Ectopharyngeata and Endopharyngeata instead of Protostomia and Deuterostomia?

The use of molecular phylogenetic methods has caused a profound rearrangement of the system and phylogeny of the triploblastic Bilateria (=Triploblastica). Nevertheless, in most phylogenetic trees, two main clades remain, coinciding with Protostomia and Deuterostomia, established by K. Grobben (1908) more than 100 years ago. For both clades of Triploblastica, amphistomy is the primary way of forming a through intestine. However, the analysis shows that only the origin of the mouth and anus does not allow us to distinguish between the two main clades. All the groups that were referred to Grobben’s Protostomia are characterized by an ectodermal pharynx, therefore this clade would be more correctly called Ectopharyngeata. Based on the modification of the pharyngeal cuticle, many ectopharyngeates develop various structures designed to grind food. The groups attributed by K. Grobben to Deuterostomia have an endodermal pharynx, therefore it would be more correct to call this clade Endopharyngeata. The synapomorphy of Endopharyngeata is the development of gill slits in the walls of the endodermal pharynx and the division of the pharynx into two zones – the dorsal branchial zone, and ventral digestive zone. During the evolution of the chordates, the sides of the body were inverted. As a result, that part of the digestive tube, which is homologous to the hemichordate digestive zone of the pharynx, became the dorsal notochord and the branchial zone of the pharynx turned out to be ventral. Thus, the division of Triploblastica into two clades entirely retains its significance in modern biology, although it is based on a different set of morphological features than that considered by K. Grobben.

1. Grobben K. Die systematische Einteilung des Tier­reiches. Verh. kaiser.-könig. zool.-bot. Ges. Wien. 1908;58(10):491–511.

2. Malakhov V.V. A new system of Bilateria. Her. Russ. Acad. Sci. 2010;80(3):29–41. DOI: 10.1134/S1019331610010041

3. Malakhov V.V. A revolution in zoology: New concepts of the metazoan system and phylogeny. Her. Russ. Acad. Sci. 2013;83(2):123–127. DOI: 10.1134/S1019331613020044

4. Halanych K.M., Bacheller J.D., Aguinaldo A.M., Liva S.M., Hillis D.M., Lake J.A. Evidence from 18S ribosomal DNA that the lophophorates are protostome animals. Science. 1995;267(5204):1641–1643. DOI: 10.1126/science.7886451

5. Halanych K.M., Dahlgren T.G., McHugh D. Unseg­mented annelids? Possible origins of four lophotrochozoan worm taxa. Integr. Comp. Biol. 2002;42(3):678–684. DOI: 10.1093/icb/42.3.678

6. Aguinaldo A.M., Turbeville J.M., Linford L.S., Rive­ra M.C., Garey J.R., Raff R.A., Lake J.A. Evidence for a clade of nematodes, arthropods and other moulting animals. Nature. 1997;387(6632):489–493. DOI: 10.1038/387489a0

7. de Rosa R., Grenier J.K., Andreeva T., Cook C.E., Adoutte A., Akam M., Carroll S.B., Balavoine G. Hox genes in brachiopods and priapulids and protostome evolution. Nature. 1999;399(6738):772–776. DOI: 10.1038/21631

8. Halanych K.M. The new view of animal phylogeny. Annu. Rev. Ecol. Evol. Syst. 2004;35:229–256. DOI: 10.1146/annurev.ecolsys.35.112202.130124

9. Dunn C.W., Hejnol A., Matus D.Q. et al. Broad phy­logenomic sampling improves resolution of the animal tree of life. Nature. 2008;452(7178):745–750. DOI: 10.1038/nature06614

10. Dunn C.W., Giribet G., Edgecombe G.D., Hejnol A. Animal phylogeny and its evolutionary implications. Annu. Rev. Ecol. Evol. Syst. 2014;45:71–395. DOI: 10.1146/annurevecolsys-120213-091627

11. Giribet G. New animal phylogeny: future challenges for animal phylogeny in the age of phylogenomics. Annu. Rev. Ecol. Evol. Syst. 2015;45:371–395. DOI: 10.1007/s13127-015-0236-4

