Alignment of anterior somites (body segments) and appendages across various <a href="https://en.wikipedia.org/wiki/euarthropod" class="extiw" title="en:euarthropod">euarthropod</a> taxa. Extinct taxa based on the most widely-accepted interpretations of mid 2010s.
<ul><li>†: Extinct taxa</li>
<li>0: Ocular somite</li>
<li>1-2: Somite 1-10 (further somite(s) ommited)</li>
<li>Dark grey: Somite(s) of head tagma (head/cephalon/prosoma)</li>
<li>Red/P: Protocerebral somite/appendage</li>
<li>Yellow/D: Deutocerebral somite/appendage</li>
<li>Blue/T: Tritocerebral somite/appendage</li></ul><p>†<b><a href="https://en.wikipedia.org/wiki/Fuxianhuiida" class="extiw" title="en:Fuxianhuiida">Fuxianhuiida</a></b> (fuxianhuiid):
</p>
<ul><li>Hy/Lbr: <a href="https://en.wikipedia.org/wiki/Hypostome" class="extiw" title="en:Hypostome">Hypostome</a>/<a href="https://en.wikipedia.org/wiki/Labrum_(arthropod_mouthpart)" class="extiw" title="en:Labrum (arthropod mouthpart)">labrum</a> complex</li>
<li>An: Antenna</li>
<li>SPA: Specialized post-antennal appendage</li>
<li>L: (<a href="https://en.wikipedia.org/wiki/Arthropod_leg" class="extiw" title="en:Arthropod leg">Arthropodized</a>) Leg/walking leg</li></ul><p>†<b><a href="https://en.wikipedia.org/wiki/Megacheira" class="extiw" title="en:Megacheira">Megacheira</a></b> (megacheiran/great appendage arthropod):
</p>
<ul><li>Hy/Lbr: Hypostome/labrum complex</li>
<li>SGA: Short-<a href="https://en.wikipedia.org/wiki/great_appendage" class="extiw" title="en:great appendage">great appendage</a></li>
<li>L: (Arthropodized) Leg/walking leg</li></ul><p>†<b><a href="https://en.wikipedia.org/wiki/Artiopoda" class="extiw" title="en:Artiopoda">Artiopoda</a></b> (artiopodan/artiopod: <a href="https://en.wikipedia.org/wiki/trilobite" class="extiw" title="en:trilobite">trilobite</a>, <a href="https://en.wikipedia.org/wiki/aglaspidid" class="extiw" title="en:aglaspidid">aglaspidid</a> etc.):
</p>
<ul><li>Hy/Lbr: Hypostome/labrum complex</li>
<li>An: Antenna</li>
<li>L: (Arthropodized) Leg/walking leg</li></ul><p><b><a href="https://en.wikipedia.org/wiki/Chelicerata" class="extiw" title="en:Chelicerata">Chelicerata</a>: <a href="https://en.wikipedia.org/wiki/Pycnogonida" class="extiw" title="en:Pycnogonida">Pycnogonida</a></b> (pycnogonid/sea spider):
</p>
<ul><li>?: (Appendage unknown)</li>
<li>Chf: Chelifore</li>
<li>P: Palp</li>
<li>Ovg: Oviger</li>
<li>L: (Arthropodized) Leg/walking leg</li></ul><p><b>Chelicerata: Euhelicerata</b> (euchelicerate: "merostome" and <a href="https://en.wikipedia.org/wiki/arachnid" class="extiw" title="en:arachnid">arachnid</a>): 
</p>
<ul><li>Hy/Lbr: Hypostome/labrum complex</li>
<li>Chr: <a href="https://en.wikipedia.org/wiki/Chelicera" class="extiw" title="en:Chelicera">Chelicera</a></li>
<li>Pp: <a href="https://en.wikipedia.org/wiki/Pedipalp" class="extiw" title="en:Pedipalp">Pedipalp</a></li>
<li>L: (Arthropodized) Leg/walking leg</li></ul><p><b><a href="https://en.wikipedia.org/wiki/Myriapoda" class="extiw" title="en:Myriapoda">Myriapoda</a></b> (myriapod: <a href="https://en.wikipedia.org/wiki/centipede" class="extiw" title="en:centipede">centipede</a>, <a href="https://en.wikipedia.org/wiki/millipede" class="extiw" title="en:millipede">millipede</a> etc.):
</p>
<ul><li>Hy/Lbr: Hypostome/labrum complex</li>
<li>An: Antenna</li>
<li>Inc: intercalary segment</li>
<li>Mnd: <a href="https://en.wikipedia.org/wiki/Mandible_(arthropod_mouthpart)" class="extiw" title="en:Mandible (arthropod mouthpart)">Mandible</a></li>
<li>Mx1: First <a href="https://en.wikipedia.org/wiki/Maxilla_(arthropod_mouthpart)" class="extiw" title="en:Maxilla (arthropod mouthpart)">maxilla</a></li>
<li>Mx2: Second maxilla</li>
<li>L: (Arthropodized) Leg/walking leg</li></ul><p><b>"<a href="https://en.wikipedia.org/wiki/Crustacea" class="extiw" title="en:Crustacea">Crustacea</a>"</b> (crustacean: <a href="https://en.wikipedia.org/wiki/Decapoda" class="extiw" title="en:Decapoda">shrimp, crab</a>, <a href="https://en.wikipedia.org/wiki/barnacle" class="extiw" title="en:barnacle">barnacle</a>, <a href="https://en.wikipedia.org/wiki/waterflea" class="extiw" title="en:waterflea">waterflea</a> etc.):
</p>
<ul><li>Hy/Lbr: Hypostome/labrum complex</li>
<li>An1: First <a href="https://en.wikipedia.org/wiki/Antenna_(biology)#Crustaceans" class="extiw" title="en:Antenna (biology)">antenna</a>/antennula/antennule</li>
<li>An2: Second antenna/antenna</li>
<li>Mnd: Mandible</li>
<li>Mx1: First maxilla/maxillula</li>
<li>Mx2: Second maxilla/maxilla</li>
<li>L: (Arthropodized) Leg/walking leg</li></ul><p><b><a href="https://en.wikipedia.org/wiki/Hexapoda" class="extiw" title="en:Hexapoda">Hexapoda</a></b> (hexapod: <a href="https://en.wikipedia.org/wiki/insect" class="extiw" title="en:insect">insect</a>, <a href="https://en.wikipedia.org/wiki/springtail" class="extiw" title="en:springtail">springtail</a> etc.)
