Брахитрахелопан (Brachytrachelopan, от греч. "короткошеий Пан") — род динозавров, живший 150—145 млн лет назад (титонский ярус позднего юрского периода) на территории нынешней Аргентины. Достигал длины 10 метров, высоты 3 метров и веса 5—7 т. Впервые описали Оливер Раухут, Ремес, Фехнер, Кладера и Пуэрта в 2005 году.

 Характерной чертой брахитрахелопана является крайне короткая шея, состоящая всего из 12 позвонков. Она больше напоминает шею стегозавра, чем диплодоцида. Как и у других членов группы дикреозавров, у него были высокие шипы на стпине и бёдрах, предположительно поддерживавшие какое-то образование, похожее на парус. Шипы к передней части изгибаются вперёд. Это доказывает то, что животное держало голову книзу и питалось с земли. Череп и хвост единственного известного скелета отсутствуют.

 Останки B. mesai обнаружил аргентинский овчар Дэниель Меза, искавший потерявшуюся овцу. Родовое название выбрано в честь этого события (Пан — бог пастухов), видовое — по фамилии пастуха.

 В результате филогенетических анализов, основываясь на синапоморфии, Brachytrachelopan отнесли к семейству Dicraeosauridae надсемейства Diplodocoidea.

 This taxon's very short neck (approximately 40% shorter than other dicraeosaurids and the shortest of any known sauropod) is evidence that this lineage specialized to fill an ecological niche not exploited by other members of this infraorder. Small for a sauropod, Brachytrachelopan measured less than 10 metres (33 ft) in length. Rauhut et al. (2005, 670) note that the high degree of fusion present between the preserved neural arches and their respective centra, as well as fusion between the sacral centra, sacral neural arches, and sacral neural spines is evidence that the holotype does not represent a juvenile animal. Hence, the small body size is not a relic of ontogeny.

 Rauhut et al. (2005, 671-672) note that the tendency towards shorter-necks seen in dicraeosaurids, and most evident in Brachytrachelopan, runs counter to the lengthening of the neck seen most sauropod lineages (brachiosaurids, titanosaurs, diplodocids, etc.) and indicates that this group of sauropods was "progressively adapting for low browsing and might have been specialized on specific food sources, as has been suggested for Amargasaurus and Dicraeosaurus." Moreover, the morphology of the cervical neural arches in Brachytrachelopan would have significantly restricted dorsal flexion of neck and most likely indicates that this sauropod was specialized to a diet of plants "growing at heights of between about 1 and 2 m." Rauhut et al. (2005, 672) also suggest that diet may have been a limiting factor in body size among dicraeosaurids, and that this may have placed them in the same ecological niche as "large low-browsing iguantodontian ornithopods." It is notable that such large iguanodontians are absent from the Late Jurassic Gondwanan sediments that have produced all known fossils of dicraeosaurids, while they are abundant in similar ecosystems of the same age in North America, where dicraeosaurids are absent. This may indicate that large iguanodontians and dicraeosaurids (especially Brachytrachelopan) were ecological analogs, resulting from parallel evolution in two distantly related dinosaurian lineages.

 Dicraeosauridae is a family of sauropod dinosaurs known from the Late Jurassic and Early Cretaceous of Africa and South America. Currently only three genera are recognised; the Jurassic South American genus Brachytrachelopan, the Jurassic African Dicraeosaurus and the South American Early Cretaceous Amargasaurus, with its distinctive neck spines. All three animals are small by sauropod standards, with relatively short necks.

 McIntosh (1990) includes a number of genera within the subfamily Dicraeasaurinae of the family Diplodocidae, but many of these are now recognised as belonging to distinct families (Nemegtosauridae and Rebbachisauridae).

 The group is described cladistically as a stem-based taxon defined as "The most inclusive clade containing Dicraeosaurus hansemanni Janensch 1914 but not Diplodocus longus Marsh 1878" or as "all diplodocoids more closely related to Dicraeosaurus hansemanni than to Diplodocus longus (Sereno 1998 p.63, Upchurch et al. 2004 p.304, Wilson 2005 p.35).

 Репродукции (1, 2, 3, 4, 5, 6, 7):

 Размеры тела в сравнении с человеком и другими дикреозаврами:

 Ископаемые останки:

Tags: Вымершие рептилии, Юра, авеметатарзалии, архозавроморфы, архозавры, диапсиды, дикреозавры, динозавроморфы, динозавры, завроподоморфы, завроподы, ящеротазовые

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