12. Telford M., Budd G., Philippe H. Phylogenomic in­sights into animal evolution. Curr. Biol. 2015;25(19):876–887. DOI: 10.1016/j.cub.2015.07.060

13. Laumer C.E., Fernández R., Lemer S., Com­bosch D., Kocot K.M., Riesgo A., Andrade S.C.S., Ster­rer W., Sørensen M.V., Giribet G. Revisiting metazoan phy­logeny with genomic sampling of all phyla. Proc. Biol. Sci. 2019;286(1906):20190831. DOI: 10.1098/rspb.2019.0831

14. Малахов В.В. Проблемы построения общей системы многоклеточных. Современная эволюционная морфология. Под ред. Э.И. Воробьевой. Киев: Наукова думка; 1991:195–213.

15. Hejnol A., Martindale M.Q. The mouth, the anus, and the blastopore – open questions about questionable openings. Ani­mal Evolution: Genomes, Fossils, and Trees. Eds. Telford M. J., and Littlewood D.T.J. Oxford: Oxford Academic; 2009:33–40.

16. Nielsen C. How to make a protostome. Invertebrate Systematics. 2012;26(1):25–40. DOI: 10.1071/IS11041

17. Nielsen C. Evolution of deuterostomy and origin of the chordates. Biol. Rev. Camb. Philos. Soc. 2015;92(1):316–325. DOI: 10.1111/brv.12229

18. Nielsen C., Brunet T., Arendt D. Evolution of the bila­terian mouth and anus. Nat. Ecol. Evol. 2018;2(9):1358–1376. DOI: 10.1038/s41559-018-0641-0

19. Nielsen C. Blastopore Fate: Amphistomy, Protosto­my or Deuterostomy. eLS. Chichester: John Wiley & Sons Ltd.; 2019:1–8. DOI: 10.1002/9780470015902.a0027481

20. Ivanova-Kazas O.M. The secondary mouth and its phylogenetic significance. Russ. J. Mar. Biol. 2015;41(1):83–93. DOI: 10.1134/S1063074015020054.

21. Martín-Durán J.M., Passamaneck Y.J., Martin­dale M.Q., Hejnol A. The developmental basis for the recur­rent evolution of deuterostomy and protostomy. Nat. Ecol. Evol. 2016;1(1):5. DOI: 10.1038/s41559-016-0005

22. Tagawa K., Nishino A., Humphreys T., Satoh N. The spawning and early development of the Hawaiian acorn worm (Hemichordate), Ptychodera flava. Zool. Sci. 1998;15(1):85–91. DOI: 10.2108/zsj.15.85

23. Miyamoto N., Saito Y. Morphology and develop­ment of a new species of Balanoglossus (Hemichordata: En­teropneusta: Ptychoderidae) from Shimoda. Zool. Sci. 2007;24(12):1278–1285. DOI: 10.2108/zsj.24.1278

24. Akesson B. The embryology of the polychaete Eu­nice kobiensis. Acta Zoologica. 1967;48(1–2):141–192. DOI: 10.1111/j.1463-6395.1967.tb00136.x

25. Dautert E. Die Bildung der Kaimblatter bei Paludi­na. Zool. Jb. Abt. Anat. 1926;50(4):433–496.

26. Zilch R. Embryologische Untersuchungen an der holoblastischen Ontogenese von Penaeus trisulcatus Leach (Crustacea, Decapoda). Zoomorphologie. 1978;90(1):67–100.

27. Martín-Durán J.M., Janssen R., Wennberg S., Budd G.E., Hejnol A. Deuterostomic development in the pro­tostome Priapulus caudatus. Curr. Biol. 2012;22(22):2161–2166. DOI: 10.1016/j.cub.2012.09.037

28. Малахов В.В., Спиридонов С.Э. Эмбриональ­ное развитие Gordius sp. из Туркмении с обсуждением положения волосатиков в системе животного царства. Зоол. журн. 1984;63(9):1285–1296.

