding a torch aloft, at the northern entrance to the Suez Canal. Sketches and models were made of the proposed work, though it was never erected. There was a classical precedent for the Suez proposal, the Colossus of Rhodes: a bronze statue of the Greek god of the sun, Helios. This statue is believed to have been over 100 feet (30 m) high, and it similarly stood at a harbor entrance and carried a light to guide ships. The American project was further delayed by the Franco-Prussian War, in which Bartholdi served as a major of militia. In the war, Napoleon III was captured and deposed. Bartholdi's home province of Alsace was lost to the Prussians, and a more liberal republic was installed in France. As Bartholdi had been planning a trip to the United States, he and Laboulaye decided the time was right to discuss the idea with influential Americans. In June 1871, Bartholdi crossed the Atlantic, with letters of introduction signed by Laboulaye. Arriving at New York Harbor, Bartholdi fixed on Bedloe's Island as a site for the statue, struck by the fact that vessels arriving in New York had to sail past it. He was delighted to learn that the island was owned by the United States government—it had been ceded by the New York State Legislature in 1800 for harbor defense. It was thus, as he put it in a letter to Laboulaye, "land common to all the states." As well as meeting many influential New Yorkers, Bartholdi visited President Ulysses S. Grant, who assured him that it would not be difficult to obtain the site for the statue. Bartholdi crossed the United States twice by rail, and met many Americans whom he felt would be sympathetic to the project. However, he remained concerned that popular opinion on both sides of the Atlantic was insufficiently supportive of the proposal, and he and Laboulaye decided to wait before mounting a public campaign. Bartholdi had made a first model of his concept in 1870. The son of a friend of Bartholdi's, American artist John La Farge, later maintained that Bartholdi made the first sketches for the statue during his U.S. visit at La Farge's Rhode Island studio. Bartholdi continued to develop the concept following his return to France. He also worked on a number of sculptures designed to bolster French patriotism after the defeat by the Prussians. One of these was the Lion of Belfort, a monumental sculpture carved in sandstone below the fortress of Belfort, which during the war had resisted a Prussian siege for over three months. The defiant lion, 73 feet (22 m) long and half that in height, displays an emotional quality characteristic of Romanticism, which Bartholdi would later bring to the Statue of Liberty.

Design , Style , And Symbolism

Bartholdi and Laboulaye considered how best to express the idea of American liberty. In early American history, two female figures were frequently used as cultural symbols of the nation. One, Columbia, was seen as an embodiment of the United States in the manner that Britannia was identified with the United Kingdom and Marianne came to represent France. Columbia had supplanted the earlier figure of an Indian princess, which had come to be regarded as uncivilized and derogatory toward Americans. The other significant female icon in American culture was a representation of Liberty, derived from Libertas, the goddess of freedom widely worshipped in ancient Rome, especially among emancipated slaves. A Liberty figure adorned most American coins of the time, and representations of Liberty appeared in popular and civic art, including Thomas Crawford's Statue of Freedom (1863) atop the dome of the United States Capitol Building. The figure of Liberty was also depicted on the Great Seal of France.

Artists of the 18th and 19th centuries striving to evoke republican ideals commonly used representations of Liberty. However, Bartholdi and Laboulaye avoided an image of revolutionary liberty such as that depicted in Eugène Delacroix's famed Liberty Leading the People (1830). In this painting, which commemorates France's Revolution of 1830, Liberty leads an armed mob over the bodies of the fallen. Laboulaye had no sympathy for revolution, and so Bartholdi's figure would be fully dressed in flowing robes. Instead of the impression of violence in the Delacroix work, Bartholdi wished to give the statue a peaceful appearance and chose a torch, representing progress, for the figure to bear.

