| Species (N=922) | GC (%) | AT (%) | G (bases) | C (bases) | A (bases) | T (bases) | Maximum lifespan (yrs) |
|---|---|---|---|---|---|---|---|
| Manouria emys | 38.3 | 61.7 | 359 | 235 | 406 | 551 | 19.9 |
| Martes americana | 37.5 | 62.5 | 324 | 242 | 416 | 527 | 17.8 |
| Martes flavigula | 36.5 | 63.5 | 313 | 238 | 422 | 535 | 16.0 |
| Martes foina | 37.8 | 62.2 | 324 | 247 | 414 | 525 | 18.2 |
| Martes martes | 37.0 | 63.0 | 315 | 243 | 424 | 527 | 18.2 |
| Martes pennanti | 37.5 | 62.5 | 319 | 245 | 416 | 525 | 14.3 |
| Martes zibellina | 37.0 | 63.0 | 320 | 239 | 420 | 530 | 18.4 |
| Mauremys japonica | 38.2 | 61.8 | 356 | 238 | 411 | 549 | 16.2 |
| Mauremys mutica | 37.3 | 62.7 | 344 | 235 | 419 | 553 | 22.1 |
| Mazama americana | 35.8 | 64.2 | 305 | 238 | 432 | 540 | 17.1 |
| Mecistops cataphractus | 42.9 | 57.1 | 394 | 271 | 390 | 495 | 56.1 |
| Megalops atlanticus | 44.7 | 55.3 | 402 | 295 | 372 | 491 | 55.0 |
| Megalops cyprinoides | 44.9 | 55.1 | 405 | 296 | 369 | 490 | 44.0 |
| Megaptera novaeangliae | 36.9 | 63.1 | 332 | 230 | 422 | 537 | 95.0 |
| Melamprosops phaeosoma | 41.3 | 58.7 | 366 | 271 | 403 | 502 | 9.2 |
| Melanogrammus aeglefinus | 45.4 | 54.6 | 387 | 311 | 376 | 463 | 20.0 |
| Meleagris gallopavo | 42.1 | 57.9 | 378 | 269 | 390 | 501 | 13.0 |
| Meles meles | 36.3 | 63.7 | 309 | 237 | 428 | 531 | 18.6 |
| Melogale moschata | 37.2 | 62.8 | 319 | 244 | 426 | 526 | 19.0 |
| Melopsittacus undulatus | 41.8 | 58.2 | 392 | 251 | 377 | 519 | 21.0 |
| Melursus ursinus | 37.0 | 63.0 | 313 | 244 | 420 | 529 | 33.3 |
| Menidia menidia | 47.3 | 52.7 | 401 | 337 | 364 | 457 | 2.0 |
| Mephitis mephitis | 35.6 | 64.4 | 307 | 230 | 428 | 544 | 13.9 |
| Meriones unguiculatus | 36.2 | 63.8 | 302 | 237 | 420 | 532 | 6.3 |
| Merlangius merlangus | 45.7 | 54.3 | 387 | 314 | 372 | 462 | 20.0 |
| Merluccius merluccius | 47.2 | 52.8 | 407 | 318 | 369 | 441 | 20.0 |
| Mesocricetus auratus | 35.4 | 64.6 | 293 | 237 | 455 | 513 | 3.9 |
| Mesoplodon europaeus | 36.6 | 63.4 | 326 | 226 | 425 | 533 | 48.0 |
| Metachirus nudicaudatus | 32.6 | 67.4 | 279 | 202 | 467 | 528 | 3.0 |
| Microhyla ornata | 43.3 | 56.7 | 378 | 285 | 409 | 459 | 5.0 |
| Micromesistius poutassou | 45.9 | 54.1 | 384 | 321 | 376 | 455 | 20.0 |
| Micropterus dolomieu | 46.0 | 54.0 | 393 | 320 | 375 | 463 | 26.0 |
| Micropterus salmoides | 45.6 | 54.4 | 392 | 315 | 380 | 464 | 23.0 |
| Micrurus fulvius | 42.4 | 57.6 | 356 | 247 | 362 | 458 | 19.0 |
| Minytrema melanops | 44.9 | 55.1 | 393 | 313 | 386 | 480 | 6.0 |
| Mogera wogura | 36.1 | 63.9 | 314 | 233 | 442 | 526 | 3.2 |
| Monodelphis domestica | 34.0 | 66.0 | 280 | 207 | 447 | 499 | 5.1 |
| Monodon monoceros | 37.6 | 62.4 | 329 | 240 | 414 | 531 | 50.0 |
| Morone saxatilis | 43.6 | 56.4 | 386 | 318 | 414 | 495 | 30.0 |
| Mugil cephalus | 44.8 | 55.2 | 392 | 307 | 379 | 482 | 16.0 |