About this opening
Pterodactyl Defense: Sicilian, Pteranodon is an opening in the Encyclopedia of Chess Openings,
classified under code B27. ECO group B (B00–B99)
covers semi-open games (1.e4 with Black playing anything other than 1…e5), with the Sicilian, French, Caro-Kann and Pirc/Modern at its heart. This particular variation is reached
after 11 half-moves from the
starting position, with the move sequence 1. e4 c5 2. Nf3 g6 3. d4 Bg7 4. dxc5 Qa5+ 5. Nc3 Bxc3+ 6. bxc3.
It belongs to the Pterodactyl Defense family. Within that family this is a level-2 branch (the Sicilian → Pteranodon line).
The opening sequence in prose form: 1.e4 c5, 2.Nf3 g6, 3.d4 Bg7, 4.dxc5 Qa5+, 5.Nc3 Bxc3+, 6.bxc3. From this position the encyclopaedia records no further canonical continuations — practical play branches into unnamed transpositions or returns to the parent line for alternative ideas.
Use the interactive board above to walk through the moves position-by-position. Click any move in the navigation to step backwards, or use the keyboard arrow keys. For statistical data — how often master-level players have reached this position, White's win-rate, draw frequency, Black's score — see the panel in the right column.
Caissly's coverage of B27 extends through every named sub-variation in this line and across all four locales (English, Spanish, Portuguese, Russian). Where editorial commentary exists for a specific variation it appears as the page body; otherwise the page presents the structural data, board, and statistics as shown here.