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The Cuban Crocodile (Crocodylus rhombifer) from Late Quaternary Underwater Cave Deposits in the Dominican Republic
American Museum Novitates ( IF 1.5 ) Pub Date : 2018-12-21 , DOI: 10.1206/3916.1
Gary S. Morgan 1 , Nancy A. Albury 2 , Renato Rímoli 3 , Phillip Lehman 4 , Alfred L. Rosenberger 5 , Siobhán B. Cooke 6
Affiliation  

ABSTRACT Late Quaternary fossils representing a locally extinct population of the Cuban crocodile (Crocodylus rhombifer) are reported from two underwater caves in the Dominican Republic. A large fossil sample of C. rhombifer, from Oleg's Bat Cave near Bavaro in the southeastern Dominican Republic, consists of four nearly complete skulls, numerous isolated cranial elements and mandibles, and more than 100 postcranial bones representing most of the skeleton. These fossils were collected from a completely submerged portion of the cave at a depth of 11 m and about 100 m from the nearest entrance. A skull, mandibles, and two vertebrae of a Cuban crocodile were also found in a second cave called Ni-Rahu, northeast of Santo Domingo. We identify the fossil crocodile skulls from the Dominican Republic as Crocodylus rhombifer because they share the following characters with modern skulls of C. rhombifer from Cuba (as well as fossil skulls from Cuba, the Bahamas, and Cayman Islands): short, broad, and deep rostrum; large orbits; convex nasals along the midline (midrostral boss); prominent swelling on the lacrimals anterior and medial to the orbits; low but obvious ridges extending anteriorly from the lacrimals to the nasals and posteriorly from the lacrimals to the prefrontals and frontals, outlining a distinct diamond- or rhomboid-shaped structure; strongly concave interorbital region and cranial roof; high, narrow ridges on the internal margins of the orbits, extending from the prefrontals to the frontals and posteriorly to the postorbitals; prominent ridges along the lateral margins of the cranial roof on the postorbitals and squamosals, terminating as noticeable protuberances on the posterolateral corners of the squamosals; premaxillary/maxillary suture on the palate essentially horizontal or transverse to the long axis of the skull at the level of the first maxillary tooth; 13 teeth in the maxilla. Certain aspects of the ecology and anatomy of living Crocodylus rhombifer in Cuba, and carbon isotope data from fossil crocodile bones from both the Dominican Republic and the Bahamas, indicate that the Cuban crocodile is a terrestrially adapted predator. The fossil deposits in Oleg's Bat Cave and other underwater caves in the Dominican Republic lack freshwater vertebrates, such as fish and turtles, but contain abundant samples of hystricognath rodents, small ground sloths, and other terrestrial vertebrates, including large land tortoises, that apparently were the primary prey of the crocodiles. Bats are abundant in the fossil deposits in Oleg's Bat Cave, and may have been an additional food source. Bone collagen from a tibia of C. rhombifer from Oleg's Bat Cave yielded an AMS radiocarbon date of 6460 ±30 ryrBP (equivalent to 7320 to 7430 cal yrBP). The chronology for the local extinction of C. rhombifer in Hispaniola is currently unknown, except to document the presence of this species in the eastern Dominican Republic in the early Holocene. Radiocarbon dates and historical records confirm that Cuban crocodiles survived into the period of European colonization (post-1492) in the Bahamas and on Grand Cayman. The only species of crocodile currently found in Hispaniola, the American crocodile (C. acutus), occurs in coastal marine habitats and in two inland brackishwater lakes: Lago Enriquillo in the Dominican Republic and the nearby Etang Saumâtre in Haiti. C. acutus has no fossil record in Hispaniola or elsewhere in the West Indies, suggesting that this species may be a very recent (late Holocene) immigrant in the Antillean region. Crocodylus rhombifer has one of the most limited geographic ranges of any living crocodylian species, known only from freshwater swamps in south-central Cuba and the Isla de Juventud (Isla de Pinos) off the southwestern coast of Cuba. Locally extinct or extirpated populations of C. rhombifer from fossil deposits in the Dominican Republic, Grand Cayman, and the Bahamas document a considerably wider distribution for this species during the Late Quaternary.

中文翻译:

来自多米尼加共和国晚第四纪水下洞穴沉积物的古巴鳄鱼(Crocodylus rhombifer)