29. Balfour F.M. Anatomy and development of Peri­patopsis capensis. Quart. J. Micr. Soc. 1883;23(2):213–259.

30. Sedgwick A. The development of Peripatus capensis. Part I. Quart. J. Micr. Soc. 1885;25(4):449–466.

31. Malakhov V.V. Nematodes. Structure, Development, Classification, Phylogeny. Washington and London: Smithso­nian Institution Press; 1994. 286 pp.

32. Malakhov V.V. Embryological and histological pe­culiarities of the order Enoplida, a primitive group of nema­todes. Russ. J. Nematol. 1998;6(1):41–46.

33. de Beauchamp P.M. La development des Gastro­triches. Bull. Soc. Zool. France. 1929;54(5):549–558.

34. Teuchert G. Zur Fortpflanzung und Entwicklung der Macrodasyoidea (Gastrotricha). Z. Morphol. Tiere. 1968;63(2):343–418.

35. Treadwell A.L. The cytogeny of Podarke obscura. J. Morphol. 1901;17(2):399–476.

36. Woltereck R. Trochophorastudien. 1. Ueber die En­twicklung des Annelids bei den Polygordiusarten der Nord­see. Bibliotheca Zoologica (Stuttgart). 1902;34:1–71.

37. Shearer C. The development of the trochophore of Hydroides (Eupomatus) uncinatus. Quart. J. Microsc. Sci. 1911;56(2):543–590.

38. Akesson В. The embryology of Tomopteris helgo­landicus (Polychaeta). Acta Zoologica. 1962;48(1):135–199.

39. Adrianov A.V., Mayorova A.S., Malakhov V.V. Embry­onic development of the peanut worm Themiste pyroides (Sipun-cula: Sipunculoidea) from the Sea of Japan. Invertebr. Reprod. Dev. 2008;52(1):143–151. DOI: 10.1080/07924259.2008.9652282.

40. Patten W. The embryology of Patella. Arb. Zool. Inst. Univ. Wien und Zool. Stat. Triest. 1886;6(2):149–174.

41. Conklin E.G. The embryology of Crepidula. J. Mor­phol. 1897;13(1):1–226.

42. Heath H. The development of Ischnochiton. Zool. Jb. Abt. Anat. 1898;12(2):567–565.

43. Малахов В.В., Медведева Л.А. Эмбриональное развитие двустворчатого моллюска Mytilus edulis (Mytili­da, Mytilidae). Зоол. журн. 1985;64(12):1808–1815.

44. Lartillot N., Lespinet O., Vervoort M., Adoutte A. Expression pattern of Brachyury in the mollusk Patella vul­gate suggests a conserved role in the establishment of the AP axis in Bilateria. Development. 2002;129(6):1411–1421. DOI: 10.1242/dev.129.6.1411

45. Lyons D.C., Perry K.J., Henry J.Q. Spiralian gas­trulation: germ layer formation, morphogenesis, and fate of the blastopore in the slipper snail Crepidula fornicate. EvoDe­vo. 2015;6:24. DOI:10.1186/s13227-015-0019-1

46. Rattenbury J. C. The embryology of Phoronopsis viridis. J. Morph. 1954;95(2):289–349.

47. Temereva E.N., Malakhov V.V. Embryogenesis and larval development of Phoronopsis harmeri Pixell, 1912 (Phoro­nida): dual origin of the coelomic mesoderm. Invertebr. Reprod. Dev. 2007;50(2):57–66. DOI: 10.1080/07924259.2007.9652228.

48. Marcus E. Briozoários marinhos brasileiros. 3. Bo­letins da Faculdade de Filosofia, Ciências e Letras. Univ. San Paulo. Zool. 1939;3(1):111–299.

49. Малахов В.В. Описание развития Ascopodaria discreta (Coloniales, Barentsiidae) и обсуждение положе­ния Kamptozoa в системе животного царства. Зоол. журн. 1990;69(10):20–30.

