أرسينوي‌ثريوم

(تم التحويل من Arsinoitherium)

أرسينوي‌ثريوم
Arsinoitherium
Temporal range: 36–27 م‌س
أواخر الإيوسين - مطلع الاوليگوسين
أرسينوي‌ثريوم زيتلي
التصنيف العلمي
مملكة:
الحيوانية
Phylum:
الحبليات
Class:
الثدييات
Superorder:
الوحوش الأفريقية Afrotheria
Order:
†Embrithopoda
Family:
†الوحوش الأرسينوية Arsinoitheriidae
Genus:
†Arsinoitherium

بيدنل، 1902
Type species
Arsinoitherium zitteli
بيدنل، 1902
الأنواع
  • A. zitteli بيدنل، 1902
  • A. andrewsi لانكستر، 1903
  • A. giganteus ساندرز، كاپلمان وراسموسن، 2004

أرسينوي‌ثريوم (Arsinoitherium، أي "وحش أرسينوي") هو جنس منقرض من الثدييات paenungulate ذات القربى بالفيلة، الخيلانيات، الوبريات والمدعمات المنقرضة، وكذلك شبيهات الكركدن المنقرضة الأخرى. هذه الأنواع كانت آكلة عشب تشبه الفيلة وقد عاشت في أواخر الإيوسين ومطلع الاوليگوسين في شمال أفريقيا من 36 إلى 30 مليون سنة مضت، في مناطق الغابات المطيرة المدارية وعلى حواف مستنقعات المانگروڤ. وأحد الأحفورات المكتشفة حديثاً، وحش أرسينوي العملاق Arsinoitherium giganteum، عاش في إثيوپيا من نحو 27 مليون سنة مضت.

أصل الاسم

جمجمة أرسينوي‌ثريوم.

اسم الجنس أرسينوي‌ثريوم يأتي من الملكة أرسينوي التي كان يحمل اسمها منخفض الفيوم الذي عُثر فيه على أحفورات الجنس، في العصر البطلمي، واليونانية: θηρίον (ثريون)، "وحش". كنية النوع النمطي أ. زيتـِلي A. zitteli، أُطلِق تكريماً لعالم الإحاثة الألماني البارز، كارل ألفرد فون تسيتل، الذي يعتبره البعض رائد علم الإحاثة في مصر.[1]

الاكتشاف والأحفورات ذات القربى

ترميم أ. زيتـِلي A. zitteli.

بينما تظل واحة الفيوم الموقع الوحيد الذي عُثر فيه على هياكل كاملة من أحفورات وحوش أرسينوي، فإن بقايا لأقارب أسبق قد عثر عليها في جنوب شرق اوروپا ومنغوليا، في شكل شظايا من فك. تلك الوحوش الأرسينوية المبكرة لم يتم توصيفها رسمياً بعد. أفضل الأنواع المعروفة (وأولها توصيفاً) كانت A. zitteli. النوع الثاني، A. giganteum، أُكتُشف في المرتفعات الإثيوپية في چيلگا في 2003. الأسنان الأحفورية، التي كانت أكبر كثيراً من أسنان A. zitteli، تعود إلى نحو 28-27 مليون سنة مضت[2] المادة المنغولية سُميت Radinskya yupingae، بينما المادة الاوروبية أُعطيت nomen dubium of Crivadiatherium iliescui, وقد سُميت المادة التركية Palaeoamasia kansui (أيضاً nomen dubium).

الوصف

عظام متحجرة لحوض حيوان أرسينوثريوم في المتحف الجيولوجي المصري

وفي حياتهم كانوا يشبهون الخرتيت، وكان البالغون من نوع أ. زيتـِلي ينتصبون بارتفاع 1.75 متر عند الأكتاف ويبلغ طولهم 3 أمتار.[3][4] من أكثر السمات المميزة لأرسينوي‌ثريوم زوج القرون الموجود أعلى الأنف وزوج القرون الشبيهة وزوج القرون الثاني الصغير الشبيه بالمقبض فوق عينيها. كان هيكلها العظمي قوي وأطرافها شبيهة لأطراف الفيلة، وكان وركيها أيضاً شبيهة بأوراك الفيلة.[3] وحوش أرسينوي كانت تتمتع بطاقم أسنان مكون من 44 سنة، وهي الحالة البدائية لأسنان الثدييات المشيمية، بخصائص توحي بأنها كانت راعية انتقائية.

