Fossils of Megalograptus were first described by Samuel Almond Miller in 1874. Miller mistakenly believed the fossil material, consisting of a postabdominal (segments 8–12) tergite and two fragments of an appendage, was the integument of a graptolite (a member of Graptolithina, an extinct group of colonial pterobranchs),[3] and gave it the name Megalograptus, meaning "great writing" (deriving from the Greek megale, "great", and graptos, "writing", commonly used for graptolite fossils).[6] One reason for Miller's mistaken identification is that the exact outline of the fossils was unclear because they were not properly cleaned yet.[7] The fragmentary fossils of M. welchi were initially recovered by L. B. Welch, whom the species name welchi honours, near Liberty, Ohio,[3] in rocks of Katian (Late Ordovician) age[2] of the Elkhorn Formation.[3] With the exception of the type material, M. welchi is only fragmentarily known. It is probable that more fossils could have been uncovered if it had been immediately recognized as a large eurypterid. By the time it was recognized as such and the fossils were deemed to be of interest, further work at the fossil site had irreversibly damaged what remained of the eurypterid fossils.[3][7] The status of Megalograptus as a graptolite was first questioned in 1908 by Rudolf Ruedemann, who was researching Ordovician graptolites. Ruedemann instead recognized the remains of M. welchi as eurypterid fossils.[3] That same year, Ruedemann's suspicions were confirmed in discussions with August Foerste and Edward Oscar Ulrich, who also agreed that the fossils were of a eurypterid.[3][7] Foerste was invited to contribute with his understanding of Megalograptus to Ruedemann's and John Mason Clarke's 1912 monograph The Eurypterida of New York.[3] He recognized Megalograptus as similar to the eurypterid Echinognathus clevelandi, assuming them to either be related or of the same genus. The features uniting the two were noted to be the spines of the appendages, the scaly ornamentation and the longitudinal ridges of the preserved segment. Foerste also noted that the fossils of M. welchi were not morphologically distinct enough from other eurypterids to differentiate it, with its earlier age instead serving as the main distinction of the genus and species.[7] Additional fossils Fossil type material of Megalograptus alveolatus The fragmentary fossil type material of M. alveolatus, originally assigned to the genus Ctenopterus Megalograptus was considerably revised in 1955 by Caster and Kjellesvig-Waering in Leif Størmer's 1955 Treatise on Invertebrate Paleontology, from which the modern understanding of the genus originates. The revision was made possible with the discovery of new fossil material, consisting of what at the time was the best preserved Ordovician eurypterid fossil material discovered.