50. Conklin E.G. The embryology of a brachiopod, Terebratulina septentrionalis Couthouy. Proc. Am. Philos. Soc. 1902;41(1):41–76.

51. Martín-Durán J., Passamaneck Y., Martindale M., Hejnol A. The developmental basis for the recurrent evolu­tion of deuterostomy and protostomy. Nat. Ecol. Evol. 2016;1(1):5. DOI: 10.1038/s41559-016-0005

52. Ковалевский А.О. Наблюдения над развитием Вгасhiороdа. Изв. Имп. О-ва любит. естествозн., антро­пол. этногр. 1874;14(1):1–40.

53. Nielsen C. The development of the brachiopod Cra­nia (Neocrania) anomala (O.F. Müller) and its phylogenetic significance. Acta Zool. 1991;72(1):7–28. DOI: 10.1111/j.1463-6395.1991.tb00312.x

54. Vellutini B.C., Hejnol A. Expression of segment po­larity genes in brachiopods supports a non-segmental ances­tral role of engrailed for bilaterians. Sci. Rep. 2016;6:32387. DOI: 10.1038/srep32387

55. Heymons R. Die Entwicklungsgeschichte der Scol­opender. Bibliotheca Zoologica (Stuttgart). 1901;13:1–224.

56. Иванов П.П. Эмбриональное развитие сколо­пендры в связи с эмбриологией и морфологией Trachea­ta. Изв. АН СССР. Отдел. биолог. наук. 1940;6:831–861.

57. Wheeler W.M. A contribution to insect embryology. J. Morphol. 1893;8(1):1–161.

58. Jura C. Embryogenesis of the alimentary system of the weevil, Phyllobius glaucus. Zool. Poloniae. 1956;7(1):155–176.

59. Brauer A. Entwicklungsgeschichte des Scorpions. Z. wiss. Zool. 1894;57(2):409–432.

60. Weygoldt P. Embryologische Untersuchungen an Ostracoden: Die Entwicklung von Cyprides litoralis. Zool. Jb. Abt. Anat. 1960;78(2):370–426.

61. Nielsen C., Hay-Schmidt A. Development of the enteropneust Ptychodera flava: ciliary bands and nervous system. J. Morphol. 2007;268(7):551–570. DOI: 10.1002/jmor.10533

62. Малахов В.В. Проблема основного плана строе­ния в различных группах вторичноротых животных. Журн. общ. биологии. 1977;38(4):485–499.

63. Arendt D., Nübler-Jung K. Inversion of dorsoven­tral axis. Nature. 1994;371(6492):26. DOI: 10.1038/371026a0

64. Arendt D., Nübler-Jung K. Dorsal or ventral: simi­larities in fate maps and gastrulation patterns in annelids, ar­thropods and chordates. Mech. Dev. 1997;61(1–2):7–21. DOI: 10.1016/s0925-4773(96)00620-x

65. MacBride E. W. The formation of the layers in am­phioxus and its bearing on the interpretation of the early on­togenetic processes in other vertebrates. Quart. J. Microsc. Sci. 1909;54(3):279–345.

66. Bergström J. Origin of high-rank groups of organ­isms. Paleontol. Res. 1997;1(1):1–14.

67. Nübler-Jung K.N., Arendt D. Dorsoventral axis in­version. Enteropneust anatomy links invertebrates to chor­dates turned upside down. J. Zool. Syst. Evol. Res. 1999;37(2):93–100.

68. Lacalli T.C. The emergence of the chordate body plan: some puzzles and problems. Acta Zoologica (Stockholm). 2010;91(1):4–10. DOI: 10.1111/j.1463-6395.2008.00384.x

69. Veeman M.T., Newman-Smith E., El-Nachef D., Smith W.C. The ascidian mouth opening is derived from the anterior neuropore: reassessing the mouth/neural tube relation­ship in chordate evolution. Dev. Biol. 2010;344(1):138–149. DOI: 10.1016/j.ydbio.2010.04.028

70. Максимов А.А. Основы гистологии. Петроград: К.Л. Риккер; 1914. 382 с.