Reconstruction of Arsinoitherium by Mauricio Antón

Arsinoitherium was a heavily built animal, with robust limbs and anatomical adaptations similar to elephants to support their body weight, a condition known as graviportality. The most noticeable feature of the skull of Arsinoitherium are two large horns atop its skull, structurally similar to those of bovids (cattle, goats, and their relatives).[5][6] A second pair of smaller knob-like protuberances sat behind these horns.

الجمجمة

View of the skull from the front, showing the narial openings and prenasal bar

A proboscis or tapir-like lip has been suggested for Arsinoitherium due to the more posterior (rearward) position (retraction) of the narial openings and the morphology of the incisive foramen.[7] The lambdoidal crest is prominent, and the basiocciput forms a straight ventral border against the foramen magnum. The parietal bone is fused to the supraoccipital and is bounded by the lambdoidal crest.[5] The squamosal bone is enlarged and forms most of the lateral wall of the cranium. In the orbit, on the lacrimal bone, there is a small protuberance which connects with the maxilla. The premaxilla of Arsinoitherium is comparatively small, while the maxilla is enlarged and possesses a large jugal process which links to the lacrimal.[5]

The horns of Arsinoitherium were likely extended in life by keratin.

The characteristic horns of Arsinoitherium are derived from the fronto-nasal region of the skull, the frontal bone bearing the entirety of the small horns and a portion of the base of the larger horns, while the nasal possesses the majority of the larger horn's base.[7][5] A form of sexual dimorphism has been suggested, with some specimens having smaller, more erect horns and other having larger, nearly triangular shaped horns.[5] The narial aperture is bifurcated by a prominent vertical prenasal bar.[5] The bar is not present in subadults and is thought to be developed at a later point in life, and is speculated to be an ossification of a cartilaginous nasal septum.[5] The skull is generally narrow and elongated, and the occipital plane is anteriorly slanted. The occipital condyle projects posteriorly and the zygomatic arches are steeply angled on the posterior dorsal side. On the inside, the horns of Arsinoitherium are hollowed out and connect to the frontal sinus system, while on the outside they are covered in vascular striations, which suggest a keratinous growth sheathed the horns in life.

Endocast of A. zitteli

The dentary is elongated and shallow, yet still massively built, with the ramus and coronoid process being elevated. The masseteric fossae are expansive. Below the third premolar, there is a single mandibular foramen.[7][8]

Endocast

Endocasts of Arsinoitherium's brain have been made. In most regards it is similar to that of other large mammals. The olfactory bulbs are smaller than those of the Dinocerata and Pantodonta, though the cerebra are larger comparatively.[5]

التسنين

Teeth of A. giganteum

The teeth of Arsinoitherium are unique in morphology. The teeth are incredibly high crowned or hypsodont, with the molars composed of 2 high transverse columns, and said molars are repeatedly folded, being bilophodont, similar to the teeth of tapirs and elephants.[5][9] The canines and incisors are similar in shape and most likely not used for any combat purposes.[7] The crowns of both are also high, and the outer face of the crown is highly convex. The premolars are strikingly different from the molars, as they exhibit little to no folding.[5] The dental formula of Arsinoitherium is 3.1.4.33.1.4.3,[7][5] though some older sources claim 1.0.4.31.0.4.3.[8] The teeth of A. giganteum are larger than those of A. zitteli, but are morphologically similar.[10][7]

Cervical vertebrae of A.zitteli

العمود الفقري

The vertebrae of Arsinoitherium are incredibly robustly built, with a wide neural arch. The atlas of Arsinoitherium is wider than those found in the Dinocerata, bearing a longer transverse process and a less convex neural arch. The axis has a rounded odontoid process, and the odontoid has deep grooves on each side which separate it from the main articulation points of the axis. The cervical vertebrae have a shortened centrum in relation to the height and width, with the morphology compared to those of elephants. Because of this, the width of movement of the neck has been assumed to be restricted to lateral movements.[5][7] The neural spines of the thoracic vertebrae are angled backwards.

