【历史】鱼龙形下纲/Ichthyosauromorpha的科学研究编年史（1990~1999)

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除此之外这科普专栏帖“有可能”是本人在哔哩哔哩最后一次制作的古生物学相关科普内容，因此本人从明年起不再推出古生物学科普内容。敬请原谅！！！！！~~~~~

鱼龙形下纲/Ichthyosauromorpha的科学研究编年史是古生物学史上按时间顺序排列的事件的列表，鱼龙形下纲/Ichthyosauromorpha是一种海生的蜥形纲物种类群，不少物种的外形类似于鲸下目/Cetacea、鲨形超目/Selachimorpha和旗鱼目/Istiophoriformes。科学家至少在17世纪末就记载过鱼龙形下纲/Ichthyosauromorpha的物种化石，当时一位名叫爱德华·拉维德/Edward Lhwyd的学者出版了一本有关英格兰化石的书，该书将一些鱼龙形下纲物种的椎骨错误鉴定为鱼类化石；直到19世纪人们才开始了解到鱼龙形下纲/Ichthyosauromorpha物种的真面目。在1811年一个名叫约瑟夫·安宁·杰弗里/Joseph Anning Jeffrey的男孩发现了人类已知最早的鱼龙形下纲/Ichthyosauromorpha化石记载，这些化石在科学上也得到了公认，后来他的妹妹玛丽·安宁/Mary Anning找到了骨骼的其余部分，并继续成为受人尊敬的化石收藏家和古生物学家。

科学家对鱼龙形下纲/Ichthyosauromorpha的早期研究认为该物种类群是海洋蜥形纲物种，但对其解剖结构和生态行为等主要知识未完全了解，人们经常将它们描绘成经常在海滩上晒日光浴的水陆两栖动物，并且尾巴笔直。尽管人类已知最早找到的鱼龙形下纲/Ichthyosauromorpha化石标本中可以看到鱼龙属/Ichthyosaurus的尾椎的末端向下弯曲，但学者们早期认为鱼龙属/Ichthyosaurus的尾椎的末端向下弯曲是因为尸体遭受破坏。事实上这种尾巴向下弯曲是鱼龙形下纲/Ichthyosauromorpha大多数物种常见的生前特征，以至于学者们最后意识到尾椎的末端向下弯曲是那些化石的自然正常的生前特征，尾椎骨上方并支撑着鲨鱼状的尾鳍。科学家们开始意识到鱼龙形下纲/Ichthyosauromorpha极度特化成纯水生/Aquatic物种，甚至会以卵胎生/Ovoviviparity方式生产后代。鱼龙形下纲/Ichthyosauromorpha的产子证据可追溯到1846年，当时查尔斯·皮尔斯/Chaning Pierce向理查德·欧文/Richard Owen爵士报告发现到鱼龙属/Ichthyosaurus的胚胎化石。

鱼龙形下纲/Ichthyosauromorpha的化石发现与其科学研究一直持续到20世纪。1928年西缅·穆勒/Simeon Muller在内华达州发现了40只的巨型物种化石。但是直到1950年代中期，查尔斯·刘易斯·坎普/Charles Lewis Camp 和 加利福尼亚州大学伯克利分校/University of California, Berkeley的 塞缪尔·保罗·威尔斯/Samuel Paul Welles 为此目的进行探险之前，才发掘这些鱼龙形下纲/Ichthyosauromorpha物种的巨型化石遗骸，这些化石的发掘将需要十多年的时间，而查尔斯·刘易斯·坎普/Charles Lewis Camp对这些骨骸化石的研究结果要到1975年去世后一年才公布。这些巨型鱼龙被命名为秀尼龙属·通俗种/Shonisaurus popularis，其后的该地点现在已被命名为贝林鱼龙国家公园/Berlin–Ichthyosaur State Park。

