科学家发现了保存极其完好的200多只虾化石，这些虾是在大约9500万年前的一次“大规模死亡”事件中被杀死的。这些虾是在现在的哥伦比亚的一个排水口寻找雌性伴侣时被杀死的。保存水平意味着研究人员能够看到这些古代生物最精细的解剖细节，包括它们的眼睛、嘴巴和毛发。
逗号虾化石是在白垩纪中期的岩石中发现的。它们估计在9000万到9500万年前——那时恐龙还在地球上行走。
逗号虾——也称为cuma acea——是小型甲壳类动物，如今在全球海洋环境中都能发现，其种类超过1000种。
然而，尽管它们很丰富，但它们却是所有海洋节肢动物中最差的化石记录之一，所以我们对它们起源的了解有限。
在发表于皇家学会学报乙:生物科学来自阿拉斯加安克雷奇大学的耶鲁大学的哈维尔·卢克和莎拉·格肯宣布发现了一群古老的逗号虾祖先，它们具有“非凡的保存能力”，有助于填补超过1.6亿年的虾化石记录。
人们发现这块岩石有200多个人，长0.2到03英寸。大多数被发现有“大而明显的触角鞭毛”——这是雄性的特征。只有少数女性，根本没有青少年，研究人员称这是“非凡的”
卢克和格肯注意到，现代逗号虾在夜间聚集在水柱中寻找配偶。他们相信这些古老的虾在寻找雌性时，发生了一些事情导致它们全部死亡。然后，它们轻轻地漂流到它们下面的水洼里，在那里它们会被保存在柔软的沉积物中。
研究人员称，这些被命名为Eobodotria muisca的虾代表“迄今为止报道的第一个也是最古老的明确化石皇冠cumacean”。
最后，他们说，这一发现表明逗号虾这一特定家族出现在白垩纪中期，甚至可能更早。“我们的发现填补了真正逗号虾进化过程中超过1.6亿年的空白，并为cumacean的分子和形态学研究提供了可靠的校准点...研究称。
“虽然我们对逗号虾的起源和关系的理解还远未确定，但这些发现提供了关于皇冠紫锥菊早期进化和紫锥菊分支分化时间的假说。”
虾化石的典型图像。研究人员发现了大约200个逗号虾化石，其中大多数是雄性。
HUNDREDS OF DOOMED SHRIMP THAT DIED WHILE LOOKING FOR FEMALES DISCOVERED PERFECTLY PRESERVED AFTER 95 MILLION YEARS
The extremely well preserved fossils of over 200 shrimp killed in a "mass mortality" event around 95 million years ago has been discovered by scientists. The shrimp were killed while searching for females to mate with in a water vent in what is now Columbia. The level of preservation means researchers were able to see the finest anatomical details of these ancient creatures, including their eyes, mouths and hairs.
The comma shrimp fossils were found in a rock from the mid-Cretaceous period. They are estimated to be between 90 and 95 million years ago—when the dinosaurs still walked the Earth.
Comma shrimp—also known as cumacea—are small crustaceans that today are found in marine environments across the globe, with well over 1,000 species within the order.
However, despite their abundance they have one of the poorest fossil records of any marine arthropods, so our understanding of their origins has been limited.
In a study published in the Proceedings of the Royal Society B: Biological Sciences, Yale's Javier Luque and Sarah Gerken from the University of Alaska Anchorage have announced the discovery of a swarm of ancient comma shrimp ancestors with "exceptional preservation" that helps fill in over 160 million years of the shrimp fossil record.
The rock was found to contain over 200 individuals measuring between 0.2 and 03 inches in length. Most were found to have "large and conspicuous antennal flagella"—a feature characteristic of males. There were just a few females and no juveniles at all, something the researchers say is "remarkable."
Luque and Gerken note that modern comma shrimp are known to congregate at night in water columns while looking for mates. They believe these ancient shrimp were in search of females when something happened that caused them all to die. They then gently drifted down to their watery grave below, where they would be preserved in the soft sediment.
The researchers say these shrimp, which have been named Eobodotria muisca, represent "the first and oldest unambiguous fossil crown cumacean reported to date."
Concluding, they said the discovery shows this specific family of comma shrimp were present by the mid-Cretaceous period, and potentially even earlier. "Our findings bridge a gap of more than 160 million years in the evolution of true comma shrimp, and provides a reliable calibration point for molecular and morphological studies of the cumacean...trees of life," the study says.
"Although our understanding of the origins and relationships of comma shrimp are far from settled, these findings provide hypotheses about the early evolution of crown Cumacea and the timing of divergence of the cumacean clade."
Representative image of a fossilized shrimp. Researchers found around 200 comma shrimp fossils, with most being male.