الهيكل العظمي الطرفي

Scapula of A. zitteli
Scapula of A. zitteli
Humerus of A. zitteli
Humerus of A. zitteli
Humerus of A. zitteli
Forelimb bones of A. zitteli

القفص الصدري والأطراف الأمامية

The upper portion of the border between the scapula and the coracoid is slightly convex, and likewise the suprascapular border is separated by a shallow concavity originating from the scapular spine. The spine itself, which is thick and rugose, rises gradually in height from the superior border, ending 3 cm (1.2 in) above the glenoid cavity.[5] The inner face of the scapula is concave, and the scapula generally differs from those of other large bodied mammals in terms of structure.[5]

Similarly to other megafaunal mammals, Arsinoitherium has a graviportal limb structure. The limbs are pillar-like, with the humerus, the radius and the ulna all being robust.[7] The shaft and distal end of the humerus is compressed, and the head is enlarged. There is a large ridge formed from the greater tuberosity, but it is not as developed as in Uintatherium or Elephas.[5] The bones of the forelimb are not coossified, and the ulna is far more robust than the radius. They are morphologically similar to those of Elephas. The radius is short, with the outside of the posterior face possessing an elongated facet which articulates with the ulna, with the texture indicating the two bones were tightly linked. The olecranon process of the ulna is incredibly large, and the bone is generally much thicker than the radius. The shaft of the bone is triangular in shape when viewed in section.[5] The feet are pentadactyl and plantigrade, with the astragalar morphology of Arsinoitherium resembling that of elephants. There are differences, however, and a reconstruction of the forefeet suggests that Arsinoitherium held its forefeet in a more laterally oriented and plantigrade position than extant elephants.[7][11]

Pelvic girdle and hindlimbs

The ilia of the pelvis are flared, with the inner surface being slightly concave. The shape of the acetabulum is oval, and the pit for the round ligament is remarkably deep. On the pubis, the anterior border is also concave.[5] The hindlimbs are similar to the forelimbs. The femur is compressed much like the humerus, as is the tibia. The fibula is elongated and slender, with flared articular ends.[5]

الحجم

Adult Arsinoitherium zitteli stood around 1.75 m (5.7 ft) tall at the shoulders and 3 m (9.8 ft) in length.[5][12] A. giganteum was larger than A. zitteli, with proportionally longer limbs.[7] Mass estimates for A. zitteli range from 510–1،500 kg (1،120–3،310 lb) while A. giganteum is estimated have been be around 1،760–1،960 kg (3،880–4،320 lb).[7]

علم الأحياء العتيق

المأكل

Arsinoitherium and apterodontine hyaenodonts are known to have coexisted (art by Charles R. Knight, note that the hyaenodont depicted is Pterodon, which did not coexist with Arsinoitherium)

Arsinoitherium was likely a browser, indicated by the morphology of the incisor teeth.[9] The environments Arsinoitherium inhabited were wet, humid forests, being fluvial and shallow marine deposits.[13] These localities have an array of both terrestrial as well as aquatic and even marine fauna, and some authors have posited that Arsinoitherium may have had semi-aquatic habits due to the morphology of the forelimbs.[14] This has been disputed, however, as analysis of stable isotopes reveals the genus was most likely primarily terrestrial.[15]

الاتصال

Arsinoitherium, like modern elephants, had the ability to communicate via foot drumming and loud, low frequency vocalisations. Its cochlear canal lacked a secondary bony lamina, an indicator of an adaptation for hearing low frequency sounds.[16]

البيئة العتيقة

In Dor-El-Talha, a fossil locality in Libya, the genus is known to have lived alongside many species, including members of the suborder Hyracoidea, apterodontine hyaenodonts,[17][18] the proboscideans Palaeomastodon, Barytherium and Moeritherium as well as the giant snake Gigantophis.[13] Fish are also known, with silurid catfish, gar, sawfish and lungfish being common.[13] Crocodilians are also known from the locality.[19]

Fossils of Arsinoitherium have been found in:[20]