摘要 多米尼加共和国的两个水下洞穴报告了代表古巴鳄鱼(Crocodylus rhombifer)当地灭绝种群的晚第四纪化石。来自多米尼加共和国东南部巴瓦罗附近的 Oleg's Bat Cave 的大型 C. rhombifer 化石样本包括四个几乎完整的头骨、许多孤立的颅骨元素和下颌骨,以及 100 多块代表大部分骨骼的颅后骨骼。这些化石是从洞穴完全淹没的部分收集的,深度为 11 m,距离最近的入口约 100 m。在圣多明各东北部的第二个名为 Ni-Rahu 的洞穴中还发现了古巴鳄鱼的头骨、下颌骨和两块椎骨。我们将来自多米尼加共和国的鳄鱼头骨化石确定为 Crocodylus rhombifer,因为它们与来自古巴的现代鳄鱼头骨(以及来自古巴、巴哈马和开曼群岛的化石头骨)具有以下特征:短、宽和深邃的讲台;大轨道;沿中线凸出的鼻梁(midrostral boss);眼眶前部和内侧的泪腺明显肿胀;低但明显的脊从泪腺向前延伸到鼻骨,从泪腺向后延伸到前额骨和额骨,勾勒出独特的菱形或菱形结构;强烈凹陷的眶间区和颅顶;眼眶内缘有高而窄的脊,从前额叶延伸到额叶,再向后延伸到眶后;在眶后和鳞状骨上沿着颅顶的侧缘有突出的脊,在鳞状骨的后外侧角处终止为明显的突起;上颌前颌骨/上颌骨缝合线在第一颗上颌牙水平与颅骨长轴基本水平或横向;上颌有13颗牙齿。古巴活鳄鱼的生态学和解剖学的某些方面,以及来自多米尼加共和国和巴哈马的鳄鱼化石化石的碳同位素数据,表明古巴鳄鱼是一种适应陆地的捕食者。奥列格蝙蝠洞和多米尼加共和国其他水下洞穴中的化石沉积物缺乏淡水脊椎动物,如鱼和海龟,但含有丰富的 hystricognath 啮齿动物、小型地面树懒、和其他陆生脊椎动物,包括大型陆龟,显然是鳄鱼的主要猎物。蝙蝠在奥列格蝙蝠洞的化石沉积物中很丰富,可能是额外的食物来源。来自 Oleg's Bat Cave 的 C. rhombifer 胫骨的骨胶原产生了 6460 ±30 ryrBP(相当于 7320 到 7430 cal yrBP)的 AMS 放射性碳数据。除了记录该物种在全新世早期在多米尼加共和国东部的存在外,目前尚不清楚伊斯帕尼奥拉岛 C. rhombifer 局部灭绝的年表。放射性碳测年和历史记录证实,古巴鳄鱼在巴哈马和大开曼群岛存活到欧洲殖民时期(1492 年后)。目前在伊斯帕尼奥拉岛发现的唯一鳄鱼种类,美洲鳄鱼(C. acutus),发生在沿海海洋栖息地和两个内陆半咸水湖泊:多米尼加共和国的恩里基洛湖和海地附近的 Etang Saumâtre。C. acutus 在伊斯帕尼奥拉岛或西印度群岛的其他地方没有化石记录,这表明该物种可能是安的列斯地区最近的(全新世晚期)移民。Crocodylus rhombifer 是现存鳄鱼物种中地理范围最有限的物种之一,仅在古巴中南部的淡水沼泽和古巴西南海岸附近的青年岛(Isla de Pinos)中发现。从多米尼加共和国、大开曼岛和巴哈马群岛的化石沉积物中当地灭绝或灭绝的 C. rhombifer 种群记录了该物种在第四纪晚期的广泛分布。多米尼加共和国的 Lago Enriquillo 和海地附近的 Etang Saumâtre。C. acutus 在伊斯帕尼奥拉岛或西印度群岛的其他地方没有化石记录,这表明该物种可能是安的列斯地区最近的(全新世晚期)移民。Crocodylus rhombifer 是现存鳄鱼物种中地理范围最有限的物种之一,仅在古巴中南部的淡水沼泽和古巴西南海岸附近的青年岛(Isla de Pinos)中发现。从多米尼加共和国、大开曼岛和巴哈马群岛的化石沉积物中当地灭绝或灭绝的 C. rhombifer 种群记录了该物种在第四纪晚期的广泛分布。多米尼加共和国的 Lago Enriquillo 和海地附近的 Etang Saumâtre。C. acutus 在伊斯帕尼奥拉岛或西印度群岛的其他地方没有化石记录,这表明该物种可能是安的列斯地区最近的(全新世晚期)移民。Crocodylus rhombifer 是现存鳄鱼物种中地理范围最有限的物种之一,仅在古巴中南部的淡水沼泽和古巴西南海岸附近的青年岛(Isla de Pinos)中发现。从多米尼加共和国、大开曼岛和巴哈马群岛的化石沉积物中当地灭绝或灭绝的 C. rhombifer 种群记录了该物种在第四纪晚期的广泛分布。acutus 在伊斯帕尼奥拉岛或西印度群岛的其他地方没有化石记录,这表明该物种可能是安的列斯地区最近的(全新世晚期)移民。Crocodylus rhombifer 是现存鳄鱼物种中地理范围最有限的物种之一,仅在古巴中南部的淡水沼泽和古巴西南海岸附近的青年岛(Isla de Pinos)中发现。从多米尼加共和国、大开曼岛和巴哈马群岛的化石沉积物中当地灭绝或灭绝的 C. rhombifer 种群记录了该物种在第四纪晚期的广泛分布。acutus 在伊斯帕尼奥拉岛或西印度群岛的其他地方没有化石记录,这表明该物种可能是安的列斯地区最近的(全新世晚期)移民。Crocodylus rhombifer 是现存鳄鱼物种中地理范围最有限的物种之一,仅在古巴中南部的淡水沼泽和古巴西南海岸附近的青年岛(Isla de Pinos)中发现。从多米尼加共和国、大开曼岛和巴哈马群岛的化石沉积物中当地灭绝或灭绝的 C. rhombifer 种群记录了该物种在第四纪晚期的广泛分布。仅在古巴中南部的淡水沼泽和古巴西南海岸附近的青年岛(Isla de Pinos)中发现。从多米尼加共和国、大开曼岛和巴哈马群岛的化石沉积物中当地灭绝或灭绝的 C. rhombifer 种群记录了该物种在第四纪晚期的广泛分布。仅在古巴中南部的淡水沼泽和古巴西南海岸附近的青年岛(Isla de Pinos)中发现。从多米尼加共和国、大开曼岛和巴哈马群岛的化石沉积物中当地灭绝或灭绝的 C. rhombifer 种群记录了该物种在第四纪晚期的广泛分布。
更新日期:2018-12-21
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