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اكتشاف ديناصور مجنح في الصين

Capture d’écran 2015-07-18 à 07.56.04اكتشف العلماء في شمال شرقي الصين حفرية تكاد تكون كاملة في حال حفظ ممتازة لديناصور ذي ريش وأجنحة تحاكي الطيور، لكن العلماء يساورهم الشك في مدى قدرة هذا المخلوق العجيب على الطيران.

وقال الباحثون أمس (الخميس) إن هذا الكائن آكل اللحوم السريع الجري يبلغ طوله نحو 1.8 متر ويغطي معظم أجزاء جسمه شعر بسيط شبيه بالريش مع وجود ذيل طويل وريش طويل على جناحيه.

وهذا المخلوق أضخم ديناصور مجنح معروف عاش منذ 125 مليون عام إبان العصر الطباشيري (الكريتاسي). ونظراً الى فمه المملوء بالأسنان الحادة وغرابة منظره العام فقد وصف ستيف بروسات عالم الاحياء القديمة بجامعة ادنبره هذا الديناصور – واسمه العلمي (جينيوانلونغ سوناي)- بأنه “كائن أزغب كثيف الشعر من الجحيم”.

وينتمي هذا المخلوق الى مجموعة من الديناصورات المفترسة التي تتغذى على لحوم الطيور وتمت بصلة وثيقة لها – وهو من أبناء عمومة الديناصور “فيلوسيرابتور” الذي ظهر بصورة تفتقر إلى الدقة العلمية في سلسلة أفلام “حديقة الديناصورات”، إذ بدا أضخم كثيراً من حجمه الحقيقي – على رغم أنه عاش بعد تلك الحقبة بنحو 40 الى 50 مليون سنة.

وقال بروسات الذي تعاون مع عالم الأحياء العتيقة الصيني جون تشانغ لو “جينيوانلونغ ديناصور شبيه بالطيور في حقيقة الأمر، ولن تفكر في أنه يختلف كثيراً عن الديك الرومي (الحبشي) أو حيوان الايمو أو دجاجة ضخمة الحجم”.

ويشبه جناحاه في الشكل والهيئة جناحي طائر حديث على غرار النسر أو العقاب.

وصرح بروسات بأنه “لو شاهدت هذا الجناح على حدة فلربما ظننت أن بمقدور جينيوانلونغ الطيران، لكنه كان من المفترسات الضخمة للطيور وكان ساعداه أقصر كثيراً بالنسبة إلى حجم جسمه لدرجة أنني فكرت ملياً ظناً مني أنه يستطيع الطيران أو الانزلاق أو أن يفعل أي شيء في الهواء”.

وأضاف ان من المرجح ان “جينيوانلونغ” كان يستخدم جناحيه بغرض الخيلاء على نفس المنوال الذي تنتهجه أنثى الطاووس في استعراض ونفش ريش الذيل لاجتذاب الذكور ناهيك عن إخافة المنافسين. وثمة احتمال آخر هو استخدام الجناحين لاحتضان البيض في العش، مشيراً إلى أن اكتشاف ديناصور بمواصفات “جينيوانلونغ” يثير علامات استفهام عن سبب نشوء هذه الأجنحة أصلاً. ونشر هذا البحث في دورية (ساينتيفيك ريبورتس).

وقال بروسات: “هل نشأت الأجنحة خصوصاً من أجل الطيران؟ وفي هذه الحال ربما يكون جينيوانلونغ انحدر من نسل أسلاف قادرة على الطيران لذا فقد ظل يحتفظ بأجنحة. وبدلاً من ذلك هل نشأت هذه الأجنحة بادئ ذي بدء بغرض الاستعراض أو لاحتضان البيض أو لوظائف أخرى؟ ثم انها تحورت في بعض الديناصورات بعينها الى جنيحات للانزلاق أو الطيران”.

وتطورت الطيور من أسلاف من الديناصورات الصغيرة المجنحة، وعاش أقدم طائر معروف وهو “الأركيوبتركس” الذي كان في حجم الغراب منذ نحو 150 مليون سنة.

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