20世纪晚期对鱼龙形下纲/Ichthyosauromorpha的研究有显着的进展，包括新建一种物种属，即真鼻龙属·长嘴种/Eurhinosaurus longirostris，在此之前自1854年以来就被错误地归类为鱼龙属/Ichthyosaurus里。1986年克里斯托弗·麦克高恩/Christopher McGowan用亚瑟王的神话般的剑来命名了另一种在英格兰发现过外形很类似真鼻龙属/Eurhinosaurus的物种，即王者之剑龙属·克斯提种/Excalibosaurus costini。在1990年代末和21世纪初，关于整个鱼龙形下纲/Ichthyosauromorpha该物种类群灭绝的原因，一直引起学术界的争议性，例如有一种假说认为是来自于在森诺曼阶/Cenomanian或其后时代的土仑阶/Turonian新兴演化出的默兹蜥超科（沧龙超科）/Mosasauroidea物种类群竞争。

1990
    Bradley Kosch of Berlin-Ichthyosaur State Park criticized Camp's 1980 reconstruction of the park's famous Shonisaurus popularis as having too short a backbone and overly deep ribs, responsible for its supposedly deep pot belly. He noted that the illustration differed from both the text of Camp's published description and his own private field notes.
    Stephen Jay Gould published an article about the tail bend in ichthyosaurs.
    De Buffrenil and Mazin found a woven texture in the bones of Ichthyosaurus, Omphalosaurus, and Stenopterygius. This texture is found only in the bones of quickly growing animals, suggesting that ichthyosaurs had high metabolic rates and may even have been warm blooded.
    Massare and Callaway observed that Triassic ichthyosaurs had more elongated body plans than their Jurassic successors.

1990年
    柏林鱼龙国家公园的布拉德利·科斯/Bradley Kosch反驳查尔斯·刘易斯·坎普/Charles Lewis Camp在1980年对公园著名的肖尼龙属·通俗种/Shonisaurus popularis的复原图，因为肖尼龙属·通俗种的骨干太短、肋骨过深甚至批评胸腹肚腩被复原成过大。布拉德利·科斯指出，该肖尼龙的复原图不仅和查尔斯·刘易斯·坎普的公开文字描述有出入，也和查尔斯·刘易斯·坎普自己的私人实地记载有出入。
    斯蒂芬·杰伊·古尔德/Stephen Jay Gould发表了一篇关于鱼龙类物种尾巴弯曲的文章。
    德布弗里尼尔/De Buffrenil和马赞/Mazin在鱼龙属/Ichthyosaurus、眼睛龙属/Omphalosaurus和狭鳍龙属/Stenopterygius的骨头中发现了编织纹理，这种在骨头里编织纹理仅在生产速度较快的动物骨骼身上才能发现到，这显示鱼龙类物种的新陈代谢率很高，甚至可能是中温动物或恒温动物。
    马萨雷和卡拉威观察到，三叠纪的鱼龙类物种的胴体比例，比侏罗纪后代的胴体比例更长。

1991
    An archaeologist named Keary Walde discovered large fossil bones near the Sikanni Chief River. He reported his discovery to the Royal Tyrell Museum. The museum's curator, Elizabeth Nicholls, was also a respected marine reptile researcher, visited the site.
Skeletal reconstruction of a Stenopterygius with young partially evacuated from the birth canal. These specimens may not reflect the preservation of mothers in the act of giving birth, but deceased feti being expelled from her by pressure resulting from gas build up in her bloating carcass.
She was astonished to realize that the bones discovered by Walde were the remains of an ichthyosaur roughly 75 feet long, one and a half times as big as the largest known ichthyosaur at the time.
    McGowan argued that ichthyosaur fossils with new-born remains protruding from the birth canal don't imply that the mother died giving birth. Instead, they could be expelled from an already dead mother by the pressure of gas-build up as her rotting carcass bloated. An example of this in modern marine life was documented where the carcasses of beached false killer whales were given a shallow burial. Several months later, the pregnant females' fetuses had been partly expelled. He also observed that roughly 35 ichthyosaur specimens a year were still being recovered from Holzmaden. He suggested that at least some ichthyosaurs may have been warm-blooded and swift swimming like modern tuna due to their similar body plans. He also noted that even if they weren't warm blooded their large body mass would help maintain stable body temperatures.
    Lingham-Soliar referred to the swimming style of advanced ichthyosaurs whose body remained stiff while large muscles powered the tail's swimming stroke as "axial oscillation".
    Mazin and others described the new genus and species Thaisaurus chonglakmanii.