[3] These fossils, found in deposits of Katian age[2] alongside the Ohio River road (U.S. Route 52), approximately 14.5 kilometres (9.0 mi) north of Manchester, Ohio, were assigned to a new species, M. ohioensis. The type material of M. welchi was compared to the new fossils by Caster and Kjellesvig-Waering, though only in the "walking legs" (i.e. the second to fifth pair of appendages) given that they were the only body part preserved for both M. welchi and M. ohioensis. While recognized as being of the same genus, Caster and Kjellesvig-Waering also noted differences, supporting the species distinction of M. welchi and M. ohioensis, including the leg of M. welchi being stouter, with thicker and shorter spines, and some differences in the joints (in M. welchi, the second joint had spines, which it did not in M. ohioensis, and in M. welchi, the spine-shaped ultimate joint was blunt and thick, whereas it was slender in M. ohioensis).[3] In 1964, Caster and Kjellesvig-Waering named two new species of Megalograptus[3] based on additional fossil material from the Katian[2] of Ohio: M. shideleri and M. williamsae. M. shideleri was named based on fragmentary fossil specimens originally found by William H. Shideler in the Saluda Formation near Oxford, Ohio, and in Indiana. The species is named in his honor. M. shideleri differs from M. ohioensis in that its gnathobases have fewer denticles and a much more developed second tooth. The M. shideleri fossils could not be compared to the type material of M. welchi as there is no overlap in the preserved body parts. M. williamsae was named based on a cercal blade, alongside fragments of tergites and appendages, discovered in the Waynesville Formation, near Clarksville, Ohio, by Carrie Williams, whom the species name honours. M. williamsae differs from M. ohioensis in its cercal blades, with a slightly different pattern of scales and longer, narrower and sharper end points, rather than the more acute, hooked and stouter end points in M. ohioensis.[3] The species M. alveolatus was originally named as a species of the very distantly related Ctenopterus by Ellis W. Shuler in 1915, based on fossil fragments, including of the appendages and the telson spike,[8] collected in Late Ordovician[2] deposits along Walker Mountain in Virginia[8] belonging to the Bays Formation.[9] It was the first eurypterid to be described from Virginia.[10] The species name alveolatus refers to the pronounced development of the alveolar processes (pits) around the spines.[8] Because of the fragmentary state of its fossils, M. alveolatus has had a complex taxonomic history. Although Kjellesvig-Waering initially believed that it might have been a species of Mixopterus, tentatively designating it as "Mixopterus (?) alveolatus",[10] Caster and Kjellesvig-Waering assigned the species to Megalograptus in 1964, arguing that the morphology of the appendage described by Shuler in 1915 demonstrated that the fossils undoubtedly belonged to Megalograptus. M. alveolatus was kept as a distinct species on account of the third joint of the appendage being proportionally larger than the same joint in M. ohioensis.[3] In addition to the five described species assigned to the genus, there may be as many as four distinct undescribed species of Megalograptus. Caster and Kjellesvig-Waering noted in 1964 that there were very fragmentary eurypterid fossils[3] known from the Katian-age[2] deposits of the Whitewater Formation near Oxford, Ohio, referring these specimens to Megalograptus.[3] In 2002, fossils belonging to a small variety of Megalograptus were first reported from Katian-age deposits of the Nicolet River Formation in Quebec, Canada.