Anabaritida

Anabarites trisulcatus, from Wikimedia.

Belongs within: Trilobozoa.

From three to two
Published 23 August 2011
(I’ve been waiting three and a half years to use Neil’s icon.)

The mysterious anabaritids of the Lower Cambrian have been referred to on this site before. In the earlier, somewhat brief post, I referred to their triradial structure and uncertain, though probably coelenterate-grade, relationships. In the time since that post appeared, the anabaritids have been the subject of a review by Kouchinsky et al. (2009) that brought together a lot of the previously scattered information on these animals.

The image of an anabaritid in the previous post showed the best known species, Anabarites trisulcatus. However, this was not the only species in the group. The image just above, from Kouchinsky et al. (2009), shows another species, Anabarites biplicatus, recorded from the Siberian Platform. This species differs from A. trisulcatus in that it started out life triradial (albeit with the internal dividing ridges between the lobes only weak), but as it grew it lost its triradiality and became more bilateral (cross-section below from Kouchinsky et al.):

Some of my readers may remember that Cambrian problematica were something of a cause célèbre during the mid-90s when a lot of journals and magazines ran features on them (probably inspired to a certain degree by Stephen Jay Gould’s somewhat dreadful book Wonderful Life). In the more academic corners of this pageant, the triradiality of anabaritids (as well as some other early animals such as Tribrachidium) garnered them a certain degree of attention. It was suggested by some that they might represent a unique animal lineage that was eventually superseded by our own bilateral dynasty. However, the changing symmetry of Anabarites biplicatus serves as a reminder that we should not be too hasty to assign great significance to such features. Indeed, in the modern fauna, nematodes are partially triradial (they have a triradial head structure, with one upper and two lower lips around the mouth). Though the affinities of anabaritids are somewhat debatable, the most popular scenario is that they are related to cnidarians: their tubes bear a certain resemblance to the polyps of some medusozoans. Cnidarians also exhibit a wide variety of symmetries, such as the tetraradial organisation of scyphozoans and the hexaradial organisation of hexacorals. Without preserved soft tissue to inform us what the organisation of the inhabitant animal may have been, it is difficult to say just how much weight the triradiality of the anabaritid tube should be given.

Systematics of Anabaritida
<==Anabaritida [Angustiochreida, Angustiochreidae]
    |  i. s.: Kotujkanites Bokova 1985 [=Kotyikanites (l. c.)]KB09
    |           |--*K. sulcatus Bokova 1985 [=Anabarites sulcatus]KB09
    |           `--K. vallatus Bokova 1985KB09
    |--Cambrotubulus Missarzhevsky in Rozanov et al. 1969 [Cambrotubulidae, Cambrotubulina, Cambrotubulinae]KB09
    |    |--C. sibiricus (Val’kov 1968) (see below for synonymy)KB09
    |    `--C. corniformis Elicki 1994KB09
    `--Angustiochreina [Aculeochreidae, Anabaritidae, Anabaritinae, Lobiochreidae, Mariochreidae, Tiksithecinae]KB09
         |--Mariochrea Val’kov 1982 [incl. Gastreochrea Val’kov 1982]KB09
         |    `--*M. sinuosa Val’kov 1982 [incl. *Gastreochrea viva Val’kov 1982]KB09
         |--Selindeochrea Val’kov 1982 [Selindeochreidae]KB09
         |    |--*S. tricarinata (Missarzhevsky in Rozanov et al. 1969)KB09 (see below for synonymy)
         |    `--S. tecta Val’kov 1982KB09
         |--Aculeochrea Val’kov & Sysoev 1970 [incl. Longiochrea Val’kov & Sysoev 1970]KB09
         |    |--*A. ornata Val’kov & Sysoev 1970KB09
         |    `--A. rugosa (Val’kov & Sysoev 1970) [=*Longiochrea rugosa]KB09
         `--Anabarites Missarzhevksy in Voronova & Missarzhevsky 1969 (see below for synonymy)KB09
              |--*A. trisulcatus Missarzhevsky in Voronova & Missarzhevsky 1969 (see below for synonymy)KB09
              |--‘Angustiochrea’ aspera Vasil’eva in Bokova & Vasil’eva 1990KB09
              |--A. biplicatus (Missarzhevsky 1989) (see below for synonymy)KB09
              |--A. compositus Missarzhevsky in Rozanov et al. 1969 [=Aculeochrea composita]KB09
              |--A. convexus (Val’kov & Sysoev 1970) [=*Jakutiochrea convexa]KB09
              |--‘Tiksitheca’ curvata Fedorov in Pel’man et al. 1990KB09
              |--*Sexangulatus’ denudatus Fedorov in Pel’man et al. 1990KB09
              |--‘Tiksitheca’ fangxianensis Duan 1983KB09
              |--A. hariolus (Val’kov 1987) [=Anabaritellus hariolus]KB09
              |--A. hexasulcatus (Missarzhevsky 1974) (see below for synonymy)KB09
              |--‘Tiksitheca’ huangshandongensis Qian et al. 1979KB09
              |--‘Tiksitheca’ irregularis Qian & Ding in Ding & Qian 1988KB09
              |--A. isiticus Missarzhevksy 1974KB09
              |--A. kelleri Missarzhevksy 1989KB09
              |--A. korobovi (Missarzhevsky in Rozanov & Missarzhevsky 1966) (see below for synonymy)KB09
              |--A. latus (Val’kov & Sysoev 1970) [=*Angustiochrea lata; incl. Ang. magna Bokova 1990 (n. n.)]KB09
              |--A. licis (Missarzhevksy in Rozanov et al. 1969) [=*Tiksitheca licis]KB09
              |--‘Tiksitheca’ minuta Yue in Xing et al. 1984KB09
              |--A. missarzhevskyi (Vasil’eva 1986) [=*Udzhaites missarzhevskyi]KB09
              |--A. modestus Bokova 1985KB09
              |--A. natellus (Val’kov & Sysoev 1970) (see below for synonymy)KB09
              |--A. rarus (Fedorov 1984) [=Angustiochrea rara]KB09
              |--A. rectus Vasil’eva in Rudavskaya & Vasil’eva 1984KB09
              |--A. sexalox Conway Morris & Bengtson in Bengtson et al. 1990KB09
              |--A. signatus Mambetov in Missarzhevsky & Mambetov 1981KB09
              |--A. ternarius Missarzhevksy in Rozanov et al. 1969 [=Selindeochrea ternaria]KB09
              |--A. tripartitus Missarzhevsky in Rozanov et al. 1969 [incl. A. tribaculatus Bokova 1990 (n. n.)]KB09
              |--A. tristichus Missarzhevsky in Rozanov et al. 1969 (see below for synonymy)KB09
              |--A. trymatus Conway Morris & Bengtson in Bengtson et al. 1990KB09
              |--A. valkovi (Bokova in Bokova & Vasil’eva 1990) [=Jakutiochrea valkovi]KB09
              `--A. volutus (Missarzhevsky in Rozanov et al. 1969) [=*Kugdatheca voluta]KB09
Nomen nudum: Anabarites alvenosulcatus Bokova 1992KB09
             Cambrotubulus boroulachi Val’kov 1989KB09
             Anabarites imperceptus Bokova 1992KB09
             Angustiochrea exima Val’kov 1989KB09