1991年
    一位名叫基里·瓦尔德/Keary Walde的考古学家在西肯尼酋长河附近发现了大块化石，并把发现报告献给皇家泰瑞尔博物馆/Royal Tyrell Museum。皇家泰瑞尔博物馆的策展人伊丽莎白·尼科尔斯/Elizabeth Nicholls也是一位受人尊敬的海生蜥脸纲研究者，他参观了该遗址。令伊丽莎白·尼科尔斯惊讶的是，基里·瓦尔德发现的骨头是身长大约22.86米（75英尺）长的鱼龙类物种的骨骸化石。
    克里斯托弗·麦克高恩/Christopher McGowan研究认为，怀孕的鱼龙类化石以及从产道挤出的新生尸骸并不意味着母亲死于分娩难产。相反地由于尸体在腐烂过程种累积的气体压力快速膨胀可能将它们从已经死去的母亲尸体中排挤出去。类似的情况在现代海洋动物物种也有类似的案例：已怀孕搁浅而死的伪虎鲸/Pseudorca crassidens母亲尸体被进行了浅埋葬，几个月后孕妇的死胎全身被部分挤出母亲死尸体外。克里斯托弗·麦克高恩在此之前观察过霍尔茨马登/Holzmaden市镇当地人士每年采集到约35具体鱼龙类化石物种标本。克里斯托弗·麦克高恩提出由于鱼龙类物种与鲭科(金枪鱼科)/Scombridae相似的身体结构，因此推测有些鱼龙类物种可能像现代鲭科一样是中温动物并能快速游泳。克里斯托弗·麦克高恩还指出即使鱼龙类物种不是恒温动物，他们的大体型的面积也会有助于维持自身体温稳定。
    林汉姆·索里亚尔/Lingham-Soliar将鱼龙类的高级演化物种的身体保持僵硬，而大块肌肉为尾巴的游泳冲程提供动力，因此称为“轴向振荡/axial oscillation”。
    马津/Mazin和其他学者新描述一个鱼龙类物种，泰国龙属·崇勒玛尼种/Thaisaurus chonglakmanii。

1992
    Field work on behalf of Alberta's Royal Tyrell Museum began in the Pink Mountains of British Columbia 60 miles north of where Christopher McGowan's field work was conducted. The Royal Tyrell researchers would discover Late Triassic ichthyosaur remains in the sediments of the Pardonet Formation.
    Judy Massare proposed an explanation for the high percentage of pregnant Stenopterygius at Holzmaden. She speculated that the area was used as a breeding ground, the way whales congregate to give birth in areas of shallow water today. The coordination of a large number of births at the same time and place would increase the young's chances of survival because there would be too many for the local predator population to eat. Massare suggested that another ichthyosaur genus, Leptopterygius (now known as Leptonectes), was one such local predator that may have fed on vulnerable young ichthyosaurs.
    Nathalie Bardet dismissed claims of ichthyosaur fossils from rocks of more recent age than the Cenomanian. She also discussed possible causes for the extinction of the ichthyosaurs. She expressed doubt that ichthyosaurs were replaced by mosasaurs because they would not be in direct competition with each other. Instead she posited a connection to an extinction event that affected cephalopods at the boundary between the Cenomanian and Turonian ages. She proposed that the disappearance of these many cephalopod species may have deprived ichthyosaurs of their food source and caused their extinction.

1992年
    这一年克里斯托弗·麦克高恩/Christopher McGowan的团队为加拿大阿尔伯塔省的皇家泰瑞尔博物馆/Royal Tyrell Museum，开始对不列颠哥伦比亚省的粉红色山脉地区的北面60英里进行野外考察。皇家泰瑞尔大学的研究人员将在帕多内特组/Pardonet Formation的沉积物中发现三叠纪晚期的鱼龙类物种骨骸化石。
    朱迪·马萨雷/Judy Massare对霍尔茨马登/Holzmaden市镇当地的狭鳍龙属/Stenopterygius怀孕母亲化石占了当地百分比化石数量提出了一种解释。她推测该地区曾被用作狭鳍龙的繁殖场，类似于鲸下目/Cetacea现代物种在海湾浅水区聚集分娩产子的习性。狭鳍龙在同一时间和地点同时进行大量分娩产子的会增加年轻个体的生存率，因为当地天敌掠食者的数量太多了。马萨雷/Massare推测另一种鱼龙类物种属即纤细泳龙属/Leptonectes，可能是以比较脆弱的鱼龙类物种幼年个体为食的当地掠食动物。
    纳塔莉·巴戴/Nathalie Bardet反对鱼龙类化石截止至森诺曼阶/Cenomanian再也无往后化石记载的假说，纳塔莉·巴戴还提出鱼龙类物种灭绝的可能原因。她对鱼龙类物种被莫兹蜥超科（被沧龙超科）/Mosasauroidea取代表示质疑，因为它们之间没有任何直接竞争关系的证据。反而是纳塔莉·巴戴认为鱼龙类物种消失与灭绝事件有联系，她提出森诺曼阶-土伦阶边界事件/Cenomanian-Turonian boundary event导致鱼龙类物种的主要食物来源头足纲/Cephalopoda软体动物的锐减甚至物种灭绝，而导致了鱼龙类物种全族灭绝。

