大部分鳥類都會飛，只有少數例外（比如鴕鳥）。飛鳥的體型受制於空氣動力學，再大也不能超過一個上限。有一種古代的飛鳥，體型巨大，接近極限。這種鳥應該就是有史以來最大的飛鳥了。
This may be the largest flying bird ever
by Riley Black
Imagine an albatross（信天翁） with a hacksaw（鋼鋸） for a mouth. Set that strange creature about 50 million years in the past and you've got the image of a pelagornithid（鋸齒鳥）, a group of ancient avians（鳥） that included some of the largest flying birds of all time.
imagine /ɪˈmædʒɪn/ v. 想像
image /ˈɪmɪdʒ/ n. 圖片、圖像
ancient /ˈeɪnʃ(ə)nt/ adj. 古老的
Now paleontologists（古生物學家） have uncovered in that group what may be the largest known flying birds ever, with wingspans of roughly six meters. By comparing a pair of polar fossils to the remains of related birds, paleontologists have been able to identify the early history of enormous fliers that were some of the first birds capable of soaring across seas.
uncover /ʌnˈkʌvə(r)/ v. 發現
wingspan /ˈwɪŋspæn/ n. 翼展
roughly /ˈrʌfli/ adv. 大約
polar /ˈpəʊlə(r)/ adj. 極地的
fossil /ˈfɒs(ə)l/ n. 化石
remains /rɪˈmeɪnz/ n. 遺骸、遺體
related /rɪˈleɪtɪd/ adj. 有親緣關係的
identify /aɪˈdentɪfaɪ/ v. 識別、發現
enormous /ɪˈnɔːməs/ adj. 巨大的
flier /ˈflaɪə(r)/ n. 飛行者（由fly加上表示人或物的後綴-er）
capable /ˈkeɪpəb(ə)l/ adj. 有能力的
soar /sɔː(r)/ v. 高飛、翱翔
During the 1980s, University of California Berkeley paleontologist Peter Kloess says, scientists searching for Antarctic fossils found some delicate bird bones – a jaw and part of a foot from an ancient bird. Those bones made a long journey to California, and Kloess and colleagues have researched them recently.
Antarctic /ænˈtɑːktɪk/ adj. 南極洲的、南極地區的
delicate /ˈdelɪkət/ adj. 易損壞的
jaw /dʒɔː/ n. 下頜、頜骨
California /ˌkælɪˈfɔːniə/ n. 加利福尼亞（美國西部的州）
research /rɪˈsɜːtʃ/ v. 研究
The bird jaw, which came from a rock formation laid down over 37 million years ago, looks almost like a woodcutting tool rather than a bone. The jaw has a series of large and small spikes, outgrowths of the beak that have a passing resemblance to teeth. Because of that feature, the paleontologists immediately identified the jaw as belonging to a pelagornithid, also known as bony-toothed birds that have a very long fossil record. The oldest pelagornithids evolved about 56 million years ago, and the most recent flew through the skies about two million years ago.
formation /fɔːˈmeɪʃ(ə)n/ n. 形成的事物（由form加後綴-ation變成名詞；rock formation指巖層）
woodcutting /ˈwʊdkʌtɪŋ/ n. 伐木
series /ˈsɪəriːz/ n. 一系列
spike /spaɪk/ n. 尖刺
outgrowth /ˈaʊtɡrəʊθ/ n. 長在（動植物）體外的東西
beak /biːk/ n. 鳥嘴、鳥喙
resemblance /rɪˈzembləns/ n. 相似（a passing resemblance意思是「有點相似」）
feature /ˈfiːtʃə(r)/ n. 特性、特徵
bony-toothed 骨牙的
record /ˈrekɔːd/ n. 記錄
evolve /ɪˈvɒlv/ v. 進化
The foot bone came from another large Antarctic pelagornithid, but its real importance was in its age. The fossil was found in a rock layer in the La Meseta Formation, about 50 million years old. This falls within a time called the Eocene（始新世）, when life had recovered from the asteroid-induced mass extinction and was thriving again. Together, the foot bone and the jaw indicate that large bony-toothed birds thrived in the Antarctic for millions of years.
recover /rɪˈkʌvə(r)/ v. 恢復
asteroid-induced 小行星引發的
mass /mæs/ adj. 大量的、大批的
extinction /ɪkˈstɪŋkʃ(ə)n/ n. 滅絕（由extinct加後綴-ion變成名詞）
thrive /θraɪv/ v. 繁榮
indicate /ˈɪndɪkeɪt/ v. 指出、表明
the Antarctic 南極地區（包括南極洲和周邊海域）
Paleontologists have found bony-toothed birds from places all over the world, from New Zealand to South Carolina. The newly-described Antarctic fossils, though, are the oldest known and hint that these birds quickly diversified into a range of sizes within six million years of their origin. Previous studies have calculated that the largest of the bony-toothed birds were near the limit of how big a bird could get and still fly, meaning these birds are the strongest contenders（競爭者） for the largest flying birds to ever soar.
South Carolina /ˌkærəˈlaɪnə/ 南卡羅來納（美國東南部的州）
newly /ˈnjuːli/ adv. 新近、最近
hint /hɪnt/ v. 暗示
diversify /daɪˈvɜːsɪfaɪ/ v. 多元化、多樣化（由diverse加後綴-ify變成動詞）
origin /ˈɒrɪdʒɪn/ n. 起源
calculate /ˈkælkjuleɪt/ v. 計算
Matched with the new data on the age of the fossils, Kloess says, "we can say that giant pelagornithids appeared earlier than previously known and that Antarctica saw a range of pelagornithid sizes from the early to late Eocene." Small to large, bony-toothed birds were an important part of ancient Antarctic ecosystems.
data /ˈdeɪtə/ n. 數據
giant /ˈdʒaɪ(ə)nt/ adj. 巨大的、巨型的
Antarctica /ænˈtɑːktɪkə/ n. 南極洲
ecosystem /ˈiːkəʊˌsɪstəm/ n. 生態系統（由system加上表示生態的前綴eco-）
英文原文節選自Smithsonian Magazine
https://www.smithsonianmag.com/science-nature/scientists-reveal-what-may-be-largest-flying-bird-ever-180976128/