Anabarites Missarzhevksy in Voronova & Missarzhevsky 1969 [incl. Anabaritellus Missarzhevksy 1974, Angustiochrea Val’kov & Sysoev 1970, Angustites Bokova 1990 (n. n.), Jakutiochrea Val’kov & Sysoev 1970, Kotuites Missarzhevksy 1989, Kugdatheca Missarzhevsky in Rozanov et al. 1969, Lobiochrea Val’kov & Sysoev 1970, Sexangulatus Fedorov in Pel’man et al. 1990, Tiksitheca Missarzhevsky in Rozanov et al. 1969, Udzhaites Vasil’eva 1986]KB09

Anabarites biplicatus (Missarzhevsky 1989) [=*Kotuites biplicatus; incl. A. bisulcatus Fedorov in Pel’man et al. 1990]KB09

Anabarites hexasulcatus (Missarzhevsky 1974) [=*Anabaritellus hexasulcatus; incl. Anabaritellus cylindriculus Qian & Ding in Ding & Qian 1988, Anabaritellus xishuiensis Qian 1977]KB09

Anabarites korobovi (Missarzhevsky in Rozanov & Missarzhevsky 1966) [=Semielliptotheca korobovi, Tiksitheca korobovi]KB09

Anabarites natellus (Val’kov & Sysoev 1970) [=*Lobiochrea natella; incl. L. formosa Bokova 1990 (n. n.), L. trialata Val’kov 1989 (n. n.)]KB09

Anabarites tristichus Missarzhevsky in Rozanov et al. 1969 [=Jakutiochrea tristicha; incl. A. gracilis Chen 1984, J. lenta Val’kov 1987, J. portentosa Val’kov 1987, J. solita Val’kov 1987]KB09

*Anabarites trisulcatus Missarzhevsky in Voronova & Missarzhevsky 1969 [incl. Ana. acuminatus Chen & Xiong in Xing et al. 1984, Ana. grandis Val’kov 1982, Ana. longissimoides Chen & Xiong in Xing et al. 1984, Ana. obliquasulcatus Qian 1978, Ana. trisulcatus f. obliquasulcatus, Angustites orbicularis Bokova 1990 (n. n.), Ana. primitivus Qian & Jiang in Luo et al. 1982, Ana. rotundum Qian 1977, Ana. rotundus, Ana. sulcoconvex Qian 1978, *Angustites trapezialis Bokova 1990 (n. n.), Ana. trisulcatus f. sulcoconvex, Ana. tenuistriatus Qian 1989, Ana. undulatus Qian 1978]KB09

*Cambrotubulus sibiricus (Val’kov 1968) [=Platysolenites sibirica; incl. C. conicus Missarzhevsky 1989, C. crassus Fedorov in Pel’man et al. 1990, *C. decurvatus Missarzhevsky in Rozanov et al. 1969, C. plicativus Val’kov 1987]KB09

*Selindeochrea tricarinata (Missarzhevsky in Rozanov et al. 1969)KB09 [=Anabarites tricarinatusKB09, Anabaritellus tricarinatusL95]

*Type species of generic name indicated

References

Kouchinsky, A., S. Bengtson, W. Feng, R. Kutygin & A. Val’kov. 2009. The Lower Cambrian fossil anabaritids: affinities, occurrences and systematics. Journal of Systematic Palaeontology 7 (3): 241-298.

Landing, E. 1995. Upper Placentian–Branchian series of mainland Nova Scotia (middle–upper Lower Cambrian): faunas, paleoenvironments, and stratigraphic revision. Journal of Paleontology 69 (3): 475-495.

Leave a comment

Your email address will not be published. Required fields are marked *