1993
    Charles Deeming and others published a paper on the 1985 ichthyosaur embryo discovered in Somerset. They observed that many pregnant ichthyosaur specimens contain fetuses oriented head-first toward the birth canal even though they were probably born tail-first as a precaution to prevent drowning. This suggests that there may have been complications during the pregnancy, like the fetus being too large to pass through the birth canal. If the decomposing fetus remained trapped in the mother, it would very likely kill her.
    Jennifer Hogler re-examined the tails of the early large ichthyosaurs Cymbospondylus and Shonisaurus, finding the wedge-shaped vertebrae that form the tail-bend that composes the tail fluke. This find contradicted the widespread idea that these early ichthyosaurs had straight tails and therefore lacked well-developed flukes.
    Russell described the species that would later come to be known as Arthropterygius chrisorum.
    McGowan described the species that would later come to be known as Leptonectes solei.

1993年
    查尔斯·迪明/Charles Deeming等学者发表了一篇关于在1985年萨默塞特/Somerset发现的鱼龙类幼儿化石的论文，他们观察到许多怀孕的鱼龙类化石标本包含头颅露出产道的幼儿，尽管鱼龙类物种幼儿可能具有被出生于尾巴下方作为预防溺水的预防措施，这表明某些母子在怀孕期间可能有并发症，例如幼儿体型太大而无法排出产道。如果死胎卡住母亲产道并开始腐烂，很可能会害死该母亲。
    珍妮弗·霍格勒/Jennifer Hogler重新检查三叠纪的鱼龙类大型物种中的船椎龙属/Cymbospondylus和秀尼龙属/Shonisaurus的尾巴结构，发现形成尾弯的楔形椎骨构成了尾鳍。这一发现与普遍对鱼龙尾鳍的观点相矛盾，即早期的鱼龙尾巴呈笔直外形，因此缺乏发达的尾巴结构。
    罗素/Russel新建和命名鱼龙类物种"Ophthalmosaurus" chrisorum，后来被重新命名学名和分类为肘鳍龙/Arthropterygius chrisorum的物种。
    克里斯托弗·麦克高恩/Christopher McGowan新建和命名鱼龙类物种"Leptopterygius" solei，后来被重新命名学名和分类为纤细泳龙/Leptonectes solei。

1994
    Axel Hungerbuhler bemoaned the taxonomic confusion caused by German geologist Friedrich Quenstedt's early research on the ichthyosaurs at Holzmaden. He attributed the bulk of this confusion to Quenstedt's unorthodox naming practices, which often exceeded the two-named binomials of standard biological nomenclature to consist of three or four names. Further, the fossils themselves were poorly organized and many of the type specimens he founded species on were unlabeled. Hungerbuhler named two new species of his own: Stenopterygius cuniceps and S. macrophasma.
    Christopher McGowan named the new species of Shastasaurus discovered in British Columbia S. neoscapularis. He also reviewed the species previously referred to the genus, finding many of them to be dubious, like S. altus, S. careyi, S. carinthiacus, and S. osmonti. However, two previously described species, the type, S. pacificus, and the referred species S. alexandrae were found to be valid. He criticized Merriam for oversplitting Shastasaurus because most of the resulting names were useless and mislead the paleontological community into thinking that the genus was better understood than it really was.
    Fernandez described the new ichthyosaur genus Chacaisaurus from the Vaca Muerta Formation of Argentina.
    Bardet and others reported Platypterygius fossils from late Cenomanian rocks in Bavaria. These were the remains latest known ichthyosaurs.
    Fernández described the species that would later come to be known as Stenopterygius cayi.

