Turritella
Encyclopedia
Turritella is a genus
of medium-sized sea snail
s with an operculum
, marine
gastropod mollusks in the family Turritellidae
. They have tightly coiled shells, whose overall shape is basically that of an elongated cone.
The name Turritella comes from the Latin word turritus meaning "turreted" or "towered" and the diminutive suffix -ella.
Despite its name, “Turritella agate” is not made of fossil snails of the genus Turritella. This has been realized by professionals and many amateurs for a long time, but the name (and the confusion it promotes) have persisted. The snails are actually properly referred to as Elimia tenera
, in the family Pleuroceridae
. The rock in which they are so abundant varies from a soft sandstone to a dense chalcedony. It is this dense silicified rock that is so popular with gem and mineral hobbyists, and also with purveyors of "new age" ideas such as crystal healing.
Species within the genus Turritella include:
Species brought into synonymy :
The genus is known from the Cretaceous
to the recent periods.
The shells are quite frequently found as fossil
s, and the carbonate
stone made from large quantities of Turritella shells is often referred to as "Turritella limestone", or, if silicified
, "Turritella agate". Both varieties of this stone are commonly sold as polished cabochon
s. One variety of "Turritella agate", that from the Green River Formation in Wyoming, does not in fact contain turritella, but instead has the shells of the freshwater gastropod Elimia tenera
.
The Erminger Turritellenplatte
("Turritella plate of Ermingen") near Ulm
, Germany
is a rocky outcrop
situated in the northern part of the North Alpine Foreland Basin. It is famous for its superabundance of Turritella turris shells within its sediments and dates from the Burdigalian
.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of medium-sized sea snail
Sea snail
Sea snail is a common name for those snails that normally live in saltwater, marine gastropod molluscs....
s with an operculum
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
, marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
gastropod mollusks in the family Turritellidae
Turritellidae
Turritellidae, the tower snails, is a taxonomic family of small to medium-sized sea snails, marine gastropod molluscs in the clade Sorbeoconcha.These snails are filter feeders...
. They have tightly coiled shells, whose overall shape is basically that of an elongated cone.
The name Turritella comes from the Latin word turritus meaning "turreted" or "towered" and the diminutive suffix -ella.
Species
Despite its name, “Turritella agate” is not made of fossil snails of the genus Turritella. This has been realized by professionals and many amateurs for a long time, but the name (and the confusion it promotes) have persisted. The snails are actually properly referred to as Elimia tenera
Elimia tenera
Elimia tenera, formerly known as Goniobasis tenera, is an extinct species of freshwater snails with an operculum, in the aquatic gastropod mollusk family Pleuroceridae...
, in the family Pleuroceridae
Pleuroceridae
Pleuroceridae, common name pleurocerids, is a family of small to medium-sized freshwater snails, aquatic gilled gastropod mollusks in the superfamily Cerithioidea.These snails have an operculum and typically a robust high-spired shell....
. The rock in which they are so abundant varies from a soft sandstone to a dense chalcedony. It is this dense silicified rock that is so popular with gem and mineral hobbyists, and also with purveyors of "new age" ideas such as crystal healing.
- Turritella conofasciata (Sacco 1895)
- Turritella sedanensis (Martin 1905)
- Turritella acroporaTurritella acroporaTurritella acropora is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Dall, 1889) - Turritella albolapisTurritella albolapisTurritella albolapis is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Finlay, 1924 - Turritella algidaTurritella algidaTurritella algida is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Melvill & Standen, 1912 - Turritella anactorTurritella anactorTurritella anactor is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Berry, 1957 - Turritella annulataTurritella annulataTurritella annulata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Kiener, 1843 - † Turritella apicalisTurritella apicalisTurritella apicalis is an extinct species of fossil sea snail, a marine gastropod mollusc in the family Turritellidae. These fossils are found in Florida....