Eocene
Oligocene


الهامش

  1. ^ Beadnell, H.G.C. (1902). "A preliminary note on Arsinoitherium zitteli, Beadnell, from the Upper Eocene strata of Egypt". Public Works Ministry, National Printing Department. Cairo: 1–4.
  2. ^ Sanders, W.J., Kappelman, J., and Rasmussen, D.T. 2004. New large−bodied mammals from the late Oligocene site of چيلگا، إثيوپيا. Acta Palaeontologica Polonica 49 (3): 365–392.[1]
  3. ^ أ ب Andrews, C.W. A descriptive catalogue of the Tertiary Vertebrata of the Fayûm. British Museum, London. Taylor and Francis. p. 324.
  4. ^ Mondéjar-Fernández; et al. (2008). "El género Arsinoitherium: catálogo de la colección inédita del Muséum d'Histoire Naturelle de París y el problema del número de especies". Palaeontologica Nova (in Spanish). SEPAZ (8): 292–304. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: unrecognized language (link)
  5. ^ أ ب ت ث ج ح خ د ذ ر ز س ش ص ض ط ظ ع غ Andrews, C.W. (1906). A descriptive catalogue of the Tertiary Vertebrata of the Fayûm. British Museum, London. Taylor and Francis. p. 324.
  6. ^ Anonymous. (1903). A New Egyptian Mammal (Arsinoitherium) from the Fayûm. (1903). Geological Magazine, 10(12), 529-532.
  7. ^ أ ب ت ث ج ح خ د ذ ر ز خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة Werdelin-2010
  8. ^ أ ب خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة Beadnell-1902
  9. ^ أ ب Court, Nicholas (1992-02-01). "A unique form of dental bilophodonty and a functional interpretation of peculiarities in the masticatory system of Arsinoitherium (mammalia, Embrithopoda)". Historical Biology. 6 (2): 91–111. Bibcode:1992HBio....6...91C. doi:10.1080/10292389209380421. ISSN 0891-2963.
  10. ^ خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة Sanders-2004
  11. ^ Court, Nicholas (1993-01-01). "Morphology and functional anatomy of the postcranial skeleton in Arsinoitherium (Mammalia, Embrithopoda)". Palaeontographica Abteilung A (in الإنجليزية): 125–169.
  12. ^ Mondéjar-Fernández; et al. (2008). "El género Arsinoitherium: catálogo de la colección inédita del Muséum d'Histoire Naturelle de París y el problema del número de especies". Palaeontologica Nova (in Spanish). SEPAZ (8): 292–304.{{cite journal}}: CS1 maint: unrecognized language (link)
  13. ^ أ ب ت Fleagle, John G.; Gilbert, Christopher C. (2007-12-03). Elwyn Simons: A Search for Origins (in الإنجليزية). Springer Science & Business Media. ISBN 978-0-387-73896-3.
  14. ^ Al-Sayigh, Abdul Razak; Nasir, Sobhi; Schulp, Anne S.; Stevens, Nancy J. (2008-03-01). "The first described Arsinoitherium from the upper Eocene Aydim Formation of Oman: Biogeographic implications". Palaeoworld (in الإنجليزية). 17 (1): 41–46. doi:10.1016/j.palwor.2007.07.005. ISSN 1871-174X.
  15. ^ Clementz, Mark T.; Holroyd, Patricia A.; Koch, Paul L. (1 September 2008). "Identifying Aquatic Habits of Herbivorous Mammals Through Stable Isotope Analysis". PALAIOS. 23 (9): 574–585. doi:10.2110/palo.2007.p07-054r.
  16. ^ Benoit, Julien; Merigeaud, Samuel; Tabuce, Rodolphe (September–October 2013). "Homoplasy in the ear region of Tethytheria and the systematic position of Embrithopoda (Mammalia, Afrotheria)". Geobios (in الإنجليزية). 46 (5): 357–370. doi:10.1016/j.geobios.2013.07.002. Retrieved 11 May 2026 – via Elsevier Science Direct.
  17. ^ Grohé, Camille; Morlo, Michael; Salem, Mustapha; Jaeger, Jean-Jacques (2010-10-01). "The oldest Apterodontinae (Hyaenodontidae, "Creodonta") from the middle Eocene of Dor el Talha (Libya)". Society of Vertebrate Paleontology.
  18. ^ Grohé, Camille; Morlo, Michael; Chaimanee, Yaowalak; Blondel, Cécile; Coster, Pauline; Valentin, Xavier; Salem, Mustapha; Bilal, Awad A.; Jaeger, Jean-Jacques; Brunet, Michel (2012). "New Apterodontinae (Hyaenodontida) from the Eocene locality of Dur At-Talah (Libya): systematic, paleoecological and phylogenetical implications". PLOS ONE. 7 (11) e49054. doi:10.1371/journal.pone.0049054. ISSN 1932-6203. PMC 3504055. PMID 23185292.
  19. ^ Agrasar, Eduardo Llinás (2004-10-01). "Crocodilian remains from the Upper Eocene of Dor-El-Talha, Libya". Annales de Paléontologie. 90 (4): 209–222. doi:10.1016/j.annpal.2004.05.001. ISSN 0753-3969.
  20. ^ Arsinoitherium at Fossilworks.org

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