1994年
    阿克塞尔·亨格勒/Axel Hungerbuhler批评德国地质学家弗里德里希·昆斯泰特/Friedrich Quenstedt对霍尔茨马登/Holzmaden市镇当地的鱼龙的早期研究引起的分类混乱。他将这种混乱的大部分归因于昆斯泰特/Quenstedt的非正统命名惯例，该惯例通常超过了标准生物学命名法的双名法和标准生物学术语法（由三个或四个名称组成）。此外当地化石组织本身组织不善，该组织建立的许多化石类型标本都没有标签具体学名。亨格布勒/Hungerbuhler自己命名了狭鳍龙属/Stenopterygius两种笔下新物种：Stenopterygius cuniceps和Stenopterygius macrophasma。
    克里斯托弗·麦克高恩/Christopher McGowan命名了来自于不列颠哥伦比亚省的萨斯特龙属/Shastasaurus新笔下物种，Shastasaurus neoscapularis（该物种后来被重新命名学名和重新分类成独立物种，卡洛维龙/Callawayia neoscapularis ）。克里斯托弗·麦克高恩重新鉴定被分类到萨斯特龙属的物种，发现其中物种许多具有可疑性，例如Shastasaurus altus、Shastasaurus careyi, Shastasaurus carinthiacus和Shastasaurus osmonti，但发现两个先前描述的物种，即S. pacificus类型和所指物种S. alexandrae是有效的。克里斯托弗·麦克高恩批评约翰·坎贝尔·梅里亚姆/John Campbell Merriam过度为萨斯特龙属新建立属下物种，因为萨斯特龙属大多数所谓笔下物种是无效学名物种，并且误导了古生物学界。
    费尔南德斯新建立和命名来自阿根廷的瓦卡穆尔塔组/Vaca Muerta Formation的鱼龙类物种，"Chacaisaurus"。
    巴德/Bardet和其他学者报道发现了巴伐利亚晚期切诺曼尼亚岩中的扁鳍龙属/Platypterygius化石，该化石是已知出现地层最晚的鱼龙类化石，而扁鳍龙属是目前已知生存最晚的鱼龙类物种。

1995年
    January: A man named Chris Moore discovered much of the front half of an ichthyosaur skeleton in the Belemnite Marls of Seatown, Dorset. The specimen was a juvenile of a new Leptopterygius species, named L. moorei after Moore. In life, the specimen was probably about 8 feet long.
    McGowan renamed the ichthyosaur genus Leptopterygius to Leptonectes. He also synonymized Leptopterygius with Temnodontosaurus. He also described the new genus and species Hudsonelpidia brevirostris.
    Martill claimed that despite an abundance of ichthyosaur specimens with preserved soft tissue, there was no evidence that ichthyosaur skin was covered in scales.
    Tichy described the new species Omphalosaurus wolfi .
    Nicholls and Brinkman described the new genus and species Parvinatator wapitiensis.

1995年
     一月：一个名叫克里斯·摩尔/Chris Moore的人在多塞特郡西镇的贝伦尼特泥沼中发现了鱼龙骨架前半部分的大部分。 该标本是一种新的“Leptopterygius”物种的幼体，以摩尔的名字命名为“Leptopterygius moorei”。 估计这个标本生前全身大概有 8 英尺长。
     克里斯托弗·麦克高恩/Christopher McGowan将“Leptopterygius”重新命名为纤细泳龙属/Leptonectes。他还将“Leptopterygius”与切割齿龙属/Temnodontosaurus视为同物异名。 他还描述了新的属和种为 哈德森希望龙/Hudsonelpidia brevirostris。
     马蒂尔/Martill声称，尽管有大量具有保存软组织的鱼龙标本，但没有证据表明鱼龙类物种皮肤有被鳞片覆盖。
     蒂奇/Tichy描述了新物种 纽扣龙/Omphalosaurus wolfi。
     尼科尔斯/Nicholls和布林克曼/Brinkman描述了新属和种 Parvinatator wapitiensis。