Crawford's statue was designed in the early 1850s. It was originally to be crowned with a pileus, the cap given to emancipated slaves in ancient Rome. Secretary of War Jefferson Davis, a Southerner who would later serve as president of the Confederate States of America, was concerned that the pileus would be taken as an abolitionist symbol. He ordered that it be changed to a helmet. Delacroix's figure wears a pileus, and Bartholdi at first considered placing one on his figure as well. Instead, he used a diadem, or crown, to top its head. In so doing, he avoided a reference to Marianne, who invariably wears a pileus. The seven rays form a halo or aureole. They evoke the sun, the seven seas, and the seven continents, and represent another means, besides the torch, whereby Liberty enlightens the world.

Bartholdi's early models were all similar in concept: a female figure in neoclassical style representing liberty, wearing a stola and pella (gown and cloak, common in depictions of Roman goddesses) and holding a torch aloft. The face was modeled after that of Charlotte Beysser Bartholdi, the sculptor's mother. He designed the figure with a strong, uncomplicated silhouette, which would be set off well by its dramatic harbor placement and allow passengers on vessels entering New York Bay to experience a changing perspective on the statue as they proceeded toward Manhattan. He gave it bold classical contours and applied simplified modeling, reflecting the huge scale of the project and its solemn purpose. Bartholdi wrote of his technique:

Thomas Crawford's Statue of Freedom

The surfaces should be broad and simple, defined by a bold and clear design, accentuated in the important places. The enlargement of the details or their multiplicity is to be feared. By exaggerating the forms, in order to render them more clearly visible, or by enriching them with details, we would destroy the proportion of the work. Finally, the model, like the design, should have a summarized character, such as one would give to a rapid sketch. Only it is necessary that this character should be the product of volition and study, and that the artist, concentrating his knowledge, should find the form and the line in its greatest simplicity.

Aside from the change in the statue's headgear, there were other design alterations as the project evolved. Bartholdi considered having Liberty hold a broken chain, but decided this would be too divisive in the days after the Civil War. The erected statue does rise over a broken chain, half-hidden by her robes and difficult to see from the ground. Bartholdi was initially uncertain of what to place in Liberty's left hand; he settled on a tabula ansata, a keystone-shaped tablet used to evoke the concept of law. Though Bartholdi greatly admired the United States Constitution, he chose to inscribe "JULY IV MDCCLXXVI" on the tablet, thus associating the date of the country's Declaration of Independence with the concept of liberty.

Consultations with the metalwork foundry Gaget, Gauthier & Co. led Bartholdi to conclude that the skin should be made of copper sheets, beaten to shape by the repoussé method. An advantage of this choice was that the entire statue would be light for its volume—the copper need be only .094 inches (2.4 mm) thick. He decided on a height of 151 feet (46 m) for the statue, double that of Italy's Colosso di San Carlo Borromeo and the German statue of Arminius, both made with the same method. Bartholdi interested a former teacher of his, architect Eugène Viollet-le-Duc, in the project. Viollet-le-Duc planned to construct a brick pier within the statue, to which the skin would be anchored.

Announcement And Early Work

In 1875, France was enjoying improved political stability and a recovering postwar economy. Growing interest in the upcoming Centennial Exhibition in Philadelphia led Laboulaye to decide it was time to seek public support. In September 1875, he announced the project and the formation of the Franco-American Union as its fundraising arm. With the announcement, the statue was given a name, Liberty Enlightening the World. The French would finance the statue; Americans would be expected to pay for the pedestal. The announcement provoked a generally favorable reaction in France, though many Frenchmen resented the United States for not coming to their aid during the war with Prussia. French monarchists opposed the statue, if for no other reason than it was proposed by the liberal Laboulaye, who had recently been elected a senator for life. Laboulaye arranged events designed to appeal to the rich and powerful, including a special performance at the Paris Opera on April 25, 1876, that featured a new cantata by composer Charles Gounod. The piece was titled La Liberté éclairant le monde, the French version of the statue's announced name.