- Pleistocene of Florida - Turritella attenuataTurritella attenuataTurritella attenuata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Reeve, 1849 - Turritella auricinctaTurritella auricinctaTurritella auricincta is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Martens, 1875 - Turritella aurocinctaTurritella aurocinctaTurritella aurocincta is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Martens, 1875 - Turritella bacillumTurritella bacillumTurritella bacillum is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Kiener, 1843 - † Turritella badensis - Tertiary of Denmark, Germany and Poland
- Turritella banksiiTurritella banksiiTurritella banksii is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Gray in Reeve, 1849 - Turritella bayeriTurritella bayeriTurritella bayeri is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Petuch, 2001 - Turritella bicingulataTurritella bicingulataTurritella bicingulata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Lamarck, 1822 - Turritella broderipianaTurritella broderipianaTurritella broderipiana is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
d'Orbigny, 1840 - Turritella caelata Mörch in Dunker, 1858
- Turritella capensisTurritella capensisTurritella capensis is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Krauss, 1848) - Turritella cariniferaTurritella cariniferaTurritella carinifera is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Lamarck, 1822 - Turritella chordataTurritella chordataTurritella chordata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Suter, 1908 - Turritella chrysotoxaTurritella chrysotoxaTurritella chrysotoxa is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Tomlin, 1825 - Turritella cingulataTurritella cingulataIncatella cingulata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Sowerby, 1825 - Turritella cinguliferaTurritella cinguliferaTurritella cingulifera is a species of sea snail, a marine gastropod mollusk in the family Turritellidae.It is placed either in subgenus Kurosioia or Haustator.-Distribution:...
G.B. Sowerby I, 1825 - Turritella clarionensisTurritella clarionensisTurritella clarionensis is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Hertlein & Strong, 1951 - Turritella cochleaTurritella cochleaTurritella cochlea is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Reeve, 1849 - Turritella columnarisTurritella columnarisTurritella columnaris is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Kiener, 1843 - Turritella communisTurritella communisTurritella communis is a species of medium-sized sea snails with an operculum, marine gastropod mollusks in the family Turritellidae.- Distribution and habitat :...
Risso, 1826 - Turritella concavaTurritella concavaTurritella concava is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Martens, 1880 - Turritella conspersaTurritella conspersaTurritella conspersa is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Adams & Reeve, 1850 - Turritella corneaTurritella corneaTurritella cornea is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Lamarck, 1822 - Turritella couteaudiTurritella couteaudiTurritella couteaudi is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Rochebrune & Mabille, 1889 - Turritella croceaTurritella croceaTurritella crocea is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Kiener, 1843 - † Turritella cruzadoi DeVries, 2007
- Turritella decipiensTurritella decipiensTurritella decipiens is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Monterosato, 1878 - Turritella dirkhartogensisTurritella dirkhartogensisTurritella dirkhartogensis is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Garrard, 1972) - Turritella duplicataTurritella duplicataTurritella duplicata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Linnaeus, 1758) - Turritella duraTurritella duraTurritella dura is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Mörch, 1860 - Turritella elachistaTurritella elachistaTurritella elachista is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Rochebrune & Mabille, 1889 - Turritella exoletaTurritella exoletaTurritella exoleta is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Linnaeus, 1758) - Turritella fastigiataTurritella fastigiataTurritella fastigiata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Adams & Reeve, 1850 - Turritella ferrugineaTurritella ferrugineaTurritella ferruginea is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Reeve , 1849 - Turritella fortilirataTurritella fortilirataTurritella fortilirata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
G. B. Sowerby III, 1914 - Turritella fultoniTurritella fultoniTurritella fultoni is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Melvill & Standen, 1901 - Turritella fuscomaculataTurritella fuscomaculataTurritella fuscomaculata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Bozzetti, 2009 - Turritella gemmataTurritella gemmataTurritella gemmata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Reeve, 1849 - Turritella gonostomaTurritella gonostomaTurritella gonostoma is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Valenciennes, 1832 - Turritella gracillimaTurritella gracillimaTurritella gracillima is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Gould, 1860 - Turritella hastulaTurritella hastulaTurritella hastula is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Reeve, 1849 - Turritella hookeriTurritella hookeriTurritella hookeri is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Reeve, 1849 - Turritella incisaTurritella incisaTurritella incisa is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Reeve, 1849 - † Turritella incrassata - Pliocene of Belgium
- Turritella knysnaensisTurritella knysnaensisTurritella knysnaensis is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Krauss, 1848 - Turritella leeuwinensisTurritella leeuwinensisTurritella leeuwinensis is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Garrard, 1972) - Turritella lentiginosaTurritella lentiginosaTurritella lentiginosa is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Reeve, 1849 - Turritella leucostomaTurritella leucostomaTurritella leucostoma is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Valenciennes, 1832 - Turritella ligarTurritella ligarTurritella ligar, common name : the Ligar screw shell, is a species of sea snail, a marine gastropod mollusk in the family Turritellidae.-Distribution:This species is distributed in the Atlantic Ocean along Senegal, Guinea and Gabon....