1996年
    Motani and others argued that sharks are the best modern analogues for ichthyosaurs because of their similar body plans.
    McGowan reported the serendipitous discovery of evidence for a new giant ichthyosaur species in a museum collection. He was studying the ichthyosaur fossils curated by the National Academy of Sciences in Philadelphia. One Early Jurassic bone catalogued as a part of a shoulder (the coracoid) he recognized as actually being a gigantic skull bone (the quadrate). The misidentification was probably due to the quadrate's exceptionally large size as the coracoid is generally one of the larger bones in the ichthyosaur body. The implication of such a large quadrate being found was the existence a previously unknown ichthyosaur of similar or greater size to Shonisaurus itself. In life this animal may have been more than 50 feet long. He also described the new genus Leptonectes as well as the species that would later come to be known as Macgowania janiceps.
    Motani, You, and McGowan observed that the primitive ichthyosaur Chensaurus had had a relatively large number of vertebrae. This suggests that it swam in an eel-like fashion. The researchers interpreted the course of ichthyosaur evolution as starting with an eel-like body plan, transitioning to a jack-like body plan, and reaching its culmination in a tuna-like body plan.
    Dal Sasso and Pinna described the new genus and species Besanosaurus leptorhynchus.

1996年
    莫塔尼/Motani和其他学者认为鲨形超目/Selachimorpha是鱼龙类物种最好的现代参考例子，因为它们的身体结构相似。
    克里斯托弗·麦克高恩/Christopher McGowan报告了在博物馆藏品中偶然发现的一种新的巨型鱼龙物种的证据。他当时正在费城研究由美国国家科学院整理的鱼龙化石。一个来自于侏罗纪早期骨骼被编目为肩部（喙突）的一部分，他认为实际上是一块巨大的颅骨（方形）。这个错误识别可能是由于方形体的异常大，因为喙突通常是鱼龙类物种身体中较大的骨骼之一。发现如此大的方形体意味着存在一种以前未知的鱼龙类物种，其体型与秀尼龙属/Shonisaurus本身相似或更大。推测这种动物化石生前全身可能已经超过50英尺长。他还描述了新属即 纤细泳龙属/Leptonectes以及后来被重新命名为 Macgowania janiceps 的物种。
    莫塔尼/Motani、尤/You和克里斯托弗·麦克高恩/Christopher McGowan观察到原始的鱼龙类物种“Chensaurus”（现在有效属名为巢湖龙属/Chaohusaurus）的椎骨数量相对较多。这表明它以类似鳗鱼的方式游动。研究人员将鱼龙的进化过程解释为从类似鳗鱼的身体计划开始，过渡到类似杰克的身体计划，并在类似金枪鱼的身体计划中达到顶峰。
    达尔·萨索/Dal Sasso和品纳/Pinna描述了新的属和种，即贝萨诺龙属纤细喙种/Besanosaurus leptorhynchus。

1997年
    Ryosuke Motani completed his doctoral dissertation: "Phylogeny of the Ichthyosauria with Special Reference to Triassic Forms".
    Callaway argued that it was inaccurate to refer to ichthyosaurs as Ichthyopterygia.
    Callaway examined the mixosaurid fossils housed at the natural history museum in Zurich. He regarded only two species of Mixosaurus to be valid; M. cornalianus and M. atavus. He regarded M. maotaiensis, M. natans, and M. nordeskioeldii as junior synonyms of those species. He also regarded several species in the genus Phalarodon as synonymous with the two valid Mixosaurus species.
    Martin Sander of the Institute for Paleontology in Bonn named the ichthyosaur found in Karlstadt, Germany Shastasaurus neubigi in honor of its discoverer. The specimen originated in the Muschelkalk, which was deposited in a shallow sea. Because the waters were so shallow and large ichthyosaurs are so infrequently found in the Muschelkalk Sander speculated that the ichthyosaur entered the region where it would later fossilize by accident in a deviation from the normal range of the species.
    Fernández described the new genus and species Caypullisaurus bonapartei.
    Maisch and Matzke described the new genus and species Mikadocephalus gracilirostris.
    Arkhangelsky described the species that would later come to be known as Ophthalmosaurus saveljeviensis .
    Efimov described the species that would later come to be known as Platypterygius bedengensis.
    Páramo described the new species Platypterygius sachicarum