</p>
<ul><li>Hy/Lbr: Hypostome/labrum complex</li>
<li>An: <a href="https://en.wikipedia.org/wiki/Insect_morphology#Antennae" class="extiw" title="en:Insect morphology">Antenna</a></li>
<li>Inc: intercalary segment</li>
<li>Mnd: Mandible</li>
<li>Mx: <a href="https://en.wikipedia.org/wiki/Insect_mouthparts#Maxilla" class="extiw" title="en:Insect mouthparts">Maxilla</a></li>
<li>Lbi: <a href="https://en.wikipedia.org/wiki/Insect_mouthparts#Labium" class="extiw" title="en:Insect mouthparts">Labium</a></li>
<li>L: (Arthropodized) Leg/walking leg</li></ul><p><a href="https://en.wikipedia.org/wiki/Panarthropoda" class="extiw" title="en:Panarthropoda">Panarthropod</a> version:<br><a href="//commons.wikimedia.org/wiki/File:20191106_Panarthropoda_head_segments_appendages_en.png" class="image"><img alt="20191106 Panarthropoda head segments appendages en.png" src="https://upload.wikimedia.org/wikipedia/commons/thumb/2/2e/20191106_Panarthropoda_head_segments_appendages_en.png/300px-20191106_Panarthropoda_head_segments_appendages_en.png" decoding="async" width="300" height="61" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/2/2e/20191106_Panarthropoda_head_segments_appendages_en.png/450px-20191106_Panarthropoda_head_segments_appendages_en.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/2/2e/20191106_Panarthropoda_head_segments_appendages_en.png/600px-20191106_Panarthropoda_head_segments_appendages_en.png 2x" data-file-width="2600" data-file-height="530"></a>
</p><p>Extant panarthropod version:<br><a href="//commons.wikimedia.org/wiki/File:20191107_Panarthropoda_head_segments_appendages_extant_en.png" class="image"><img alt="20191107 Panarthropoda head segments appendages extant en.png" src="https://upload.wikimedia.org/wikipedia/commons/thumb/a/a4/20191107_Panarthropoda_head_segments_appendages_extant_en.png/300px-20191107_Panarthropoda_head_segments_appendages_extant_en.png" decoding="async" width="300" height="103" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/a/a4/20191107_Panarthropoda_head_segments_appendages_extant_en.png/450px-20191107_Panarthropoda_head_segments_appendages_extant_en.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/a/a4/20191107_Panarthropoda_head_segments_appendages_extant_en.png/600px-20191107_Panarthropoda_head_segments_appendages_extant_en.png 2x" data-file-width="1550" data-file-height="530"></a>
</p><p>References：
</p>
<ul><li>Ortega-Hernández, Javier; Janssen, Ralf; Budd, Graham E. (2017-05). <a rel="nofollow" class="external text" href="https://www.sciencedirect.com/science/article/abs/pii/S1467803916301669">Origin and evolution of the panarthropod head – A palaeobiological and developmental perspective</a>. Arthropod Structure &amp; Development 46 (3): 354–379. doi:10.1016/j.asd.2016.10.011</li></ul><dl><dd>Overall review.</dd></dl><ul><li>Dunlop, Jason A.; Lamsdell, James C. (2017-05). <a rel="nofollow" class="external text" href="https://www.academia.edu/28212892">Segmentation and tagmosis in Chelicerata</a>. Arthropod Structure &amp; Development 46 (3): 395–418. doi:10.1016/j.asd.2016.05.002</li></ul><dl><dd>Chelicerata, Megacheira.</dd></dl><div class="description mw-content-ltr ja" dir="ltr" lang="ja"><span class="language ja" title="Japanese"><b>日本語:</b></span> <a href="//commons.wikimedia.org/wiki/File:20190913_Arthropoda_head_segments_appendages_ja.png" class="image"><img alt="20190913 Arthropoda head segments appendages ja.png" src="https://upload.wikimedia.org/wikipedia/commons/thumb/b/b6/20190913_Arthropoda_head_segments_appendages_ja.png/300px-20190913_Arthropoda_head_segments_appendages_ja.png" decoding="async" width="300" height="91" srcset="https://upload.wikimedia.org/wikipedia/commons/thumb/b/b6/20190913_Arthropoda_head_segments_appendages_ja.png/450px-20190913_Arthropoda_head_segments_appendages_ja.png 1.5x, https://upload.wikimedia.org/wikipedia/commons/thumb/b/b6/20190913_Arthropoda_head_segments_appendages_ja.png/600px-20190913_Arthropoda_head_segments_appendages_ja.png 2x" data-file-width="1750" data-file-height="530"></a></div>
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