Stereoscopic image of right arm and torch of the Statue of Liberty, 1876 Centennial Exposition

Despite its initial focus on the elites, the Union was successful in raising funds from across French society. Schoolchildren and ordinary citizens gave, as did 181 French municipalities. Laboulaye's political allies supported the call, as did descendants of the French contingent in the American Revolutionary War. Less idealistically, contributions came from those who hoped for American support in the French attempt to build the Panama Canal. The firm of Japy Frères, copper merchants, donated all the copper needed to build the statue, a gift valued at 64,000 francs (about $16,000 at the time or the equivalent of $323,000 today). The copper is said to have come from a mine in Visnes, Norway, though this has not been conclusively determined.

Although plans for the statue had not been finalized, Bartholdi moved forward with fabrication of the right arm, bearing the torch, and the head. Work began at the Gaget, Gauthier & Co. workshop. In May 1876, Bartholdi traveled to the United States as a member of a French delegation to the Centennial Exhibition, and arranged for a huge painting of the statue to be shown in New York as part of the Centennial festivities. The arm did not arrive in Philadelphia until August; because of its late arrival, it was not listed in the exhibition catalogue, and while some reports correctly identified the work, others called it the "Colossal Arm" or "Bartholdi Electric Light". The exhibition grounds contained a number of monumental artworks to compete for fairgoers' interest, including an outsized fountain designed by Bartholdi. Nevertheless, the arm proved popular in the exhibition's waning days, and visitors would climb up to the balcony of the torch to view the fairgrounds. After the exhibition closed, the arm was transported to New York, where it remained on display in Madison Square Park for several years before it was returned to France to join the rest of the statue.

During his second trip to the United States, Bartholdi addressed a number of groups about the project, and urged the formation of American committees of the Franco-American Union. Committees to raise money to pay for the foundation and pedestal were formed in New York, Boston, and Philadelphia. The New York group eventually took on most of the responsibility for American fundraising and is often referred to as the "American Committee". One of its members was 19-year-old Theodore Roosevelt, the future governor of New York and president of the United States. On March 3, 1877, on his final full day in office, President Grant signed a joint resolution that authorized the President to accept the statue when it was presented by France and to select a site for it. President Rutherford B. Hayes, who took office the following day, selected the Bedloe's Island site that Bartholdi had proposed.

Construction in France

On his return to Paris in 1877, Bartholdi concentrated on completing the head, which was exhibited at the 1878 Paris World's Fair. Fundraising continued, with models of the statue put on sale. Tickets to view the construction activity at the Gaget, Gauthier & Co. workshop were also offered. The French government authorized a lottery; among the prizes were valuable silver plate and a terracotta model of the statue. By the end of 1879, about 250,000 francs had been raised.

The head and arm had been built with assistance from Viollet-le-Duc, who fell ill in 1879. He soon died, leaving no indication of how he intended to transition from the copper skin to his proposed masonry pier. The following year, Bartholdi was able to obtain the services of the innovative designer and builder Alexandre-Gustave Eiffel. Eiffel and his structural engineer, Maurice Koechlin, decided to abandon the pier and instead build an iron truss tower. Eiffel opted not to use a completely rigid structure, which would force stresses to accumulate in the skin and lead eventually to cracking. To enable the statue to move slightly in the winds of New York Harbor and as the metal expanded on hot summer days, he loosely connected the support structure to the skin using an armature—a metal framework that ends in a mesh of metal straps, known as "saddles", that are riveted to the skin, providing firm support. In a labor-intensive process, each saddle had to be crafted individually. To prevent galvanic corrosion between the copper skin and the iron support structure, Eiffel insulated the skin with asbestos impregnated with shellac. The change in structural material from masonry to iron allowed Bartholdi to change his plans for the statue's assembly. He had originally expected to assemble the skin on-site as the masonry pier was built; instead he decided to build the statue in France and have it disassembled and transported to the United States for reassembly in place on Bedloe's Island.