71. Jiménez A.J., Domínguez-Pinos M.D., Guer­ra M.M., Fernández-Llebrez P., Pérez-Fígares J.M. Struc­ture and function of the ependymal barrier and diseases as­sociated with ependyma disruption. Tissue Barriers. 2014;2:e28426. DOI: 10.4161/tisb.28426

72. Denes A.S., Jékely G., Steinmetz P.R., Raible F., Sny­man H., Prud’homme B., Ferrier D.E., Balavoine G., Arendt D. Molecular architecture of annelid nerve cord supports com­mon origin of nervous system centralization in bilateria. Cell. 2007;129(2):277–288. DOI: 10.1016/j.cell.2007.02.040

73. Arenas-Mena C. Brachyury, Tbx2/3 and sall expres­sion during embryogenesis of the indirectly developing poly­chaete Hydroides elegans. Int. J. Dev. Biol. 2013;57(1):73–83. DOI: 10.1387/ijdb.120056ca

74. Lauri A., Brunet T., Handberg-Thorsager M., Fis­cher A.H., Simakov O., Steinmetz P.R., Tomer R., Keller P.J., Arendt D. Development of the annelid axochord: insights into notochord evolution. Science. 2014;345(6202):1365–1368. DOI: 10.1126/science.1253396

75. Boyle M.J., Yamaguchi E., Seaver E.C. Molecular conservation of metazoan gut formation: evidence from ex­pression of endomesoderm genes in Capitella teleta (Anneli­da). EvoDevo. 2014;5:39. DOI: 10.1186/2041-9139-5-39

76. Martín-Durán J. M., Hejnol A. The study of Pria­pulus caudatus reveals conserved molecular patterning un­derlying different gut morphogenesis in the Ecdysozoa. BMC Biol. 2015;13:29. DOI: 10.1186/s12915-015-0139-z

77. Arendt D., Technau U., Wittbrodt J. Evolution of the bilaterian larval foregut. Nature. 2001;409(6816):81–85. DOI: 10.1038/35051075

78. Tagawa K., Humphreys T., Satoh N. Novel pattern of Brachyury gene expression in hemichordate embryos. Mech. Dev. 1998;75(1–2):139–143. DOI: 10.1016/s0925-4773(98)00078-1

79. Shoguchi E., Satoh N., Maruyama Y.K. Pattern of Brachyury gene expression in starfish embryos resembles that of hemichordate embryos but not of sea urchin embryos. Mech. Dev. 1999;82(1–2):185–189. DOI: 10.1016/s0925-4773(99)00008-8

80. Davidson A.J., Zon L.I. The caudal-related homeo­box genes cdx1a and cdx4 act redundantly to regulate hox gene expression and the formation of putative hematopoietic stem cells during zebrafish embryogenesis. Dev. Biol. 2006;292(2):506–518. DOI: 10.1016/j.ydbio.2006.01.003

81. Mudumana S.P., Hentschel D., Liu Y., Vasilyev A., Drummond I.A. odd skipped related1 reveals a novel role for endoderm in regulating kidney versus vascular cell fate. Deve-lopment. 2008;135(20):3355–3367. DOI: 10.1242/dev.022830

82. Hejnol A., Martindale M. Acoel development indi­cates the independent evolution of the bilaterian mouth and anus. Nature. 2008;456(7220):382–386. DOI: 10.1038/nature07309

83. Andrikou C., Pang K., Børve A., Lu T-M., He­jnol A. Molecular evidence from xenacoelomorph gonopore formation supports homology with the bilaterian anus. Nat. Ecol. Evol. 2025;9:2116–2126. DOI: 10.1038/s41559-025-02866-6

84. Marlétaz F., Peijnenburg K.T.C.A., Goto T., Sa­toh N., Rokhsar D.S. A new spiralian phylogeny places the enigmatic arrow worms among gnathiferans. Curr. Biol. 2019;29(2):312–318. DOI: 10.1016/j.cub.2018.11.042

85. Piovani L., Gavriouchkina D., Parey E., Sarre L.A., Peijnenburg K.T.C.A., Martín-Durán J.M., Rokhsar D.S., Satoh N., de Mendoza A., Goto T., Marlétaz F. The geno-mic origin of the unique chaetognath body plan. Nature. 2025;645(8082):964–973. DOI: 10.1038/s41586-025-09403- 2. DOI: 10.1038/s41586-025-09403-2

86. Lankaster E.R. On the use of the term homology in modern zoology, and the distinction between homogenetic and homoplastic agreements. Ann. Mag. Nat. Hist. 1870;6(31):34–43.