[2][11][12] Megalograptus fossils found in Katian-age deposits in the US state of Georgia and in the Shawangunk Ridge of New York may also represent two distinct new species.[2][12] Additionally, fossils potentially referrable to Megalograptus have been reported from the Martinsburg Formation of New York and Pennsylvania.[13] Classification Schematic reconstruction of Megalograptus ohioensis Schematic reconstruction of Pentecopterus decorahensis M. ohioensis (left) compared to the earliest and basalmost known member of the Megalograptidae, Pentecopterus decorahensis (right) Shortly after being recognized as a eurypterid in the early 20th century, Megalograptus was noted by Foerste in 1912 as being similar, and likely closely related, to the genus Echinognathus.[7] In 1934, Størmer classified Megalograptus and Echinognathus, together with the genera Mixopterus and Carcinosoma, into the family Carcinosomatidae. The taxonomy was amended by Erik N. Kjellesvig-Waering in 1955, who transferred Mixopterus to its own family, the Mixopteridae, and placed Megalograptus and Echinognathus in their own family, the Megalograptidae.[14] The Megalograptidae has traditionally been interpreted as closely related to the Mixopteridae.[15] In 1964, Caster and Kjellesvig-Waering placed Megalograptidae, alongside Mixopteridae, Carcinosomatidae and Mycteroptidae, into the superfamily Mixopteracea (later renamed to Mixopteroidea).[3] In 1989, Victor P. Tollerton, perceiving them to be distinct enough, placed the Megalograptidae into their own superfamily, the Megalograptoidea.[16] In 2004, O. Erik Tetlie determined Megalograptus, and by extension the Megalograptidae, to be taxonomically problematic, perceiving the genus to share several potential synapomorphies (derived, "advanced", traits unique to a clade) with both the Eurypteroidea and the Mixopteroidea (now considered a synonym of Carcinosomatoidea), as well as having a large number of apomorphies (characteristics different from what existed in the ancestor of an organism). Depending on how the analysis was conducted, Megalograptus changed position in the phylogenetic tree, only sometimes being recovered as basal within the Mixopteroidea (if taxa where less than one third of the body was preserved were removed). Tetlie speculated that Megalograptus and its family could be very basal, given their early age,[15] retaining Megalograptoidea as a distinct superfamily, though with a highly uncertain phylogenetic position, either very basal, between the Onychopterelloidea and the Eurypteroidea, or more derived, between the Eurypteroidea and the Mixopteroidea.[12] No phylogenetic analysis ever recovered Megalograptus in these positions and the genus was often excluded from analyses due to its perceived strange mix of features.[1] The description of Pentecopterus, the only other genus in the Megalograptidae, in 2015 by Lamsdell and colleagues saw the megalograptids again considered to be close relatives of the mixopterids and carcinosomatids. The phylogenetic analysis accompanying the description of the new genus resolved the Megalograptidae as basal within the relatively derived Carcinosomatoidea superfamily, which also includes the Carcinosomatidae and Mixopteridae. The cladogram below is simplified from the study by Lamsdell et al. (2015), collapsed to only display the Carcinosomatoidea.