চীনের ইনস্টিটিউট অফ ভার্টেব্রেট প্যালিয়ন্টোলজি অ্যান্ড প্যালিয়্যানথ্রপোলজি (IVPP) এর গবেষকগণ ১২০ মিলিয়ন বছর আগের বিলুপ্ত এক ছোট্ট পাখির আংশিক ফসিল বা জীবশ্মেন সন্ধান পেয়েছেন। পাখিটি তুলনামূলক এতটাই ছোট যে সেটা হাতের মুঠোয় এঁটে যাবে। সংগৃহীত খুলিটি ডাইনোসর এবং পাখির বৈশিষ্ট্যের সংমিশ্রণ।
এই ২ সে.মি জীবাশ্ম খুলিটির সাথে বিশাল আকৃতির Tyrannosaurus rex বা T-rex এর সাথে গাঠনিক ও বৈশিষ্ট্যগত মিল রয়েছে। এটা ইঙ্গিত করে আগের পাখিগুলোর সাথে আদিপুরুষ ডাইনোসরদের অনেক বৈশিষ্ট্যগত মিল রয়েছে। এছাড়াও তাদের খুলির বৈশিষ্ট্যের সাথে বর্তমানের পাখিদের থেকে ডাইনোসরদের সাথে বেশি মিল পাওয়া যায়।
নেচার কমিউনিকেশনস জার্নালে গত ২৩ জুন গবেষণাটি প্রকাশিত হয়।
এই পাখিটি আজ থেকে ১২০ কোটি বছর আগে উত্তর-পূর্ব চীনের লিয়াওনিং প্রদেশের একটি অগভীর হ্রদে আটকে গিয়ে জীবশ্মে পরিণত হয়েছিল।
পাখিদের ফ্যামিলি ট্রি পুনঃবিন্যস্ত করার পর, গবেষকরা দেখান যে, নতুন প্রজাতির পাখির ফসিলটা পাখিদের বিলুপ্ত পরিবার enantiornithines এর অন্তর্ভুক্ত ছিল। ক্রিটেসিয়াস যুগে ডাইনোসরের সময় থেকেই তারা পাখিদের মধ্যে সবচেয়ে বৈচিত্র্যময় পরিবার ছিল এবং সারাবিশ্বেই এদের বিচরণ ছিলো।

ক্রেডিট: Wang Min
জীবিত পাখিদের মধ্যে অনেকটা চতুর্ভুজ আকৃতির খুলির সবচেয়ে বেশি নাড়চড়া যোগ্য অস্থির একটা। আর এই চতুষ্কোণ আকৃতির অস্তি পাখিদের এক অনন্য বৈশিষ্ট্য ‘kinetic skull’ এর জন্য দায়ী। এর এই ‘কাইনেটিক স্কার’ মস্তিষ্ক থেকে উপরের চোয়াকে এবং নীচের চোয়ালকে স্বতন্ত্রভাবে চলতে দেয়।
এক্ষেত্রে “enantiornithine” গুলোর খুলি ডাইনোসরের মতো, বিশেষ করে Tyrannosaurus rex এর সাথে মিল পাওয়া যায়। এদিকে ডাইনোসরের সমকালিন পাখিদের (troodontids এবং dromaeosaurs) খুলিতে কাইনেটিক অস্থি ছিল না। এর পরিবর্তে বদ্ধ অস্থি ছিল, যা নড়াচড়া করতে অক্ষম।
আরও দেখুন: গুগল তৈরী করল মস্তিষ্কের সবচেয়ে বিস্তারিত ছবি!
