''Paleoparadoxia'' ("ancient paradox") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of large,

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

aquatic

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

s that inhabited the northern

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

coastal region during the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

epoch (). It ranged from the waters of

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

(

Tsuyama is a city in Okayama Prefecture, Japan. , the city had an estimated population of 102,294 and a population density of 200 persons per km². The total area was 185.73 km². The area increased in 2005 as the result of a merger with adjacent to ...

and

Yanagawa is a city located in Fukuoka Prefecture, Japan. As of April 30, 2011, the city has an estimated population of 71,848, with 24,507 households and a population density of 934.55 persons per km². The total area is 76.88 km². On March 21, ...

), to

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

in the north, and down to

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

Description

''Paleoparadoxia'' is thought to have fed primarily on

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of '' Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

s and

sea grass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the orde ...

es. The

jaw The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...

s and the angle of the teeth resemble a

backhoe A backhoe—also called rear actor or back actor—is a type of excavating equipment, or digger, consisting of a digging bucket on the end of a two-part articulated arm. It is typically mounted on the back of a tractor or front loader, the latt ...

bucket. Its bulky body was well adapted for swimming and underwater foraging. Originally interpreted as amphibious, ''Paleoparadoxia'' is now thought to have been a fully marine mammal like their living relatives, the

sirenians The Sirenia (), commonly referred to as sea-cows or sirenians, are an order (biology), order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The Sirenia currently compris ...

, spending most of their lives walking across the sea bottom like marine hippos. Studies on its habitat preference show that it favoured deep, offshore waters. Size estimates of ''P. tabatai'' vary, with the Tsuyama specimen measuring in length, in height, and in body mass, and the other specimens measuring and in body mass. named the genus ''Cornwallius'' but synonymized it as a species of ''Paleoparadoxia''.

References

Bibliography

* * * * * * * {{Taxonbar, from=Q2520589 Desmostylians Miocene mammals of North America Miocene mammals of Asia Miocene genus extinctions Fossils of the United States Fossil taxa described in 1959 Prehistoric placental genera Fossils of Japan Fossils of Mexico Neogene Alaska

Description

See also

References

Bibliography