[1] Carcinosomatoidea   Megalograptidae   Pentecopterus decorahensis       Echinognathus clevelandi       Megalograptus williamsae       Megalograptus ohioensis     Megalograptus welchi             Mixopteridae   Lanarkopterus dolichoschelus       Mixopterus kiaeri     Mixopterus multispinosus       Carcinosomatidae   Holmipterus suecicus     Rhinocarcinosoma vaningeni         Carcinosoma newlini     Carcinosoma libertyi         Eusarcana acrocephalus     Eusarcana scorpionis               OQJN6DJZAAXQ9ERRQXB2YXMKGLVKTWC262IGPTDOLX6ZHIOP2JY2RJ4UIRZNO8YVDC9LDDT6ZY3EZD8E63DB উক্রেনের দক্ষিণাঞ্চলীয় শহর জাপোরিঝজিয়ায় ক্ষেপণাস্ত্র হামলায় অন্তত ২৩ জন নিহত হয়েছেন। আহত হয়েছেন ২৮ জন। বেসামরিক গাড়িবহরে ক্ষেপণাস্ত্র হামলায় এ হতাহতের ঘটনা ঘটে। রাশিয়ার এ হামলা চালিয়েছে বলে অভিযোগ করেন এ অঞ্চলের ইউক্রেনীয় গভর্নর ওলেকজান্দার স্তারুখ। খবর রয়টার্স। মনোনয়নপত্র জমা দেয়ার শেষদিনে ভারতীয় কংগ্রেসের সভাপতি নির্বাচনের সমীকরণ বদলে দিলেন রাজ্যসভার বিরোধী দলনেতা মল্লিকার্জুন খড়গে। তার প্রধান প্রতিদ্বন্দ্বী হিসেবে আছেন এতদিন আলোচনায় থাকা প্রবীণ রাজনীতিবিদ শশী থারুর। দুজনই আজ শুক্রবার মনোনয়নপত্র জমা দিলেন। খবর ডিএনএ ইন্ডিয়া। আগামী ১৭ অক্টোবর নির্বাচনের মাধ্যমে দলটির নতুন নেতা পাবে। এর মাধ্যমে দুই যুগ পর গান্ধী পরিবারের বাইরে কেউ কংগ্রেস সভাপতি হতে যাচ্ছেন। মনোনয়ন জমা দেয়ার পর শশী থারুর বলেন, সোনিয়া গান্ধী ও রাহুল গান্ধী আশ্বস্ত করেছেন যে দলের কোন আনুষ্ঠানিক প্রার্থী নেই। নির্বাচনে তারা নিরপেক্ষ থাকবেন। তারা যতটা সম্ভব প্রার্থীকে স্বাগত জানাবেন। তবে ভারতীয় সংবাদমাধ্যমগুলো বলছে, গান্ধী পরিবারের আশীর্বাদ রয়েছে খড়গের দিকে। রাজস্থানের মুখ্যমন্ত্রী অশোক গেহলটের মন্তব্যেও সেটা উঠে এসেছে। নিজ বাসভবনের বাইরে সাংবাদিকদের তিনি বলেন, সব জ্যেষ্ঠ নেতারা একসাথে খড়গের প্রার্থিতা নিয়ে সিদ্ধান্ত নিয়েছেন। এর আগে গেহলট সভাপতি পদের জন্য সবচেয়ে এগিয়ে ছিলেন। কিন্তু শচীন পাইলট মুখ্যমন্ত্রী হলে একদল বিধায়ক পদত্যাগ করার হুমকি দেয়ার পর তিনি মনোনয়ন প্রত্যাহার করেন। কংগ্রেস একটি রাজবংশ-চালিত দল বলে প্রায়শ আক্রমণ করে থাকে প্রতিপক্ষ বিজেপি। আর এবার গান্ধী পরিবারই নির্বাচন থেকে দূরে থাকার সিদ্ধান্ত নিয়েছে। ১৯৯৮ সালে সোনিয়া গান্ধীকে সভাপতি করার জন্য পদত্যাগ করেছিলেন সীতারাম কেশরী। এরপর ২৪ বছর পর অ-গান্ধী সভাপতি পাচ্ছে কংগ্রেস। ভারতের স্বাধীনতা সংগ্রামে উল্লেখযোগ্য ভূমিকা রাখা দলটিতে গান্ধী পরিবারের বাইরে ১১ জন সভাপতি ছিলে একজন প্রত্যক্ষদর্শী সাংবাদিক জানান, শহরটির ওরেখোভো গাড়ি বাজারের মাটিতে বা গাড়ির ভেতরে এখনো মৃতদেহগুলো পড়ে আছে। ক্ষেপণাস্ত্রের আঘাতে বাজারের গাড়ির দুটি লাইনের কাছে একটি গর্ত তৈরি হয়েছে। জাপোরিঝজিয়ায় ইউক্রেনীয় গভর্নর টেলিগ্রামে লিখেছেন, এ পর্যন্ত ২৩ জন নিহত ও ২৮ জন আহত হয়েছে। সবাই বেসামরিক। ক্ষেপণাস্ত্রের বিস্ফোরণে চারদিকে ধ্বংসাবশেষ ছড়িয়ে ছিটিয়ে পড়ে, শার্পনেলের আঘাতে গাড়িগুলো ঝাঁঝড়া হয়ে যায়। বহরের অধিকাংশ গাড়ি ও তিনটি মাইক্রোবাসের জানালা উড়ে যায়। পুলিশ ও জরুরি বিভাগের কর্মীরা হতাহতদের সরিয়ে নিতে ঘটনাস্থলে উপস্থিত হন। রয়টার্স জানিয়েছে, গাড়িগুলো আরোহীদের জিনিসপত্র, কম্বল ও সুইকেসে ভরা ছিল। হলুদ রঙের একটি গাড়ির চালকের আসনে বসা এক ব্যক্তির মৃতদেহ কাত হয়ে যাত্রীর আসনে পড়ে আছে, তার বাম হাত তখনও গাড়ির স্টিয়ারিং হুইল ধরে আছে। নিজেকে নাতালিয়া বলে পরিচয় দেয়া এক নারী জানান, তিনি ও তার স্বামী জাপোরিঝজিয়ায় তাদের শিশুদের দেখতে এসেছিলেন। স্বামীর পাশে দাঁড়িয়ে তিনি বলেন, আমরা আমার মার কাছে ফিরে যাচ্ছিলাম। আমরা বেঁচে গেছি। এটা অলৌকিক।