Deshayes, 1843 - Turritella lindaeTurritella lindaeTurritella lindae is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Petuch, 1987) - Turritella lyonsiTurritella lyonsiTurritella lyonsi is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Garcia, 2006 - Turritella maculataTurritella maculataTurritella maculata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Reeve, 1849 - Turritella marianopsisTurritella marianopsisTurritella marianopsis is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Petuch, 1990 - Turritella moniliferaTurritella moniliferaTurritella monilifera is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Adams & Reeve, 1850 - Turritella monterosatoi Kobelt, 1887
- Turritella nebulosaTurritella nebulosaTurritella nebulosa is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Kiener, 1843 - Turritella nodulosaTurritella nodulosaTurritella nodulosa is a species of sea snail, a marine gastropod mollusk in the family Turritellidae.-Distribution:T. nodulosa can be found in Magdalena Bay off Baja California as well as throughout the southern Gulf of California....
King & Broderip, 1832 - Turritella praetermissaTurritella praetermissaTurritella praetermissa is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Dautzenberg, 1912) - Turritella punctataTurritella punctataTurritella punctata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Kiener, 1843 - Turritella radulaTurritella radulaTurritella radula is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Kiener, 1843 - † Turritella riverae DeVries, 2007
- Turritella rubescensTurritella rubescensTurritella rubescens is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Reeve, 1849 - † Turritella salasi DeVries, 2007
- Turritella sanguineaTurritella sanguineaTurritella sanguinea is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Reeve, 1849 - † Turritella steiningeri Harzhauser, 2007
- Turritella terebraTurritella terebraTurritella terebra is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Linnaeus, 1758) - † Turritella terebralis Lamarck, 1799
- Turritella torulosaTurritella torulosaTurritella torulosa is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Kiener, 1843 - † Turritella trempina - Pliocene
- Turritella triplicataTurritella triplicataTurritella triplicata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Philippi, 1836 - Turritella turbonaTurritella turbonaTurritella turbona is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Monterosato, 1877 - † Turritella turris - Early Miocene of Central Europe
- Turritella ungulinaTurritella ungulinaTurritella ungulina is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Linnaeus, 1758) - Turritella variegataTurritella variegataTurritella variegata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Linnaeus, 1758) - Turritella vermicularisTurritella vermicularisTurritella vermicularis is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Brocchi, 1814) - † Turritella vertebroides Morton, 1834 - Late Cretaceous of South of North America
- Turritella wareniTurritella wareniTurritella wareni is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
Ryall & Vos, 2010 - Turritella willettiTurritella willettiTurritella willetti is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
McLean, 1970 - Turritella yucatecanaTurritella yucatecanaTurritella yucatecana is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Dall, 1881)
Species brought into synonymy :
- Turritella (Torcula) Gray, 1847 : synonym of Turritella Lamarck, 1799
- Turritella acicula Stimpson, 1851: synonym of Turritellopsis stimpsoni (Dall, 1919)
- Turritella alternata Say, 1822 : synonym of Bittiolum alternatumBittiolum alternatumBittiolum alternatum is a species of sea snail, a marine gastropod mollusk in the family Cerithiidae....
(Say, 1822) - Turritella aquila Reeve, 1849 : synonym of Turritella conspersa Adams & Reeve, 1850
- Turritella areolata Stimpson, 1851 : synonym of Tachyrhynchus reticulatusTachyrhynchus reticulatusTachyrhynchus reticulatus is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Mighels & Adams, 1842) - Turritella bicolor Adams & Reeve, 1850 : synonym of Turritella cingulifera G.B. Sowerby I, 1825
- Turritella brevialis Lamarck, 1822 : synonym of Mesalia brevialisMesalia brevialisMesalia brevialis is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Lamarck, 1822) - Turritella canaliculata Adams & Reeve, 1850 : synonym of Turritella cinguliferaTurritella cinguliferaTurritella cingulifera is a species of sea snail, a marine gastropod mollusk in the family Turritellidae.It is placed either in subgenus Kurosioia or Haustator.-Distribution:...
G.B. Sowerby I, 1825 - Turritella candida Reeve, 1849 : synonym of Turritella gemmata Reeve, 1849
- Turritella cingulata Sowerby, 1825 is a synonym of Incatella cingulata (Sowerby, 1825)
- Turritella concava Say, 1826 : synonym of Terebra concavaTerebra concavaTerebra concava is a species of sea snail, a marine gastropod mollusk in the family Terebridae, the auger snails....