87. Любищев А.А. Понятие сравнительной анатомии. В кн.: Вопросы общей зоологии и медицинской паразитологии. М.: Биомедгиз; 1962:189–214.

88. Beklemishev V.N. Principles of comparative anatomy of invertebrates: V. 1 Promorphology, vol. 2 Organology. Univ. Chicago Press; 1969. 1058 pp.

89. Иванов Д.Л., Цетлин А.Б. Возниковение и эво­люция кутикулярного глоточного вооружения у трохо­форных животных с вентральной глоткой. Зоол. журн. 1981;60(11):1445–1454.

90. Tzetlin A., Purschke G. Pharynx and intestine. Hy­drobiologia. 2005;535/536(1):199–225. DOI: 10.1007/1-4020-3240-4_12

91. Remane A. Die Grundlagen des natürlichen Systems der vergleichenden Anatomie und der Phylogenetik. Leipzig; 1952. 400 S.

92. Spengel J.W. Die Enteropneusten des Golfes von Ne­apel und der angrenzenden Meeres-Abschnitte. Fauna und Flo­ra des Golfes von Neapel und der angrenzenden Meeres-Ab­schnitte. Herausgegeben von der Zoologischen Station zu Neapel. Berlin: Friedländer. 1893;18:1–757.

93. van der Horst C.J. Hemichordata. Klassen und Ord­nungen des Tierreichs wissenschaftlich dargestellt in Wort und Bild. Ed. Bronn H.G. Leipzig: Akademische Verlags­gesellschaft; 1939: 1–737.

94. Barrington E.J.W. Observations on feeding and di­gestion in Glossobalanus minutus. Quart. J. Micr. Sci. 1940;82(2):227–260.

95. Burdon-Jones C. The feeding mechanism of Bal­anoglossus gigas. Bol. Fac. Filos. Cienc. Letr. Univ. Sao Paulo. Zoologia.1962;24(261):255–280.

96. Cameron C.B. Particle retention and flow in the phar­ynx of the enteropneust worm Harrimania planktophilus: the fil­ter-feeding pharynx may have evolved before the chordates. Biol. Bull. 2002;202(2):192–200. DOI: 10.2307/1543655

97. Slack J.M.W., Holland P.W.H., Graham C.F. The zootype and the phylotypic stage. Nature. 1993;361(6412):490–492. DOI: 10.1038/361490a0

98. Ruppert E.E., Cameron C.B., Frick J.E. Endo­style-like features of the dorsal epibranchial ridge of an en­teropneust and the hypothesis of dorso-ventral inversion in chordates. Invert. Biol. 1999;118(2):202–212. DOI: 10.2307/3227061

99. Sato T. Vorlaufige mitteilung fiber Atubaria heterolo­pha gen. nov., sp. nov., einen in freiem zustand aufgefunde­nen Pterobranchier aus dem stillen ozean. Zoologische An­zeiger. 1936;15(7):97–106.

100. Komai T. Internal structure of the pterobranch Atubaria heterolopha with an appendix on the homology of the ‘notochord’. Proc. Japan Acad. 1949;25(7):19–24.

101. Halanych K. Convergence in the feeding appara­tuses of lophophorates and pterobranch hemichordates re­vealed by 18S rDNA: An interpretation. Biol. Bull. 1996;190(1):1–5. DOI: 10.2307/1542669

102. Щепотьев А. Pterobranchia. Санкт-Петербург: Типография Стасюлевича; 1907. 248 с.