1997年
    凉介也谷/Ryosuke Motani 完成了他的博士论文：《特别参考三叠纪形态的鱼龙类系统发育》。
    卡拉威/Callaway认为，将鱼龙类物种称为鱼鳍类/Ichthyopterygia是不准确的。
    卡拉威/Callaway检查了存放在苏黎世自然历史博物馆的混合龙科动物化石。他认为只有两种混合龙是有效的； M.cornalianus 和 M. atavus。他认为 M. maotaiensis、M. natans 和 M. nordeskioeldii 是这些物种的次要同物异名。他还认为 Phalarodon 属中的几个物种是两个有效的混合龙物种的同义词。
    波恩古生物学研究所的 Martin Sander 将在德国卡尔施塔特发现的鱼龙命名为 Shastasaurus neubigi，以纪念它的发现者。该标本起源于沉积在浅海中的 Muschelkalk。由于水域很浅，而且在 Muschelkalk Sander 中很少发现大型鱼龙，因此桑德推测鱼龙进入了该地区，后来它在偏离正常物种分布范围的情况下意外进入了该地区。
    Fernández 描述了新的属和种，即Caypullisaurus bonapartei。
    Maisch 和 Matzke 描述了新的属和种/Mikadocephalus gracilirostris。
    Arkhangelsky 描述了后来被称为Saveljeviensis 眼龙的物种。
    Efimov 描述了后来被称为 Platypterygius bedenensis 的物种。
    Páramo 描述了新物种，即Platypterygius sachicarum

1998年
    Motani, Minoura, and Ando published a discussion of the ichthyosaur Utatsusaurus. They noted its primitive position in the ichthyosaur family tree and the same number of vertebrae in the front part of its body as modern catsharks. They interpreted Utatsusaurus as a maneuverable shallow water predator that swam with eel-like undulations along most of its body length.
    Maisch named the family Leptonectidae for a clade including Eurhinosaurus, Excalibosaurus, and Leptonectes. Distinguishing traits of the family include their large eyes, long flippers consisting of three or four main "digits", and their long over-biting snouts.
    Maisch and Matzke erected the genus Wimanius. The generic name honored Carl Wiman, who performed notable research on Triassic ichthyosaurs. They also named the species Wimanius odontopalatus.
    Maisch and Matzke described the new genus Contectopalatus. It had a high crest running the midlength of its cranium for jaw muscle attachment giving it a powerful bite. It also would have been about 16 feet long in life, making it twice as long as any previously discovered mixosaurid.
    Maisch erected the genus Suevoleviathan to house the species Leptopterygius disinteger.
    Darren Naish debunked the 1986 claim by Jurgen Riess that ichthyosaurs swam with their front flippers rather than their tail flukes. He concluded "if an animal has a propulsive surface on the end of its tail, it uses it."
    Efimov described the species that would later come to be known as Brachypterygius pseudoscythius.
    Brinkmann described the species that would later come to be known as Mixosaurus kuhnschnyderi.

1998年
    Motani、Minoura 和 Ando 发表了一篇关于鱼龙 Utatsusaurus 的讨论。他们注意到它在鱼龙族谱中的原始位置，其身体前部的椎骨数量与现代猫鲨相同。它的体长。
    Maisch 将 Leptonectidae 家族命名为包括 Eurhinosaurus、Excalibosaurus 和 Leptonectes 在内的一个分支。该家族的显着特征包括它们的大眼睛、由三四个主要“数字”组成的长鳍状肢，以及它们长而过咬的鼻子。
    Maisch 和 Matzke 建立了 Wimanius 属。这个属名是为了纪念 Carl Wiman，他对三叠纪鱼龙进行了著名的研究。他们还命名了 Wimanius odontopalatus。
    Maisch 和 Matzke 描述了新属 Contectopalatus。它的头骨中部有一个很高的冠，用于下颌肌肉附着，使其具有强大的咬合力。它的寿命也有大约 16 英尺，是以前的两倍长发现了混合龙科。
    Maisch 建立了 Suevoleviathan 属来容纳 Leptopterygius disinteger 物种。
    Darren Naish 驳斥了 Jurgen Riess 在 1986 年提出的鱼龙用前鳍状肢而不是尾鳍游泳的说法。他得出结论“如果动物的尾巴末端有推进表面，它就会使用它。”
    Efimov 描述了后来被称为 Brachypterygius pseudoscythius 的物种。
    Brinkmann 描述了后来被称为 Mixosaurus kuhnschnyderi 的物种。