(Say, 1826) - Turritella congelata Adams & Reeve, 1850 : synonym of Colpospira congelataColpospira congelataColpospira congelata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Adams & Reeve, 1850) - Turritella costulata Mighels & Adams, 1842 : synonym of Acirsa borealis (Lyell, 1841)
- Turritella erosa Couthouy, 1838 : synonym of Tachyrhynchus erosusTachyrhynchus erosusTachyrhynchus erosus, common name the eroded turretsnail, is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Couthouy, 1838) - Turritella eschrichti Hölböll in Möller, 1842 : synonym of Acirsa borealis (Lyell, 1841)
- Turritella flammulata Kiener, 1843-44 : synonym ofTurritella ligar Deshayes, 1843
- Turritella granosa Quoy & Gaimard, 1834 : synonym of Opalia granosa (Quoy & Gaimard, 1834)
- Turritella imbricata (Linnaeus, 1758) : synonym of Turritella variegata (Linnaeus, 1758)
- Turritella lactea Möller, 1842 : synonym of Mesalia lacteaMesalia lacteaMesalia lactea is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Möller, 1842) - Turritella maiquetiana Weisbord, 1962 † : synonym of Turritella paraguanensis Hodson, 1926
- Turritella meta Reeve, 1849 : synonym of Turritella gemmataTurritella gemmataTurritella gemmata is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
- Turritella minuta Turton, 1932 : synonym of Teretianax minuta (Turton, 1932)
- Turritella monterosatoi Kobelt, 1887 : synonym of Turritella turbona Monterosato, 1877
- Turritella nzimaorum Ryall & Vos, 2010 : synonym of Turritella caelata Mörch in Dunker, 1858
- Turritella opalina Adams & Reeve, 1850 : synonym of Mesalia opalina (Adams & Reeve, 1850)
- Turritella opulenta Hedley, 1907 : synonym of Glyptozaria opulentaGlyptozaria opulentaGlyptozaria opulenta is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Hedley, 1907) - Turritella paraguanensis Hodson, 1926 : synonym of Turritella variegata (Linnaeus, 1758)
- Turritella philippi Aradas, 1842 : synonym of Acirsa subdecussata (Cantraine, 1835)
- Turritella polaris Möller, 1842 : synonym of Tachyrhynchus erosusTachyrhynchus erosusTachyrhynchus erosus, common name the eroded turretsnail, is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Couthouy, 1838) - Turritella reticulata Mighels & Adams, 1842 : synonym of Tachyrhynchus reticulatusTachyrhynchus reticulatusTachyrhynchus reticulatus is a species of sea snail, a marine gastropod mollusk in the family Turritellidae....
(Mighels & Adams, 1842) - Turritella spirata Sowerby I, 1825 : synonym of Eglisia spirata (Sowerby I, 1825)
- Turritella symmetrica Hutton, 1873: synonym of Stiracolpus symmetricusStiracolpus symmetricusStiracolpus symmetricus, common name : the small turret, is a species of sea snail, a marine gastropod mollusk in the family Turritellidae.-References:* -External links:*...
(Hutton, 1873) - Turritella trisulcata Lamarck, 1822 : synonym of Turritella vermicularis
- Turritella yucatecanum Dall, 1881 : synonym of Turritella yucatecana (Dall, 1881)
Fossil species
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
to the recent periods.
The shells are quite frequently found as fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s, and the carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
stone made from large quantities of Turritella shells is often referred to as "Turritella limestone", or, if silicified
Silicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...
, "Turritella agate". Both varieties of this stone are commonly sold as polished cabochon
Cabochon
A cabochon , from the Middle French caboche , is a gemstone which has been shaped and polished as opposed to faceted. The resulting form is usually a convex top with a flat bottom. Cutting en cabochon is usually applied to opaque gems, while faceting is usually applied to transparent stones...
s. One variety of "Turritella agate", that from the Green River Formation in Wyoming, does not in fact contain turritella, but instead has the shells of the freshwater gastropod Elimia tenera
Elimia tenera
Elimia tenera, formerly known as Goniobasis tenera, is an extinct species of freshwater snails with an operculum, in the aquatic gastropod mollusk family Pleuroceridae...
.
The Erminger Turritellenplatte
Turritellenplatte
The Turritellenplatte of Ermingen is a type of very rich fossil-bearing rock which is of particular interest to geologists and paleontologists...
("Turritella plate of Ermingen") near Ulm
Ulm
Ulm is a city in the federal German state of Baden-Württemberg, situated on the River Danube. The city, whose population is estimated at 120,000 , forms an urban district of its own and is the administrative seat of the Alb-Donau district. Ulm, founded around 850, is rich in history and...
, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
is a rocky outcrop
Outcrop
An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. -Features:Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be...
situated in the northern part of the North Alpine Foreland Basin. It is famous for its superabundance of Turritella turris shells within its sediments and dates from the Burdigalian
Burdigalian
The Burdigalian is, in the geologic timescale, an age or stage in the early Miocene. It spans the time between 20.43 ± 0.05 Ma and 15.97 ± 0.05 Ma...
.