উক্ত পাখির ফসিলের খুলির দুইপাশের দুটো টেমপোরাল অস্থি জীবিত পাখিদের থেকে অনেক আলাদা। বিলুপ্ত এই নতুন প্রজাতির চোয়ালের পেশী সংযুক্তির জন্য দুটি অস্থি খিলান রয়েছে, যা সরীসৃপ জাতীয় প্রাণী যেমন: লেজার্ড, কুমির এবং ডাইনোসরদের মধ্যে দেখতে পাওয়া যায়। এটা খুলির পেছনের অংশকে বেশ শক্ত-পোক্ত করে এবং হাড়ের অতিরিক্ত নাড়াচাড়া প্রতিরোধ করত।
গবেষণা টিমের প্রধান Dr. Wang Min বলেন, “আমরা যখন খুলির সকল অংশকে আবার জুড়ে হাই রেজ্যুলেশন সিটিস্ক্যানের মাধ্যমে ফসিলের ত্রিমাত্রিক গঠন বের করতে সমর্থ হলাম, তখন আমি একটা নির্দিষ্ট অস্থিতে বেশ সমস্যার সম্মুখীন হলাম।”
এরপর তার সহকারী Dr. Thomas Stidham প্রস্তাব দেন, অস্থিটি pterygoid এবং দেখতে হুবহু Linheraptor ডাইনোসর এর মতো। জীবাশ্মে পরিণত হবার প্রথম দিকের পাখির মধ্যে এই pterygoid অস্থি প্রথম ভালভাবে সংরক্ষিত হয়ে যায়। যার ফলে প্রাচীন পাখিদের pterygoid অস্থির মধ্যে এটিই খুব ভালোভাবে সংরক্ষণ করা গেছে। যেটা আগে সম্ভব হয় নি।
গবেষকরা পাখির খুলির সিটিস্ক্যানের সাথে চিনের মঙ্গোলিয়ার পাওয়া Linheraptor ডাইনোসরের খুলির স্ক্যানের সাথে তুলনা করেন। এর ফলাফলে দেখা যায়, খুলির পেছনের অংশের অনেক বৈশিষ্ট্য, basisphenoid অস্থির ধরনসহ মস্তিষ্কের অন্যান্য অস্থির সাথে যুক্ত বৈশিষ্ট্যের মধ্যে বেশ মিল রয়েছে। পাখিটি জীবাশ্ম জীবিতি পাখিদের থেকে ডাইনোসরের সাথে বেশি মিল সম্পন্ন।
Dr. Wang আরও বলেন, “পাখির শরীরের ডাইনোসরের অস্থি থাকাটা সেই সমকালিন enantiornithines বা অন্যান্য পাখিদের দশ মিলিয়ন বছর আগে ক্রিটেসিয়াস যুগে সারাবিশ্ব সর্বোচ্চ সফলতা থেকে আটকাতে পারেনি।”
গবেষণাপত্র: Cretaceous bird with dinosaur skull sheds light on avian cranial evolution, Nature Communications (2021)
DOI: 10.1038/s41467-021-24147-z
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The Premier League statement read: ‘Premier League fixtures will resume this weekend after a pause to the season as a mark of respect following the passing of Her Majesty Queen Elizabeth II. Jackson looks like he could be a promising young player who’ll one day be good enough to lead the line for Chelsea, but for now they probably do need someone else in that position. I always assumed Chelsea’s 2015 16 season was the worst a “big” club could get in the Premier League. The Blues finished in tenth that year with 50 points. For Chelsea to hit the big five-oh this time, they’ll need to win at least two of their last four matches and draw the other two, which include games against both Manchester clubs and Newcastle. I wouldn’t feel good about that outcome. At the first attempt, Todd Boehly and Clearlake Capital have put together a season worse than any of Roman Abramovich’s 19 years in charge. Yeah, it’s rough. Even Boehly’s natural allies, the data nerds at FBRef, are making fun of him now.
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116 Hampton RoadSouthampton, NY 11968 Ferry services for guests operate between The Dock at The Waterlot at Fairmont Southampton and Albouy’s Point in the heart of the city of Hamilton (weather permitting). Golf clubs bags are permitted on board, but no luggage is allowed. Please refer to your registration package for details and times. Filter Results Viewing Instruction Modes The 26-year old has had a difficult time at Everton over the past two seasons and is ready for a fresh start. Southampton have been pursuing Holgate all summer and want him alongside Nathan Wood. In late 2019, The Fairmont Southampton announced one of the most exciting and large-scale renovation projects in Bermuda history. Facebook: Southampton Maternity Service – postnatal care and discharge
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Similarly, the Supportive Services for Veteran Families (SSVF) Program Office offers rapid housing to Veterans facing homelessness. The rental subsidy arrangement they provide to eligible Veterans is known as a Shallow Subsidy service. Grantees make a two-year commitment to a landlord and household unless their household terminates their housing or receives a permanent rental subsidy. Example 2: A housing provider operates housing that is legally limited to persons with chronic mental illness. The provider may ask applicants for information needed to determine if they have a mental disability that would qualify them for the housing. However, in this circumstance, the provider may not ask applicants if they have other types of physical or mental impairments. If it is not readily apparent that an applicant has a chronic mental disability, the provider may request reliable information documentation of the mental disability needed to qualify for the housing.
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The departing licensee forfeits any pending listings and customers gained while under the broker. All keys and related contracts must be passed back to the broker, and the licensee has one month to transfer their license to the new broker. When a licensee terminates the relationship with their broker, the licensee cannot contact any of the broker’s customers under a listing or management agreement before the contract expires. This means that any pending contracts, listings or buyers remain with the broker not the salesperson. Another fiduciary responsibility of the property manager is to address tenant complaints and concerns quickly and completely. A water leak left untended will inevitably lead to greater damage to the property and potentially to the tenant, if, for example, mold grows as a result of the untended water leak. Such issues could also lead to tenant’s breaking the lease, adding unnecessary inconvenience and cost for both tenant and property owner.