1999年
    Ryosuke Motani published a phylogeny of the ichthyosaurs. Motani regarded Thaisaurus as "incertae sedis" due to its pronounced similarity to Chaohusaurus and how little was known about its fossils. He also erected two new genera, Macgowania (named in honor of McGowan) and Isfjordosaurus (named after Isfjord, Spitsbergen).
    The expedition to the Sikanni Chief River, British Columbia led by Elizabeth Nicholls of the Royal Tyrell Museum excavated the animal's 18 foot long skull, which had to be split into pieces for removal. These pieces were so heavy a cargo helicopter was needed to transport them. The largest weighed 8,860 lbs.
    McGowan and Motani reported the results of their re-examination of the Shonisaurus specimens described by Camp from Berlin-Ichthyosaur state park. They concluded that of the three species Camp described from among the remains, only the type and most abundant species S. popularis was valid. The other two species he named, S. silberlingi and S. mulleri, were merely junior synonyms of S. popularis.
    Motani, Rothschild, and Wahl found that Temnodontosaurus had eyes up to 10 inches in diameter, the largest known of any animal.
    Fernandez described the new ichthyosaur genus Mollesaurus from the Los Molles Formation of Argentina. He also described the species Mollesaurus periallus.
    Chun Li described the new ichthyosaur genus Qianichthyosaurus from Guizhou Province, China.
    Lingham-Soliar proposed a model for ichthyosaur extinction whereby the evolution of fishes capable of greater swimming speeds during the Cretaceous favored ambush predators like plesiosaurs and the newly evolved mosasaurs over the ichthyosaurs, who succumbed to the competition.
    McGowan and Milner described the new species Leptonectes moorei.
    Efimov described the new genus and species Undorosaurus gorodischensis. Efimov also described the species that would later come to be known as Ophthalmosaurus yasikovi.
    Li described the new genus and species Qianichthyosaurus zhoui.

1999年
    Ryosuke Motani 发表了鱼龙的系统发育。Motani 将 Thaisaurus 视为“incertae sedis”，因为它与 Chaohusaurus 有明显的相似性，并且对其化石知之甚少。他还建立了两个新属，Macgowania（以 McGowan 命名）和 Isfjordosaurus （以斯匹次卑尔根岛的伊斯峡湾命名）。
    皇家泰瑞尔博物馆的伊丽莎白·尼科尔斯 (Elizabeth Nicholls) 率领的不列颠哥伦比亚省 Sikanni Chief River 探险队挖掘了该动物 18 英尺长的头骨，必须将其拆成碎片才能移除。最大的重达 8,860 磅。
    McGowan 和 Motani 报告了他们对柏林鱼龙州立公园 Camp 描述的 Shonisaurus 标本进行重新检查的结果。他们得出结论，在 Camp 描述的三个物种中，只有 S.popularis 的类型和最丰富的物种是有效。他命名的另外两个物种，S. silberlingi 和 S. mulleri，只是 S. popularis 的初级同义词。
    Motani、Rothschild 和 Wahl 发现 Temnodontosaurus 的眼睛直径达 10 英寸，是已知的最大的动物。
    Fernandez 描述了来自阿根廷 Los Molles 组的新鱼龙属 Mollesaurus，他还描述了 Mollesaurus periallus。
    春丽描述了来自中国贵州省的鱼龙新属千鱼龙。
    Lingham-Soliar 提出了一种鱼龙灭绝模型，该模型实质上是在白垩纪期间能够以更高速度游动的鱼类的进化，它们喜欢伏击捕食者，如蛇颈龙和新进化的沧龙，而鱼龙则在竞争中屈服。
    McGowan 和 Milner 描述了新物种 Leptonectes moorei。
    Efimov 还描述了新的属和种 Undorosaurus gorodischensis. Efimov 还描述了后来被称为 Ophthalmosaurus yasikovi 的物种。
    Li 描述了新属和新种千鱼龙 zhoui。

下图为主要的鱼龙形下纲物种的化石发现者与化石研究者下