103. Lester S.M. Cephalodiscus sp. (Hemichordata: Pterobranchia): observations of functional morphology, be­havior and occurrence in shallow water around Bermuda. Mar. Biol. 1985;85(3):263–268. DOI: 10.1007/BF00393246

104. Maletz J., Cameron C.B. Treatise on invertebrate paleontology, part V, chapter 3: introduction to class Ptero­branchia Lankester, 1877. Treatise Online. 2016;82:1–15.

105. Bather-London F.A. Vortrage und diskussionen auf der Wiener Tagung der Palaeontologischen Gesellschaft im September 1923: Cothurnocystis: a study in adaptation. Paläontologische Zeitschrift. 1926;7(1):1–15.

106. Jefferies R.P.S. Some fossil chordates with echino­derm affinities. Symp. Zool. Soc. Lond. 1967;20:163–208.

107. Jefferies R.P.S. The ancestry of the vertebrates. Bri-tish Museum (Natural History) & Cambridge University Press; 1986. 376 pp.

108. Ubaghs G. Stylophora. Treatise on Invertebrate Paleontology. Part S. Echinodermata, vol. 1. Ed. R.C. Moore. Lawrence: Geological Society of America and University of Kansas Press; 1968:495–565.

109. Ubaghs G. Early Paleozoic echinoderms. Ann. Rev. Earth Planet. Sci. 1975;3(1):79–98.

110. Ruta M. Brief review of the stylophoran debate. Evol. Dev. 1999;1(2):123–135. DOI: 10.1046/j.1525-142x.1999.99008.x

111. Kapli P., Natsidis P., Leite D.J., Fursman M., Jef­frie N., Rahman I.A., Philippe H., Copley R.R., Telford M.J. Lack of support for Deuterostomia prompts reinterpretation of the first Bilateria. Sci. Adv. 2021;7(12):eabe2741. DOI: 10.1126/sciadv.abe2741

112. Silva A.S., Natsidis P., Piovani L., Kapli P., Tel­ford M.J. Is the deuterostome clade an artifact? Curr. Biol. 2025;35(15):3611–3623. DOI: 10.1016/j.cub.2025.06.045

113. Cannon J.T., Vellutini B.C., Smith J. 3rd, Ron­quist F., Jondelius U., Hejnol A. Xenacoelomorpha is the sister group to Nephrozoa. Nature. 2016;530(7588):89–93. DOI: 10.1038/nature16520

114. Philippe H., Brinkmann H., Copley R.R., Moroz L.L., Nakano H., Poustka A.J., Wallberg A., Peterson K.J., Telford M.J. Acoelomorph flatworms are deuterostomes related to Xenoturbella. Nature. 2011;470(7333):255–258. DOI: 10.1038/nature09676

115. Philippe H., Poustka A.J. Chiodin M. et al. Miti­gating anticipated effects of systematic errors supports sis­ter-group relationship between Xenacoelomorpha and Am­bulacraria. Curr. Biol. 2019;29(11):1818–1826. DOI: 10.1016/j.cub.2019.04.009

116. Martynov A., Lundin K., Picton B., Fletcher K., Malmberg K., Korshunova T. Multiple paedomorphic line­ages of soft-substrate burrowing invertebrates: parallels in the origin of Xenocratena and Xenoturbella. PLoS One. 2020;15(1):e0227173. DOI: 10.1371/journal.pone.0227173

117. Международный кодекс зоологической номенкла­туры. Изд. 4-e. М.: Т-во науч. изд. КМК; 2004. 223 с.

118. Kuhn T.S. The Structure of Scientific Revolutions. University of Chicago Press; 1962. 172 pp.

119. Гинзбург В.Л. О физике и астрофизике: Ста­тьи и выступления. М.: Наука; 1992. 528 с.

120. de Beaumarchais P.-A.C. La Folle Journee, ou le Mariage de Figaro. Paris: De l’Imprimerie de la Societe Lit­teraire-Typographique; 1785. 201 pp.