Eiffel's design made the statue one of the earliest examples of curtain wall construction, in which the exterior of the structure is not load bearing, but is instead supported by an interior framework. He included two interior spiral staircases, to make it easier for visitors to reach the observation point in the crown. Access to an observation platform surrounding the torch was also provided, but the narrowness of the arm allowed for only a single ladder, 40 feet (12 m) long. As the pylon tower arose, Eiffel and Bartholdi coordinated their work carefully so that completed segments of skin would fit exactly on the support structure.

In a symbolic act, the first rivet placed into the skin, fixing a copper plate onto the statue's big toe, was driven by United States Ambassador to France Levi P. Morton. The skin was not, however, crafted in exact sequence from low to high; work proceeded on a number of segments simultaneously in a manner often confusing to visitors. Some work was performed by contractors—one of the fingers was made to Bartholdi's exacting specifications by a coppersmith in the southern French town of Montauban. By 1882, the statue was complete up to the waist, an event Barthodi celebrated by inviting reporters to lunch on a platform built within the statue. Laboulaye died in 1883. He was succeeded as chairman of the French committee by Ferdinand de Lesseps, builder of the Suez Canal. The completed statue was formally presented to Ambassador Morton at a ceremony in Paris on July 4, 1884, and de Lesseps announced that the French government had agreed to pay for its transport to New York. The statue remained intact in Paris pending sufficient progress on the pedestal; by January 1885, this had occurred and the statue was disassembled and crated for its ocean voyage.

Specification iPad

Size And Weight

Height : 9.56 inches (242.8 mm)
Width : 7.47 inches (189.7 mm)
Depth : 0.5 inch (13.4 mm)
Weight : 1.5 pounds (0.68 kg) Wi-Fi Model ;
1.6 pounds (0.73 kg) Wi-Fi + 3G Model

Display

• 9.7-inch (diagonal) LED-backlit glossy widescreen Multi-Touch display with IPS Technology
• 1024-by-768-pixel resolution at 132 pixels per inch (ppi)
• Fingerprint-resistant oleophobic coating
• Support for display of multiple languages and characters simultaneously

Capacity

• 16GB , 32GB , or 64GB flash drive

Sensors

• Accelerometer
• Ambient light sensor

Input And Output

• Dock connector port
• 3.5-mm stereo headphone jack
• Built-in speaker
• Microphone
• Micro-SIM card cray (Wi-Fi + 3G Model Only)

Processor

• 1GHz Apple A4 Custom-disgned , high-performance , low-power system-on-a-chip

Location

• Wi-Fi
• Digital Compass
• Assisted GPS (Wi-Fi + 3G Model)
• Cellular (Wi-Fi + 3G Model)

In The Box

• iPad
• Dock Connector to USB Cable
• 10W USB Power Adapter
• Documentation

Battery And Power

• Built-in 25-watt-hour rechargeable lithium-polymer battery
• Up To 10 Hours of surfing the web on Wi-Fi watching video , or listening to music
• Up To 9 Hours of surfing the web using 3G data network
• Charging via power adapter or USB to computer system
  

Symptoms of Esophageal Computer Spyware

If the computer begins to show the following symptoms, can be sure your computer has been in rasuki spyware.
1. Pop-up ads appear every time you connect to the Internet. Some spyware will bombard you with a variety of advertising pop-ups that have nothing to do with the site you're open. Pop ups can be a view porn sites or other junk sites.
2. Computer settings changed, but you can not restore it to its original state. If you see the default home page (or search engine) changes every time restart even if you changed the settings, to be sure spyware has berserang on your computer. Some spyware has the ability to change settings on the internet conection without the user knowing.
3. Internet browsers create additional components that appear at any time without being aware of when you install or download them. Spyware sometimes unite itself with the browser in the form of toolbar components. This section will continue to appear on the browser to the program in the uninstall.
4. Decreased computer performance when in use to run a regular program. Spyware is designed to track your computer activity and displays pop-ups that would drain the resources of your computer. Some spyware can even lead to errors and crashes in Windows suddenly.